3rd ECFA workshop on e+e- Higgs/EW/Top Factories, Paris, 9-11 Oct. 24

9 Oct 2024, 08:00 → 11 Oct 2024, 16:50 Europe/Paris

Amphi Farabeuf (Campus des Cordeliers, Paris, Metro Odeon)

Giovanni Marchiori (APC Paris), Gregorio Bernardi (APC Paris CNRS/IN2P3), Nicolas Morange (IJCLab)

Dear Colleagues,

The third ECFA workshop on e⁺e^- Higgs, Electroweak and Top Factories will take place in the center of Paris in an in-person mode.

The Workshop will last from Wednesday, October 9th, 2024, 09:00 to Friday, October 11th, 16:00.

Registration is now CLOSED. It is not possible to register anymore, not even on site.

This workshop will be the last of the series of workshops on the physics, experiment and detectors for future e+e- factories before the start of the process of the next update of the European Strategy on Particle Physics. It thus provides a crucial opportunity for the community working on the future e+e- factories to get together and discuss the latest results and developments in view of the submission of a report as input to the next strategy update.

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The central entry point of the ECFA study is accessible through this link

Previous editions:

• First ECFA workshop, Hamburg, 2022
• Second ECFA workshop, Paestum, 2023

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Poster ECFA-WS-Higgs-EW-topFactories-V6-4K.jpg ECFA-WS-Higgs-EW-topFactories-V6-4K.pdf

Wednesday 9 October

08:30 → 09:00 Registration

09:00 → 10:30 Plenary

Conveners: Aidan Robson (University of Glasgow), Aidan Robson (University of Glasgow)

09:00 News from the local organizers

Speakers: G. Bernardi (APC Paris CNRS/IN2P3), G. Marchiori (APC Paris), N. Morange (IJCLab)

Welcome.pdf

09:10 Welcome from IN2P3 and IRFU

Speaker: Dr Christelle Roy (CNRS / IN2P3)

09:30 ESPPU process and timeline; goals of the workshop

Speaker: Paris Sphicas (Athens/CERN)

2024-10-09-HET-Wkshp-Intro.pdf

09:45 The need for a Higgs, Electroweak, and Top factory

Speaker: Margarete Mühlleitner (ITP, KIT)

ECFAOct2024.pdf

10:15 Software for future colliders

Speaker: Juraj Smiesko (CERN)

Software for future colliders

Software for future colliders.pdf

10:30 → 11:00 coffee break

11:00 → 13:00 Parallel - WG1-HTE: Hss and ZH

Conveners: Chris Hays (Oxford University), Fabio Maltoni (UCLouvain/Unibo), Karsten Köneke (University of Freiburg)

11:00 Measurement of hadronic Higgs boson decays at FCC-ee to constrain quarks and gluon couplings

We report on the latest sensitivity studies of FCC-ee to the measurement of the branching ratios of Higgs boson decays to quark-antiquark pairs and gluons.
The studies use simulated events scaled to integrated luminosities of 10.8/ab of sqrt(s)=240 GeV and 3.0/ab of sqrt(s)=365 GeV.
Jet flavour tagging is exploited to distinguish among different Higgs boson decays.
Various final states (H(jj) + ee/mumu, H(jj) + jj and H(jj) + missing energy) are reconstructed and a joint interpretation of their results is performed.
The expected precision in the branching ratios of decays to b,c,g is at the %-level or better, while that for the H->ss decay is close to the predicted branching ratio in the Standard Model.

Speaker: Alexis Maloizel (APC, Paris)

ECFA_MALOIZEL_HiggsCouplingsZHFCC_fin.pdf

11:20 Strange tagging with ILD full simulation and application to H->ss analysis

Higgs to ss analysis is one of the ECFA HTE focused topics. We are working on the H->ss analysis using ILD full simulation based on a previous ILD study on H->bb/cc/gg branching ratio measurement and a latest DNN-based jet flavor tagging tool. This talk will focus on the application of strange tagging to the H->ss analysis including performance studies of strange tagging as well as results on H->ss sensitivity on ILD. Dependence on PID performance or detector configuration can be discussed as well.
(Details of analysis may be shown on a separate poster to be submitted by our student.)

Speaker: Dr Taikan Suehara (ICEPP, The University of Tokyo)

241009-stag-ecfaws-suehara.pdf

11:40 Detector impact on flavour tagging at the FCC-ee

The ParticleNet tagger is a graph neural network devoted to the tagging of jets from the hadronization of multiple flavors at the FCC-ee. Its impressive and unprecedented tagging performance allows for accessing rare and challenging hadronic final states. This study shows the fast-simulation-based characterization of the ParticleNet performance evolution as a function of the IDEA vertex detector single-hit resolution, material radiation length and number of layers. Furthermore, an attempt to study impacts in physics applications such as the all-hadronic and Higgs-invisible ZH final states will be shown.

Speaker: Andrea Sciandra (BNL)

Sciandra_ECFA2024_10_09_24.pdf

12:00 Impact of changes in the flavour tagger performance on the Higgs coupling measurements in ZH fully hadronic final states at the FCCee

The FCC-ee is a potential future Higgs factory that can continue to probe the validity of the electroweak theory. One of the key tasks is to study how the next generation of particle detectors can be optimised to study the Higgs boson in detail. This study uses the ZH process, where both the Higgs and Z decay to a pair of jets, to investigate the impact of changing the flavour tagger performance on the measurements of the Higgs coupling with the IDEA detector concept proposed for FCC-ee. The ParticleNet Tagger currently in use as a baseline in FCC-ee studies is re-trained for various possible IDEA vertex detector configurations. The ZH fully hadronic analysis is rerun for each re-trained tagger, and the expected 68% Confidence Level uncertainty on the Higgs coupling to the b-, c-, s-quarks and the gluon is used as the metric to determine the impact of the flavour tagger’s performance.

Speaker: Iza Veliscek (Brookhaven National Laboratory)

ZH All Had [FCC - 11 Oct]-4.pdf

12:20 CP-violation in complex-singlet extension of 2HDM

We explore the possibility of CP-violation in the complex-singlet extension of 2HDM. The addition of complex singlet paves the way for additional sources of CP-violation compared to 2HDM. If a Z2-symmetry is imposed on the complex-singlet, it can accommodate a dark matter candidate as well. We identify the regions of parameter space, that can fit DM observables and at the same time generate sufficient CP-violation. The amount of CP-violation gets severely constrained from electric-dipole moment experiments, which we take into account. Finally, we probe the CP-violation in this model at present and future collider experiments.

Speaker: JAYITA LAHIRI (II. Theoretical Institute for Physics, University of Hamburg)

talk_CPV.pdf

12:40 Determination of CP-violating Higgs couplings with transversely-polarized beams at the ILC

We study possible CP-violation effects of the Higgs to Z-boson coupling
at a future e^+ e^- collider, e.g. the International Linear Collider (ILC). We find that the azimuthal angular distribution of the muon pair, produced by e+ e- -> H Z -> H mu+ mu-, can be sensitive to such a CP-violation effect when we apply initial transversely polarized beams. Based on this angular distribution, we construct a CP sensitive asymmetry and obtain this asymmetry by Whizard simulation. By comparing the SM prediction with 2 range of this asymmetry, we estimate the limit of the CP-odd coupling in HZZ interaction, including as well studies from unpolarized and longitudinally-polarized beams.

Speaker: Gudrid Moortgat-Pick (DESY and University of Hamburg)

Higgs-transv.pdf

11:00 → 13:00 Parallel - WG1-PREC

Conveners: Adrian Irles (IFIC (CSIC/UV) Valencia), Andreas Meyer (DESY), Andreas Meyer (DESY), Ayres Freitas (University of Pittsburgh), Fabio Maltoni Maltoni (UCL), JORGE DE BLAS (University of Granada), Jenny List (DESY), Paolo Azzurri (INFN Pisa), Paolo Azzurri, Patrick Koppenburg (Nikhef)

11:00 Reimagining Electron-Positron Collider Luminosity Measurements

Our recent work has shown that a novel, much higher granularity
forward calorimetry concept can enable much more detailed and precise
reconstruction than the baseline designs based on LEP luminometers, together
with the capability of electron/positron/photon separation.

This new calorimeter concept is designed primarily to maximize the acceptance
for $e^+e^- \to \gamma \gamma$ as an alternative luminosity process, where it serves
to define the inner edge of the acceptance (there is no outer edge - as the
complete detector is used in the measurement), while continuing to provide
the standard luminosity measurement from small angle Bhabhas. It will also
serve as a general forward electromagnetic calorimeter helping ensure hermeticity
and detecting individual electrons/positrons/photons.

In this contribution we will highlight the Bhabha rejection capability in the
context of the $e^{+}e^{-} \to \gamma \gamma$ luminosity measurement and investigate the
utility of a Bhabha ``mini-tracker'' consisting of a few planes of
upstream thin silicon detectors. This will further refine the $e^{+}$/$e^{-}$ polar angle measurement, improve Bhabha rejection (for gamma gamma), and,
last-but-not-least, help mitigate the beam-induced electromagnetic deflection
that biases the Bhabha acceptance by providing high precision longitudinal
vertex information in Bhabha events than can be used in diagnosing this
beam/final-state $e^{+}/e^{-}$ effect.

Speaker: Graham Wilson (University of Kansas)

ECFAParis-Lumi_V3.pdf

11:25 Precision studies of quantum electrodynamics at future e+e- colliders

We classify the possible deviations from the Standard Model in the QED-dominated $\mathrm{e^+e^-}\to\gamma\gamma$ process under the assumption of a preserved $SU(2)_L \times U(1)_Y$ symmetry. We find that the only deviations really observable in practice correspond to a correction of the differential cross section by a factor $(1 + \frac{c_8~s^2}{8\pi\alpha\Lambda^4}~\sin^2\theta)$, where $\Lambda$ is the scale of new physics, $\theta$ is the polar angle of any of the final state photons and $c_8$ is a constant of order 1.
We also provide sensitivity estimates for QED deviations at future $\mathrm{e^+e^-}$ facilities. An $\mathrm{e^+e^-}$ collider operating at $\sqrt{s}=3$ TeV could provide sensitivity to $\Lambda$ scales as large as 15 TeV, provided that acceptances and efficiencies are controlled at the per mille level. Finally, we also discuss the possibility of a measurement of the luminosity at the FCC-ee with $\lesssim 10^{-4}$ precision, using analyses of the $\mathrm{e^+e^-}\to\gamma\gamma$ process at $\sqrt{s}\approx m_Z$ energies.

Speaker: Juan Alcaraz Maestre (CIEMAT (Madrid))

Alcaraz_QED_9Oct2024(2).pdf

11:50 Probing New Physics at future e+e- colliders with two-particle angular correlations

Long-range angular correlations between particles could reveal physics beyond the Standard Model, such as Hidden Valley (HV) scenarios. Our emphasis is on a hidden QCD-like sector, where the emergence of HV matter alongside QCD partonic cascades could amplify and extend azimuthal correlations among final-state particles.

Our study at the detector level focuses on the detectability of these signals at future lepton colliders, offering a cleaner experimental environment compared to the Large Hadron Collider (LHC). Notably, the identification of ridge structures in the two-particle correlation function may hint the presence of new physics.

Speaker: Redamy Perez-Ramos

HV_Angular_Correlations.pdf

11:00 → 13:00 Parallel - WG1-SRCH

Conveners: Adrian Irles (IFIC (CSIC/UV) Valencia), Prof. Aleksander Filip Zarnecki (University of Warsaw), Andreas Meyer (DESY), Fabio Maltoni Maltoni (UCL), Jenny List (DESY), Paolo Azzurri (INFN Pisa), Paolo Azzurri, Patrick Koppenburg (Nikhef), Rebeca Gonzalez Suarez (Uppsala University (SE)), Roberto Franceschini (Roma Tre University and INFN Rome)

11:00 Overview on low mass scalars at e+e- facilities - theory

Speaker: Tania Robens

talk.pdf

11:20 Search for additional Higgs bosons at the FCC-ee

Speaker: Anne-Marie Magnan (Imperial College London)

iDMatFCC_ECFA24.pdf

11:40 Search for invisible decays of light scalars at Future Lepton Collider

Speaker: Aman Desai (University of Adelaide)

ECFA_Talk.pdf

12:00 Evidence for BSM physics in the scalar sector

Speaker: Francois Richard (LAL/Orsay)

ECFA-PARIS.pptx

ECFA-PARIS-TALK.pdf

12:20 Prospects for light exotic scalar measurements at the e+e- Higgs factory

Speaker: Prof. Aleksander Filip Zarnecki (University of Warsaw)

zarnecki_exscalar_ecfa2024_v1.pdf

12:40 Decay-mode independent searches for new light scalars at future Higgs factories

Speaker: María Teresa Núñez Pardo de Vera (DESY)

ExoticScalars_ECFAWS24.pdf

11:00 → 13:00 Parallel - WG3

Conveners: Felix Sefkow (Deutsches Elektronen-Synchrotron), Giovanni Marchiori (APC Paris), Dr Mary-Cruz Fouz (CIEMAT)

11:00 Design, performance and future prospects of vertex detectors at the FCC-ee

The CERN proposed $e^+e^-$ Future Circular Collider (FCC-ee) is designed as an electroweak, flavour, Higgs and top factory with unprecedented luminosities. Many measurements at the FCC-ee will rely on the precise determination of the vertices, measured by dedicated vertex detectors.

All vertex detector designs use Monolithic Active Pixel Sensors (MAPS) with a single-hit resolution of ≈3 µm and a material budget as low as 0.25% $X/X0$ per detection layer, which is within specifications for most of the physics analyses.

This contribution presents the status of the R&D on fully engineered vertex detector, together with the challenges due to its cooling and integration with the collider beam pipe. Discussions on an ultra-light vertex detector layout using curved wafer-scale MAPS are also presented, which allows reducing the material budget by about a factor of four, at the expenses of some losses in efficiency.

Speakers: Armin Ilg (University of Zürich), Fabrizio Palla (INFN Pisa)

Paris 3rd ECFA Vertex.pptx

11:24 CMOS R&D targeting a vertex detector for Higgs factories

The vertex detector of the future Higgs Factory requires particularly high demanding performances, in terms of granularity, material budget, Power Consumption, data acquisition bandwidth and time resolution. IPHC Strasbourg has been pursuing its R&D effort on CMOS pixel sensors through several axis. One proposes to present of synthesis of these activities:

1/ A large scale CMOS sensor, called MIMOSIS, is currently developed at IPHC-Strasbourg in a 180 nm technology to equip the Micro-Vertex Detector (MVD) of the CBM experiment at FAIR/GSI. Targeting to reach 5 um spatial resolution, 5 us time resolution, a peak rate of 80 MHz/cm2, a radiation doses of 5 MRad and up to 10^14 neq/cm^2 per year, MIMOSIS also plays the role of a demonstrator for Higgs factories. The last version (MIMOSIS-2.1) before the final production sensor has been produced in 2024 and is currently under test. Preliminary results will be presented. In particular, sensors produced with 50 microns epitaxial layer thickness will be compared to the regular process.
2/ IPHC is also pursuing its R&D effort on the TPSCo 65 nm technology, thanks to its CE_65 prototypes, through a detailed program studying the charge collection the charge encoding to optimize the spatial resolution for different pixel types. The next steps will consist in the exploration of new read-out architectures.

3/ To conclude, one will present our roadmap to propose a realistic, robust and large acceptance vertex detector in the context of FCCee, incorporating the R&D planned inside the DRD3.

Speaker: auguste besson (Institut Pluridisciplinaire Hubert Curien)

ECFA_Paris_2024__VTX_Besson.pdf

ECFA_Paris_2024__VTX_Besson.pptx

11:48 Large area low-power Monolithic CMOS Tracking Detectors for FCC-ee

High voltage CMOS pixel sensors are proposed to be used in future particle physics experiment such as FCC-ee. The ATLASPIX3 chip consists of 49000 pixels of dimension 50μm x 150 μm, realised in in TSI 180nm HVCMOS technology. It was the first full reticle size monolithic HVCMOS sensor suitable for construction of multi-chip modules and supporting serial powering through shunt-LDO regulators. The readout architecture supports both triggered and triggerless readout with zero-suppression.

With the ability to be operated in a multi-chip setting, a 4-layer telescope made of ATLASPix 3.1 was developed, using the GECCO readout system as for the single chip setup. To demonstrate the multi-chip capability and for its characterisation, a beam test was conducted at DESY using 3--6 GeV positron beams with the chips operated in triggerless readout mode with zero-suppression. The detector performance have also been tested with hadron beams and operating both with and without the built-in power regulators. Multichip modules have been operated and behaviour in a serial powering configuration has been tested.

Speaker: Yanyan Gao (University of Edinburgh)

large_area_tracker_ECFA_Oct24.pdf

12:12 Development of precision tracking detectors at Fermilab

Availability of low-power, highly granular detectors that will provide excellent position resolution is one of the key requirements for FCC-ee physics goals, and has been highlighted as a priority research directions for European Strategy and the P5 panels. Several technologies are currently being pursued in the HEP and NP communities to achieve these goals. We will present the latest developments on precision tracking detectors for FCC-ee applications at Fermilab. Efforts have been focused on advances towards manufacturing of novel sensors and on the design of sophisticated Application Specific Integrated Circuits (ASICs) required to achieve the ambitious goals of FCC-ee. We will present developments over several directions that aim to advance particle detectors technologies. The talk will cover our developments and plans for Monolithic Active Pixel Sensors for tracking and calorimeters, 3D-integrated sensors and dedicated ASICs, and 4D-tracking sensors. These projects are a result of successful collaborations among many US and international partners, and this collaborative aspects will be also presented.

Speaker: Artur Apresyan (Fermilab)

Tracking developments at Fermilab.pdf

12:36 The H2M project: Porting the functionality of a hybrid readout chip into a monolithic 65 nm CMOS imaging process

Monolithic active pixel sensors (MAPS) are attractive candidates for the next generation of vertex and tracking detectors for future lepton colliders. Especially an only recently accessible 65 nm CMOS imaging technology, that allows for higher logic density at lower power consumption compared to previously used imaging processes, is of high interest. To investigate this technology, explore the design challenges of porting a hybrid pixel detector architecture into a monolithic chip, and to exercise the digital-on-top design methodology, the H2M (Hybrid-to-Monolithic) test chip has been developed and manufactured. It features a 64x16 pixel matrix with a pitch of 35 × 35 µm², resulting in a total active area of approximately 1.25 mm². The sensitive pixel matrix is designed in the so called n-gap layout to optimise charge collection and boost the detection efficiency. This contribution introduces the H2M chip and presents results from calibration and test-beam measurement campaigns.

Speaker: Dominik Dannheim (CERN)

H2M-3rd-ECFA-Higgs-WS-9Oct2024.pdf

13:00 → 14:15 lunch break

14:15 → 16:15 Parallel - WG1-GLOB

Conveners: Fabio Maltoni Maltoni (UCL), JORGE DE BLAS (University of Granada), Jenny List (DESY), Patrick Koppenburg (Nikhef)

14:15 First WWdiff results from full simulation studies of WW and single-W production

Differential measurements of WW production have a long history in the (linear) $e^{+}e^{-}$-collider community. In particular, to determine the (anomalous) triple gauge couplings (aTGC) and the longitudinal beam polarization. However, if done in full simulation at all, these studies focused on higher center-of-mass energies of 500-1000 GeV. So far only extrapolations of these results to the "typical" Higgs factory energies of 240-250 GeV were given. Additionally, the focus was mostly on "pure" WW production, while the importance of single-W production has become more apparent only recently.
In this talk, we present the first results of a full-simulation study at 240-250 GeV, with a focus on the $e\nu q\bar{q}$ final state, including single-W production. We perform the study in a detector-agnostic way and compare results for the CLD@FCC-ee and ILD@ILC detector models using the Key4hep software stack.

Speaker: Leonhard Reichenbach (CERN / University of Bonn)

241009_ECFA_reichenbach.pdf

14:35 The top quark EW couplings in the SMEFT

In this contribution by the IFIT/C group we present a global SMEFT analysis of the top sector. We indclude measurements by ATLAS and CMS using the LHC run 2 data, as well as projections for the HL-LHC and the future electron-positron collider projects. We update the fits for the Snowmass study (arXiv:2206.08326) with new LHC results, new projections for ttll four-fermion operators and a new scenario for the muon collider.

This study is part of the focus topic "ttbar threshoold" of the ECFA Higgs/top7ew factory studies.

Speaker: Marcel vos (IFIC - centro mixto U. Valencia/CSIC, Valencia, Spain)

TopCouplingsFutureCollider.pdf

14:55 Precise measurements of top CKM and EWK couplings at FCC-ee

The electron-positron phase of the Future Circular Collider (FCC-ee) at CERN is proposed as a Higgs, electroweak, flavour, and top factory at the intensity frontier. In particular, about 2 million top quark pairs are expected to be produced at the 365 GeV operation, providing a clean dataset with unprecedented opportunities for top property measurements. This talk covers recent studies on two measurements, along with relevant technical developments and phenomenological discussions: one is a direct determination of the CKM matrix element |Vts| through the top quark to W and s quark decay, and the other is a thorough probe of potential BSM modifications to ttgamma and ttZ couplings via the angular distributions of top decay products.

Speaker: Xunwu Zuo (Karlsruhe Institute of Technology)

top quark CKM and EWK couplings 2024.10.09.pdf

15:15 Mapping the SMEFT at High-Energy Colliders: from LEP and the (HL-)LHC to the FCC-ee

We present SMEFiT3.0, an updated global SMEFT analysis of Higgs, top quark, and diboson data from the LHC complemented by electroweak precision observables (EWPOs) from LEP and SLD. We estimate the impact on the SMEFT parameter space of HL-LHC measurements when added on top of SMEFiT3.0 by means of dedicated projections that extrapolate Run II data. Subsequently, we quantify the unprecedented impact that measurements from future electron-positron colliders would have on both the SMEFT parameter space and on UV-complete models. We present projections for the FCC-ee and the CEPC based on the most recent running scenarios and include Z-pole EWPOs, fermion-pair, Higgs, diboson, and top quark production, using optimal observables for both $W^+W^-$ and $t\bar{t}$. Finally, we quantify the effect of renormalization group running on the sensitivity to the SMEFT parameter space and UV-complete models.

Speaker: Jaco ter Hoeve (Nikhef)

ecfa_paris_24_JtH.pdf

15:35 Determination of large systems of SMEFT operator coefficients with Higgs factory data

Speaker: Michael Peskin (SLAC)

SMEFT for Higgs at ECFA 2024.pdf

14:15 → 16:15 Parallel - WG1-HTE: Joint HTE+SRCH session

Conveners: Chris Hays (Oxford University), Fabio Maltoni Maltoni (UCL), Karsten Köneke (University of Freiburg), Rebeca Gonzalez Suarez (Uppsala University (SE))

14:15 Searching for heavy neutral leptons through exotic Higgs decays at the ILC

Speaker: Junping Tian (University of Tokyo)

HNL_ECFA_Thor.pdf

14:35 EFT Interactions of Dark Matter with Electroweak Bosons: Collider and Cosmological Probes, Present and Future

Speaker: Giulio Marino (Pisa University and INFN Pisa)

ECFA TALK.pdf

14:55 Hints for New Higgs Bosons in Associated Di-Photon Production

Speaker: Sumit Banik (Universität Zürich & Paul Scherrer Institut)

ECFA_2024.pdf

15:15 SUSY Parameter determination and dark matter phenomenology at future e+e- colliders

Speaker: Gudrid Moortgat-Pick (DESY and University of Hamburg)

gaugino-dm.pdf

15:35 Dark Matter searches in models with extended Higgs sector at lepton colliders

Speaker: JAYITA LAHIRI (II. Theoretical Institute for Physics, University of Hamburg)

Jayita.pdf

14:15 → 16:15 Parallel - WG2

Conveners: Dirk ZERWAS (DMLab and IJCLab), Fulvio Piccinini, Patrizia Azzi (INFN)

14:15 Tracking for the modified ILD detector concept at the FCCee

The ILD detector concept has originally been developed for the International Linear Collider (ILC). Detailed simulations gauged against the performance of prototype components have shown that ILD in its ILC incarnation is ideally suited to pursue the physics program of a linear Higgs factory as well as of a higher energy e+e− collider. Recently, the ILD collaboration has started to investigate how the detector concept would need to be modified in order to operate successfully in the experimental environment of a circular Higgs factory like for instance FCCee. In particular, the interaction region, or machine-detector interface (MDI), requires substantial changes to make room for accelerator elements and to withstand backgrounds. This contribution presents the progress in the adapted reconstruction to account for the modified tracking detectors and enable the assessment of the modified detector design in background and physics performance studies.

Speaker: Victor Schwan (DESY FTX-SLB)

ECFA_Tracking_ILD4FCC.pdf

14:35 Comprehensive Particle Identification Tool

This talk gives a brief overview of the novel reconstruction tool CPID (Comprehensive Particle Identification) covering its structure and module library, usage for physics analyses and as developer, as well as first applications.

Speaker: Uli Einhaus (KIT)

2024_10_09_3rd_ECFA_WS_CPID.pdf

14:55 Jet flavor tagging and particle flow by DNN with ILD full simulation

We are working on updating jet flavor tagging using Particle Transformer (ParT) from last year. We implemented b and c tagging feature and obtained a significant performance improvement from the previous software (also developed by the authors), LCFIPlus which was already reported at the previous workshop. We optimized parameters of the network and input structure to further improve the performance and investigating limitation with current network. Implementation of inference process to the ILD framework is also being done (to be finished by the workshop) to enable it to be used for physics analysis. We are also investigating strange tagging with ParT to enhance classification of jets as 5 kinds (b, c, g, s, ud) to be utilized to Higgs to ss analysis.
In addition, we are working on particle flow with GNN and Transformer. Initial study with GNN gives compelling performance with the current PandoraPFA algorithm, which will also be reported.

Speaker: Dr Taikan Suehara (ICEPP, The University of Tokyo)

241002-hlreco-ildsoftana-suehara.pdf

15:15 ML-based Particle Flow for CLD

We present an ML-based particle flow algorithm for the CLD detector. Particle candidates are built from hits and fitted tracks, which are represented as a graph. A geometric graph neural network is then trained using object condensation loss to reconstruct a set of particle candidates from the hits and tracks. In the second step, additional heads are used to estimate the energy and momentum of the candidates. Our algorithm improves over the baseline in terms of efficiency and energy resolution. We demonstrate the effectiveness of the approach using a dataset of 10-15 collimated particles resembling a jet at reconstructing their mass.

Speaker: Gregor Krzmanc (ETH Zürich)

MLPF.pdf

15:35 Transformer-based Jet Flavor Tagging in Full Simulation for CLD at FCC-ee

The precision study of the Higgs boson is a primary goal for future e+e- colliders. Accurate identification of its decay products is crucial for these measurements. Utilizing full simulation of proposed detector concepts provides a realistic estimate of the expected physics performance. In this talk, I will present the first results on jet flavor tagging in full simulation for the proposed CLD detector at FCC-ee, achieved using a transformer-based neural network.

Speaker: Sara Aumiller (Technical University of Munich (TUM))

ECFA-24_SaraAumiller.pdf

15:55 Machine Learning Techniques to Probe Heavy Neutral Leptons in the electron channel at FCC-ee

In place of traditional cut-and-count analyses, machine learning methods can provide powerful ways to analyse physics data. In this work, we present techniques involving boosted decision trees (BDT) and deep neural networks (DNN) to increase the existing projected 95% CL limits for the HNL discovery potential at the FCC-ee, specifically as the HNLs decay into the final state of an electron and two jets. Considering HNLs in the mass range of 10-80 GeV, with couplings $10^{-3}$ < $|U_{eN}|^2$ < $10^{-10}$, we report an increased sensitivity of up to two orders of magnitude in the couplings when compared to previous cut-and-count analyses.

Speaker: Pantelis Kontaxakis (pantelis.kontaxakis@unige.ch)

ECFA_Presentation_Kontaxakis.pdf

14:15 → 16:15 Parallel - WG3

Conveners: Felix Sefkow (Deutsches Elektronen-Synchrotron), Giovanni Marchiori (APC Paris), Dr Mary-Cruz Fouz (CIEMAT)

14:15 Beamstrahlung backgrounds in ILD at linear (ILC) and circular (FCCee) colliders

I will report on a comparison of beamstrahlung backgrounds at the ILC and FCCee, with an emphasis on the Time Projection Chamber and Vertex detector. The different Machine-Detector Interface designs and beam timing structures at the two colliders imply dramatic effects on detector backgrounds.

Speaker: Daniel Jeans (KEK / IPNS)

TPC-BG-ECFA2024.pdf

14:39 Performance of a Pixel Time Projection Chamber

A Time Projection Chamber (TPC) module with 32 GridPix chips was constructed and the performance was measured using data taken in a testbeam at DESY in 2021.
The GridPix chips each consist of a Timepix3 chip with integrated amplification grid and have a high efficiency to detect single ionisation electrons.
In the testbeam setup, the module was placed in between two sets of Mimosa26 silicon detector planes that provided external high precision tracking and the whole detector setup was slided into the PCMAG magnet at DESY.
The analysed data were taken at electron beam momenta of 5 and 6 $GeV/c$ and at magnetic fields of 0 and 1 Tesla(T).

The transverse and longitudinal diffusion coefficients were measured with high precision.
The tracking systematical uncertainties in xy (pixel plane) were measured to be smaller than 13 microns.

The $dE/dx$ or $dN/dx$ resolution for electrons in the 1 T data was measured.
The projected particle identification performance of a GridPix Pixel TPC in ILD at ILC was evaluated.
The expected pion-kaon separation for momenta in the range of 2.5-45.0 GeV/c is more than 4.5 sigma.

Other Pixel TPC analysis results will be presented: the single electron efficiency at high hit rates,
the characterisation of hit bursts and the resolution in the precision plane as a function of the incident track angle.

The results demonstrate the tracking and particle identification capabilities of a GridPix Time Projection Chamber and its potential at future colliders such as ILC (CLIC), CEPC, FCCee or EIC.

On behalf of: M. van Beuzekom, Y.Bilevych, K.Desch, S. van Doesburg, H.van der Graaf, F.Hartjes, J.Kaminski, P.M.Kluit, N.van der Kolk, C. Ligtenberg, G.Raven and J.Timmermans

Speaker: Peter Kluit (Nikhef)

PixelTPC_ECFA-kluit.pdf

15:03 A straw tracker for FCC-ee

We propose to perform R&D studies for a straw tracker that can be used as an outer tracker for the FCC-ee experiments. The straw tracker offers the advantage of a low material, a crucial factor in minimizing overall material budget of the tracker. With the capability to achieve a single-hit resolution of 100-120 microns per layer with O(100) layers in total, the straw tracker will play a pivotal role in pattern recognition and particle identification. Each individual straw serves as a standalone unit, facilitating easy removal of a channel in case of a broken sense wire. All charges produced in one single straw will remain in that unit. The electric field is radial symmetric and the hit position resolution is thus independent of the particle's incident angle. Furthermore, the adaptability of the straw tracker design is highlighted by its ability to accommodate straws with different radii in different detector regions.
We present simulation and optimization studies for a straw tracker using GEANT4 and gas mixture studies using Garfield. We will also present our prototype straw tracker and some studies performed using cosmic muons.

Speaker: Liang Guan (University of Michigan)

2024.10.9_Straw_tracker_FCCee_LG.pdf

15:27 Advancing Particle Identification in Helium-Based Drift Chambers: A Cluster Counting Technique Study through Beam Tests

While the ionization process by charged particles (dE/dx) is commonly used for particle identification, uncertainties in total energy deposition limit particle separation capabilities. To overcome this limitation, the cluster counting technique (dN/dx) leverages the Poisson nature of primary ionization, providing a statistically robust method for inferring mass information. Simulation studies using Garfield++ and Geant4 indicate that the cluster counting technique can achieve twice the resolution of the traditional dE/dx method in helium-based drift chambers. However, in real experimental data, finding electron peaks and identifying ionization clusters is extremely challenging due to the superimposition of signals in the time domain. To address these challenges, this talk introduces cutting-edge algorithms and modern computing tools for electron peak identification and ionization cluster recognition in experimental data. The effectiveness of the algorithms is validated through four beam tests conducted at CERN, involving different helium gas mixtures, varying gas gains, and various wire orientations relative to ionizing tracks. The tests employ a muon beam ranging from 1 GeV/c to 180 GeV/c, with drift tubes of different sizes and diameter sense wires. The data analysis results concerning the ascertainment of the Poisson nature of the cluster counting technique, the establishment of the most efficient cluster counting and electrons clustering algorithms among the various ones proposed, and the dependence of the counting efficiency versus the beam particle impact parameter will be discussed. Additionally, a study comparing the resolution obtained using the dN/dx and dE/dx methods will be presented.

Speaker: Dr Walaa Mohamed Abdelaziz Elmetenawee (INFN - Sezione di Bari)

ECFA24_Paris.pdf

15:51 The ARC compact RICH detector: reconstruction and performance

PID will be essential in FCC-ee experiments for precision studies of heavy-flavour physics and Z, Higgs, W, and top decays.
In this context, a novel RICH detector concept, named ARC (Array of RICH Cells), has been proposed.
The ARC detector is designed to operate over a momentum range of 1-40 GeV, using both $C_4F_{10}$ gas (or a more enviromentally-friendly equivalent) and Aerogel as radiators. The expected angular resolution of the ARC detector is on the order of milliradians, ensuring precise measurement of the Cherenkov angle.
The modular design of ARC includes identical cells, repeated to cover the entire external surface of the detector, with a radiator volume and a spherical mirror focusing the Cherenkov photons onto a SiPM photodetector plane. \
A pattern-recognition algorithm has been implemented for this geometry. The Cherenkov angle is reconstructed using the particle's trajectory provided by the tracking system. This process is subject to various uncertainties due to the unknown photon emission point, limited knowledge of the photon detection point due to the pixel size, and chromatic dispersion, that are currently under evaluation. A pattern recognition approach, using likelihood calculations and iterative mass hypothesis adjustments, is under development for use when there are multiple tracks per event passing through a cell or if there are other significant backgrounds to be handled. The latest results of these evaluations will be presented and their implications for the ARC detector's performance discussed.

Speaker: Serena Pezzulo (University of Genoa)

The ARC compact RICH detector.pdf

16:15 → 16:45 coffee break

16:45 → 18:25 Plenary

Convener: Jenny List (DESY)

16:45 Searches for LLPs

Speaker: Rebeca Gonzalez Suarez (Uppsala University (SE))

Paris-2024-RGS.pdf

17:05 Searches for new exotic scalars

Speaker: Prof. Aleksander Filip Zarnecki (University of Warsaw)

zarnecki_exscalar_ft_ecfa2024_v2.pdf

17:25 EW precision: 2-fermion final states ($\sqrt{s}=M_Z$ and beyond)

Speaker: Daniel Jeans (KEK / IPNS)

twoFsummary.pdf

17:45 CKM matrix elements from $W$ decays

Speaker: Uli Einhaus (KIT)

2024_10_09_3rd_ECFA_WS_WWCKM.pdf

18:05 Heavy quark fragmentation and hadronisation

Speaker: Loukas Gouskos (Brown University)

lg_bcfrag_ecfa_paris_2024_v1.pdf

18:30 → 21:00 Poster Session / Welcome Reception (at 19:00)

18:30 Measurements of $H \to \tau\tau$ properties at FCC-ee

The Future Circular Collider (FCC) stands at the forefront of the European Strategy for Particle Physics as the future Higgs factory. The $H \to \tau\tau$ decay, featuring a large branching ratio, clean identification at FCC-ee environment, and the possibility to reconstruct polarization information, is an excellent channel to measure Higgs properties. The CP nature of the Htautau coupling is of particular interest because the CP-odd component only appears in Higgs gauge couplings through loop effects, while it is allowed to be sizable in the Higgs couplings to fermions. This contribution shows recent progress in the experimental setup for the $H \to \tau\tau$ analysis and reports prospective results in both the ZH, $H \to \tau\tau$ cross section measurement and CP measurement, as well as the interpretation framework based on SM effective field theory.

Speaker: Matteo Presilla (KIT)

18:32 CPV measurement in HZZ (VBF) at 1 TeV ILC

We explore the possibility that CP symmetry is violated in Higgs boson's interactions with Z, assuming that Higgs is produced in ZZ-fusion, at 1 TeV ILC. CPV is generated via mixing of scalar and pseudoscalar states in 125 GeV mass eigenstate. 8 ab−1 of data collected with the ILD detector is simulated in the full simulation (background) and fast simulation of the detector response (signal). It is shown that the
mixing angle between scalar and pseudoscalar states can be measured with the statistical uncertainty of 3.8 mrad at 68% CL, corresponding to 1.44 ·10−5 for the parameter fCP, for measurement of the pure scalar state. This is the first result on sensitivity of an e+e− collider to measure fCP in vector boson fusion Higgs production vertex.

Speaker: Ivanka Bozovic-Jelisavcic (VINCA Institute of Nuclear Sciences)

18:34 ALLEGRO simulated performance

Calorimetry based on liquefied noble gases is a well proven technology that has been successfully applied in numerous high-energy physics experiments, such as DØ, ATLAS, and NA62. In addition to extreme radiation hardness, noble liquid calorimeters provide excellent energy resolution, linearity, stability, uniformity and timing properties at a reasonable cost. These attributes make it a strong candidate for future particle physics experiments - in both hadron and lepton colliders. Advances in printed circuit board (PCB) technology and manufacturing processes make it possible to add high granularity to the already impressive list of benefits of noble liquid calorimeters. By using multi-layer PCB's as read-out electrodes between the noble liquid and absorbers, we can build a calorimeter with almost arbitrarily high granularity. This in turn allows for four-dimensional imaging, machine learning algorithms and particle-flow reconstruction to be fully exploited.

ALLEGRO (A Lepton coLlider Experiment with Granular calorimetry Read-Out) is a detector concept proposed for FCC-ee whose R&D is ongoing for adapting noble liquid sampling calorimetry to an electromagnetic calorimeter. In this poster we will present some simulated performances of ALLEGRO.

Speaker: Tong LI (APC Paris, CNRS/IN2P3)

ECFA_workshop2024_TongLI.pdf

18:38 K4DetPerformance: A Framework for Tracking Performance Studies in Full Simulation Environments

K4DetPerformance is a framework designed to study tracking performance within full simulation environments. Initially developed for the CLD detector for FCC-ee, K4DetPerformance has now been integrated into the Key4hep software stack. Current efforts are focused on extending its applicability to other detectors.

The framework requires a complete simulation and reconstruction setup. It employs Condor for running simulations and reconstructions, uses FCCAnalyses for handling RDataFrame, and matches reconstructed tracks to simulated particles. The framework supports plotting options, including the ability to superimpose plots and ratios for comparative analysis.

K4DetPerformance provides a robust solution for tracking performance evaluation and has become an essential tool for detector performance studies across different detector models within the Key4hep software ecosystem.

Speaker: Gaëlle Sadowski (iphc)

k4DetPerf_poster_GaelleSadowski.pdf

18:40 SDHCAL evolution: Time integration and algorithmic improvements for the APRIL Particle Flow.

The SDHCAL (Semi Digital Hadronic Calorimeter) is a hadronic calorimeter for Particle Flow. It is proposed for future e+e- Higgs factories projects as a baseline for different detectors. A technological prototype has been built within the CALICE collaboration. This prototype is a sampling hadronic calorimeter using large GRPC (Glass Resistive Plate Chamber) as active medium with embedded readout electronics. The size of the GRPC prototype is 1 m². The readout PCB consists of 1 cm² copper pads on one side and 64-channel HARDROC readout chips on the other. Each chip processes the signal arriving on a 64 cm² square.
Sophisticated clustering algorithms that fully exploit the highly granular information to separate energy deposition from charged and neutral particles are required to achieve the best jet energy resolution for Particle Flow Algorithms (PFA). APRIL, a PFA based on the ARBOR concept, has been developed. The ARBOR concept reconstructs showers as spatial trees and APRIL is an implementation of this concept in the PandoraSDK framework.
To improve the separation of showers for the PFA, the use of time information can be useful. On the hardware side, this can be done with better than 100 ps time resolution by replacing single GRPC with multi-gap GRPC. On the software side, in order to take full advantage of the added time information, an adaptation of the PFA is also required. Work has been done to improve the SDHCAL reconstruction. The ILD detector has been used as a baseline for these studies. New methods for the reconstruction of the hadronic energy in the SDHCAL have been investigated. Improved energy corrections are currently being tested. Work is also progressing on cleaning the APRIL PFA and preparing it to become a time PFA.
The poster will describe the current SDHCAL prototype. The planned hardware evolution will be presented. It will focus on software improvements for hadronic shower reconstruction, including PFA and energy reconstruction. Potential improvements that can be achieved will be discussed.

Speaker: Tanguy PASQUIER (IP2I, Univ Lyon 1)

Poster_ECFA_final.pdf

18:42 Calorimetry simulations for the ALLEGRO FCC-ee detector

After LHC era, the Future Circular Collider is a very ambitious project for the next generation particle collider. The first stage of the project is circular electron-positron collider (FCC-ee). One of the proposed detectors for FCC-ee is general-purpose detector ALLEGRO. The calorimetry system of new detector consists of a high granular noble liquid electromagnetic calorimeter and a hadronic calorimeter with scintillating tiles using wavelength shifting fibers. The individual components of electromagnetic and hadronic calorimeter in the barrel and extended barrel regions will be introduced. ALLEGRO detector concept is fully implemented under FCC software, studies to optimise detector design and physics performance were made, simulations and calibration will be presented.

Speakers: Filomena Sopkova (Charles University), Filoména Sopková (Charles University)

Poster__ECFA_2024-2.pdf

18:44 QCD & Lund Jet Plane Studies at FCC-ee

This analysis explores the sensitivity of the strong coupling constant 𝛂s​ at the FCC-ee through studies based on R3/2 and the Lund Jet Plane (LJP). Preliminary results demonstrate the dependence of R3/2​ on 𝛂s​​, providing key insights into QCD measurements. For LJP studies, initial representations of primary and secondary LJPs are presented, utilizing clustering and declustering algorithms for the e+e- environment. Additionally, the potential of the LJP tool for jet tagging techniques at FCC-ee is emphasized.

Speakers: Lata Panwar (LPNHE), Lata Panwar (Laboratoire de physique nucléaire et des hautes énergies (LPNHE), Paris, France)

ECFAEarlyCareer_Oct2024.pdf

Poster-LPNHE_A1.pdf

Thursday 10 October

09:00 → 10:50 Plenary

Convener: Dirk ZERWAS (DMLab and IJCLab)

09:00 FCC: recent updates and goals/plans for contribution to ESPPU

Speaker: Frank Zimmermann (CERN)

FCC-ECFA-WS-Oct2024.pptx

09:30 Linear Colliders: recent updates and goals/plans for contribution to ESPPU

Speaker: Steinar Stapnes (CERN)

linear-colliders-ecfa-uploaded.pptx

10:00 US planning for a Higgs Factory

Speaker: Ritchie Patterson (Cornell)

ECFA-Oct-2024 v2-patterson.pdf

10:15 CEPC: status of the proposal, and plans

Speaker: Joao Guimaraes da Costa (IHEP)

20241010-ECFA-Paris-CEPC.pdf

10:30 Banquet information

Coupole.pdf

10:30 → 11:00 coffee break: Workshop Photo

11:00 → 13:00 Parallel - WG1-GLOB: ====> HTE+GLOB

Conveners: Alexander Grohsjean (CEA Saclay Irfu/SPP), Chris Hays (Oxford University), Fabio Maltoni Maltoni (UCL), JORGE DE BLAS (University of Granada), Jenny List (DESY), Junping Tian (University of Tokyo), Karsten Köneke (University of Freiburg), Marcel vos (IFIC - centro mixto U. Valencia/CSIC, Valencia, Spain), Patrick Koppenburg (Nikhef), Sven Heinemeyer (IFCA (CSIC-UC, Santander))

11:00 Non-universal probes of Higgs compositeness: New bounds and prospects for tera-Z

We study the leading loop-level phenomenology of composite Higgs models via the effective field theory of a strongly interacting light Higgs and top quark (SILH+TQ). We systematically analyze the renormalization group evolution (RGE) of tree-generated operators in the SILH+TQ scenario, finding large mixings of flavor non-universal operators into those affecting electroweak precision observables. Flavor non-universal effects are accounted for by examining three options for the top mixing. In the most phenomenologically viable case of a fully composite $t_R$, we show that the strongest bound on the natural parameter space comes from next-to-leading log running of the 4-top operator $(\bar t_R \gamma_\mu t_R)(\bar t_R \gamma^\mu t_R)$ into the Peskin-Takeuchi $T$ parameter. In general, we find that this 2-loop effect allows existing electroweak precision data to give better constraints on 4-top operators compared to high-energy probes from top production at the LHC. Independent of the top mixing, we find that a future tera-$Z$ machine has the potential to probe Higgs compositeness up to a scale of $m_* \gtrsim 25$ TeV.

Speaker: Ben Stefanek (King's College London)

stefanek_ECFA_2024_PDF.pdf

11:20 ZH angular measurements and anomalous CP-even & CP-odd HZZ couplings at future Higgs factories

The angular distributions in the $e^+e^- \to ZH \to f\bar{f}H$ process provide a new probe to the BSM physics on top of the signal strength, in particular useful when BSM physics induces anomalous couplings with new Lorentz structure. Those anomalous couplings result in changes in event shape that are highly dependent on the collision energies. In this study we perform full detector simulation of the ZH angular measurements and give prospects of the sensitivity to both CP-even and CP-odd anomalous HZZ couplings at future Higgs factories. We also present new ideas about the optimal collision energies which may improve significantly the sensitivity to anomalous couplings. The full simulation analyses are carried out based on the ILD detector concept at the International Linear Collider, however the methods in our study are generic and applicable to all future Higgs factories.

Speaker: Andrea Siddharta Maria

ECFA - Andrea Siddharta Maria.pptx

11:40 Prospects for New Discoveries Through Precision Measurements at e+e- Colliders

We systematically study potential effects of BSM physics in the $e^+ e^- \to Z H$ process. To this end, we include all relevant dimension-6 Standard Model Effective Field Theory operators and work to next-to-leading order (NLO) accuracy in the electro-weak coupling. We consider both polarized and unpolarized electron and positron beams and present results for $\sqrt{s}=240$, $365$ and $500$ GeV and emphasize observables where the NLO predictions differ significantly from the leading order (LO) results. At NLO, a sensitivity arises to operators that do not contribute at tree level, such as the Higgs trilinear coupling , CP violating operators, dimension-6 operators involving the top quark or anomalous Higgs-Z boson couplings, among many others. We compare the prospects of future $e^+e^-$ colliders to explore these new physics effects with measurements from the LHC, electron EDMs (for CP violating operators), and Z pole measurements.

Speaker: Dr Pier Paolo Giardino (University "Autonoma" of Madrid)

Talk.pdf

12:00 Projections for Higgs self-coupling measurements with double higgs production with ILD at multiple COM energies

As a milestone in the physics program of future lepton colliders, the process of double Higgs-strahlung ee → ZHH allows direct access to the Higgs self-coupling at energies above ≈ 450 GeV. The last full evaluation of measuring this process at a conter-of-mass energy of 500 GeV is more than 10 years old, and many of the reconstruction tools have received major improvements since, including flavor tagging using machine-learning and improved tagging of isolated leptons. This contribution will present the current status of the updated ZHH projections with the International Large Detector (ILD) assuming multiple center-of-mass energies between 500-600 GeV and incorporating state-of-the-art reconstruction tools. Furthermore, the interplay with single-Higgs measurements and the vvHH channel will be discussed, in particular in extended Higgs models. Furthermore, an outlook for this analysis until the input to the next European Particle Physics Strategy Update is given.

Speaker: Bryan Bliewert (Deutsches Elektronen-Synchrotron DESY)

ECFA_HTE3_ZHH_ILD_Bliewert.pdf

12:20 Sensitivity to detecting New Physics effects first in the trilinear Higgs coupling

The trilinear Higgs coupling (THC) offers a unique opportunity to probe the structure of the Higgs sector and to study the nature of the electroweak phase transition. It provides experimental access to the Higgs potential, the “holy grail” of Particle Physics, and should be a crucial target for future high-energy colliders. Extended Higgs sectors, featuring additional Higgs bosons, can give rise to a Strong First Order Electroweak Phase Transition (SFOEWPT), which could explain the observed baryon asymmetry. The parameter region yielding a SFOEWPT is often correlated with a sizeable deviation of the THC from the prediction of the Standard Model.
In this talk, I will present several examples of realistic Beyond-the-Standard-Model (BSM) scenarios in which large, observable, deviations occur in the THC, while other Higgs properties (e.g. its decay width to two photons or its hZZ coupling) would not exhibit sufficiently large effects to be detected with future precision measurements. For the concrete BSM scenarios investigated here it will be demonstrated that their behaviour under renormalisation-group running and their matching to appropriate EFTs is well compatible with the large effects in the THC. The findings presented here provide a strong motivation for running a future Higgs factory at a centre-of-mass energy of at least 500 GeV, in order to enable the measurement of the trilinear Higgs coupling in the Zhh production process.

Speaker: Dr Johannes Braathen (DESY)

Braathen_ECFA2024.pdf

12:40 Physics case for an e^+e^- collider at 500 GeV and above

In this talk I will discuss some highlights emphasising the physics case for running an e^+e^- collider at 500 GeV and above. In this context I will focus in particular on the experimental access to the Higgs potential via di-Higgs and (at sufficiently high energy) triple Higgs production. The information obtainable from Higgs pair production at about 500 GeV will be compared with the indirect information that can be obtained from a Higgs factory running at lower energies and with the prospects for the HL-LHC.

Speaker: Georg Weiglein (DESY)

ECFA_HFac_LC500_24.pdf

11:00 → 13:00 Parallel - WG1-SRCH

Conveners: Prof. Aleksander Filip Zarnecki (University of Warsaw), Rebeca Gonzalez Suarez (Uppsala University (SE)), Roberto Franceschini (Roma Tre University and INFN Rome)

11:00 Exploring the nature of heavy neutral leptons in final state distributions

Speaker: Jan Hajer (CFTP, IST, Universidade de Lisboa)

Exploring the nature of heavy neutral leptons in final state distributions

11:20 Heavy Neutral Leptons Search in a Realistic Neutrino Oscillation Model at FCC-ee

Speaker: Sofia Giappichini

ECFA_twoHNLs_241010.pdf

11:40 Probing the nature of HNL at lepton colliders

Speaker: Krzysztof Mekala (University of Warsaw / DESY)

Mekala_heavy_neutrinos_ECFA24.pdf

12:00 Searching for Heavy Neutral Leptons and measuring them with the IDEA detector at the FCC-ee

Speaker: Dr Nicolò Valle (INFN, Sezione di Pavia, Italie)

HNLecfaPoleselloValle-upl.pdf

12:20 Right-Handed Majorana Neutrinos at a e+ e- collider

Speaker: Jurina Nakajima (SOKENDAI/KEK)

ECFA2024_jurina_RHN.pdf

12:40 Leptophilic Z′ bosons at the FCC-ee

Speaker: José Zurita (IFIC - Univ. of Valencia and CSIC)

Zurita_ECFA_FCCee.pdf

11:00 → 13:00 Parallel - WG2

Conveners: Dirk ZERWAS (DMLab and IJCLab), Fulvio Piccinini, Patrizia Azzi (INFN)

11:00 Status of the Sherpa 3.0 event generator

I will review the status and latest developments of the Sherpa event generator and its application in particular to future Higgs/EW/Top factories. The newly released version 3.0 of Sherpa provides much needed upgrades while continuing the traditional focus of the framework on higher order corrections both in QCD and EW calculations that will be crucial for a successful physics program at a future lepton collider.

Speakers: Daniel Reichelt, Daniel Reichelt

ECFA_Paris_2024_DReichelt.pdf

11:20 Investigating New Physics contamination in luminosity measurements at future colliders

Several key observables of the high-precision physics program at
future lepton colliders will critically depend on the knowledge of the machine absolute luminosity. The determination of the luminosity relies on the knowledge of some process which is in principle not affected by unknown physics, so that its cross section can be computed within a well-established theory, like the Standard Model. Quantifying possible New Physics (NP) effects on such processes is therefore crucial. We present an exploratory investigation on possible NP contamination on reference processes and possible strategies to remove the uncertainties originating from such contamination.

Speaker: Francesco Pio Ucci (University of Pavia)

TalkUcci.pdf

11:40 WG2: Technical Benchmarks for Monte Carlo Generators

In this presentation, I will provide an update on the technical benchmarking of Monte Carlo generators. I will showcase some preliminary results and discuss the roadmap for their contribution to the final ECFA report.

Speaker: Alan Price (Jagiellonian University)

aprice_final.pdf

12:00 Beam-Induced Background Simulation Studies for the Cool Copper Collider

Beam-beam interactions constitute an important source of beam-induced background (BIB) at any $e^{+}e^{-}$ collider, with implications for the design and optimization of detectors at these machines and, ultimately, their physics reach. In this talk, we will present the status of BIB simulations for the Cool Copper Collider (C$^3$). We will report results for the simulation of incoherent $e^{+}e^{-}$ pair production, hadron photoproduction and halo muon production from interactions with collimator material, and discuss technical challenges with these simulations relevant for any $e^{+}e^{-}$ machine. Using full detector simulation for the SiD detector concept and utilizing the Key4hep framework, we assess the impact of these backgrounds on the occupancy of the various sub-detector systems, most notably the vertex detector, and evaluate the effects of variations in the bunch time-structure of the beams. Finally, we will report the technical progress towards a full, out-of-time pileup mixing procedure of these backgrounds with hard-scatter events using well-established iLCSoft tools. We will conclude by discussing the compatibility of the C$^3$ beam configuration with ILC-like detectors, as well as lessons learned in the process that are useful for background simulation and detector studies at future $e^{+}e^{-}$ colliders.

Speaker: Lindsey Gray (Fermi National Accelerator Laboratory)

C3ECFA3_LindseyGray_10102024.pdf

12:20 Luminosity Spectra (on zoom)

Speakers: Jürgen Reuter (DESY Hamburg, Germany), Thorsten Ohl (University of Wuerzburg)

ohl-paris2024.pdf

12:40 Bunch Structure Studies at C3

The Cool Copper Collider (C3) accelerator concept has been found to be a compact, energy efficient accelerator design that is sufficient for studying the Higgs Boson in great detail. Studies to simultaneously optimize the scientific and environmental impact of C3’s luminosity production have been underway for some time and here we present studies of these re-optimized machine configurations in a full GEANT simulation of the SiD detector concept. Some of these scenarios involve smaller bunch separations than the nominal 5.25ns (250 GeV) or 3.5ns (550 GeV) C3 bunch spacing, amplifying out-of-time pileup effects. We will evaluate background effects at both center-of-mass energies. We will consider these scenarios from the perspective of detector occupancy, performing full simulation of in-time and out-of-time beam induced backgrounds, discussing the merits and drawbacks of each configuration.

Speaker: Dimitris Ntounis (Stanford University & SLAC National Accelerator Laboratory)

C3_bkg_DN_ECFA_2024.pdf

11:00 → 13:00 Parallel - WG3

Conveners: Felix Sefkow (Deutsches Elektronen-Synchrotron), Giovanni Marchiori (APC Paris), Dr Mary-Cruz Fouz (CIEMAT)

11:00 R&D on Noble Liquid Calorimeter for Future Collider Experiments

A novel concept for the high granular noble liquid calorimeter optimised for the measurements of electrons and photons at $e^+e^-$ Higgs factories, namely for the Future Circular Collider FCC-ee, will be introduced. The concept is motivated by an excellent performance, stability, uniformity and linearity of the response observed with the past and current noble liquid calorimeters. The design of the electromagnetic calorimeter with straight multilayer readout electrodes allow for fine segmentation which is crucial for advanced reconstruction techniques, e.g. machine learning algorithms, four-dimensional imaging and particle flow. The ongoing R&D studies on the readout electrodes will be presented. The results of the measurements with the first prototypes will be compared with the simulations. The optimization studies of the mechanical structure of the calorimeter and the cryostat, along with the results of the tests on the absorber prototype will be shown. The steps towards the beam test prototype will be discussed. The integration of the calorimeter design in the key4hep software will be presented, together with the expected performance of calorimeter system.

Speaker: Fares DJAMA (CPPM)

AllegroEcal_Djama.pdf

11:18 Design and performance of the calorimeter system for ALLEGRO FCC-ee detector concept

Allegro, one of the detector concepts under study for FCC-ee, is currently in its design and optimization phase. This contribution aims to introduce Allegro’s calorimeter system, offering an overview of the baseline technologies planned for its two calorimeter systems: a highly granular noble-liquid electromagnetic calorimeter and a hadronic calorimeter with scintillating-light readout using wavelength shifting fibers.
To evaluate the performance of calorimeters, test different detector geometries, and fine-tune reconstruction algorithms such as topological clustering, Monte Carlo simulations of single particles are used. Preliminary results from performance studies with the standalone HCal and combined ECal+HCal calorimeters are presented, shedding light on the promising capabilities of this newly introduced detector concept for FCC-ee. In addition to these design-focused analyses, we briefly introduce our inquiries into the potential use of machine-learning approaches for particle identification and detector calibration.

Speaker: Michaela Mlynarikova (CERN)

ECFA workshop ALLEGRO talk.pdf

11:36 Estimation of the fluxes in ILD calorimeters at FCC-ee

The calorimeter systems of the detectors near future HET factories must operate in very different running conditions: machine backgrounds, dominant cross-sections and luminosities vary by several orders of magnitude as a function of the center-of-mass energy. A determination of the expected fluxes in the calorimeters is mandatory to scale the electronics, power dissipation and data output.
Using a new versatile tool, a set of fluxes is evaluated from detailed simulations: energy, time and occupancy spectra, as well as secondary distributions, power, dynamic ranges in energy and time, and data fluxes, given reasonable hypotheses on the electronics.
Preliminary results will be presented and discussed for the ILD detector at the FCC-ee.

Speaker: Vincent BOUDRY (LLR - CNRS, École polytechnique/IPP Paris)

2024-10-10_CaloFlux.pdf

11:54 Challenges ahead of the ILD SiW-ECAL

The traditional purpose of the ECAL of the ILD experiment is to measure neutrals (especially photons, but also the interacting neutral hadrons) while tracking the charged particles for particle flow algorithms.
A highly granular Silicon-Tungsten ECAL (SiW-ECAL) is particularly suited for these tasks.
The SiW-ECAL faces many technical challenges: some remain to be tackled, while new ones, such as a precise timing, still need to be fully evaluated.
It is proposed here to make a review of the art on all these issues.

Speakers: Adrian Irles (IFIC (CSIC/UV) Valencia), Roman Poeschl (LAL Orsay), Vincent BOUDRY (LLR - CNRS, École polytechnique/IPP Paris)

2024-10-10@3rdECFA_SiWECAL_VB_v2.pdf

12:12 Dual-Readout Fibre-Sampling Calorimeter for next lepton collider

Precision measurements at future lepton colliders require excellent energy resolution, especially in multi-jet events, to successfully separate Z, W, and Higgs decays. The dual-readout method, which uses both scintillation and Cherenkov light, has proven to be a promising solution. This technique provides two independent energy measurements of the hadronic shower, allowing event-by-event compensation for the electromagnetic fraction fluctuations.
Different detector geometries were investigated using small prototypes qualified on beam and data-tuned simulations. Among these, a design employing capillary tubes stands out for its ease of assembly, high accuracy, and cost-effectiveness. In this context, we present HiDRa, the 65×65×250 cm$^3$ High-Resolution Highly Granular Dual-Readout Demonstrator. Its main goal is to evaluate performance in terms of linearity and energy resolution with a high-energy hadron beam.
This talk will discuss the solution adopted to build the demonstrator. We will present the latest simulation results for this prototype and compare them with recent test beam data. In addition, we will show the latest performance obtained in the simulation with the "4π" detector geometry, implemented using the capillary tube design.

Speaker: Ruggero Turra (INFN Milano)

turra_dual_readout.pdf

12:36 Particle Flow Algorithm for Long Crystal Bar ECAL

The precise measurements of the Higgs, W and Z boson properties at future electron-positron collider will provide critical tests of the Standard Model (SM) and are essential in the exploration of new physics beyond the SM (BSM). To distinguish the hadronic decays of W and Z bosons, a 3-4% jet energy resolution is required. The particle flow approach, which aims to measure individual particles in jets using imaging calorimeter system, is a very promising method to achieve the unprecedented jet energy resolution.

A novel electromagnetic calorimeter (ECAL) with orthogonally arranged crystal bars has been proposed. The crystal bar design is expected to provide optimal intrinsic energy resolution and three-dimensional shower information for the particle flow algorithm (PFA). Additionally, the long bar design will significantly reduce the cost of electronics. However, the crystal bar ECAL also presents challenges, such as the potential ambiguity problem for multiple particles due to the perpendicular arrangement of crystal bars in adjacent layers and increased shower overlap from different particles caused by the larger $R_M$ and $X_0/λ_I$ for crystals.

This report presents recent progress on the new PFA dedicated to the crystal bar ECAL. The ambiguity problem has been addressed through the implementation of multiple optimized pattern recognition approaches, while the issue of shower overlap has been mitigated by an energy splitting module. The development of the PFA takes into account various aspects including electronics, heat dissipation, mechanical support, and digitization processes of ECAL. The algorithm’s performance, including a boson mass resolution of approximately 3.9%, will be demonstrated. These results underscore the potential of the proposed ECAL design and the PFA in enhancing detector capabilities and reconstruction methodologies for future electron-positron collider experiments.

Speaker: Yang Zhang (The Institute of High Energy Physics of the Chinese Academy of Science)

ECFA_CyberPFA.pdf

13:00 → 14:15 lunch break

13:15 → 14:15 ECR session: White Paper input to EPPSU: ECR Session 1

Discussion on Early-Career Researcher's* White Paper input to the European Particle Physics Strategy Update (EPPSU).

Please subscribe to eppsu-ecr@cern.ch and join our Mattermost channel to get all updates on this. If you have questions about the organisation, please ask on Mattermost or direct them to eppsu-ecr-organisers@cern.ch.

Discussion and active participation over Zoom will be possible.

*: For the EPPSU, the ECR definition is: <10 years after PhD OR non-permanent position. The focus will be on the European ECRs perspective, but ECRs beyond Europe are welcome to contribute to the discussions.

Zoom information:
https://cern.zoom.us/j/64136592945?pwd=AbaOkHJbAiLOjoNKJJFoE1oJxKfMmQ.1

Meeting ID: 641 3659 2945
Passcode: 072067

Convener: Magdalena Vande Voorde (KTH Royal Institute of Technology (SE))

Evening_session_recording.mp4

Lunch_session_recording.mp4

13:15 The European Particle Physics Strategy Update and the role of Early-Career Researchers (talk)

• Introduction of the EPPSU from an ECR perspective
• Plan for an ECR White Paper input to the EPPSU
• Structure of the sessions

Speaker: Armin Ilg (University of Zürich)

EPPSU ECR White Paper input.pdf

13:30 Who are we? (interactive)

Getting to know audience with live survey

Speakers: Emanuela Musumeci (IFIC CSIC/UV), Magdalena Vande Voorde (KTH Royal Institute of Technology (SE))

Survey_QR_code.png

"Who are we?" live survey

13:45 What is important to us for the future of particle physics in Europe? (discussion)

Brainstorming on topics that we want to address in the ECR White Paper input to the EPPSU (discussion)

Speakers: Emanuela Musumeci (IFIC CSIC/UV), Magdalena Vande Voorde (KTH Royal Institute of Technology (SE))

14:15 → 16:15 Parallel - WG1-HTE: ===> HTE+PREC

Conveners: Chris Hays (Oxford University), Fabio Maltoni (UCLouvain/Unibo), JORGE DE BLAS (University of Granada), Jenny List (DESY), Karsten Köneke (University of Freiburg), Patrick Koppenburg (Nikhef)

14:15 Tau polarisation measurement at a future Higgs Factory

I will discuss the measurement of the tau polarisation at a Higgs Factory in the process e+ e- -> tau+ tau-, both at the nominal centre-of-mass energy and the radiative return to the Z. Aspects of required detector performance will also be discussed.

Speaker: Daniel Jeans (KEK / IPNS)

taupol-ecfaParis-talk.pdf

14:35 Tau Physics at FCCee

The data sample of $6⋅10^{12}$ Z boson decays expected to be produced at the FCC-ee offers unprecedented opportunities for the precise measurement of physics observables. One of the areas in which large improvements are foreseen is the determinations of tau lepton properties (lifetime, leptonic/hadronic widths, mass), allowing for key tests of lepton universality. These measurements will benefit from a low-background environment, initial-state energy-momentum constraints and high Lorentz boost. They present strong challenges to match the 𝑂($10^{−5}$) stat uncertainties, raising strict detector requirements and novel experimental methods to limit systematic effects. In this presentation we will explore the measurement of the tau polarisation at the FCCee, focusing on some of the main experimental inputs and systematics with full simulation studies to emphasize the capabilities of FCCee for tau identification. The performance of different tau lepton reconstruction approaches in some of the leading decay modes ($\tau^{\pm}\rightarrow\pi^{\pm}\nu$, $\tau^{\pm}\rightarrow\pi^{\pm}\pi^{0} (\rho) \nu$, $\tau^{\pm}\rightarrow \pi^{\pm}\pi^{\mp}\pi^{\pm}(a_{1})\nu$) will also be discussed.

Speaker: Maria Cepeda (CIEMAT)

TausAtFCCee.pdf

14:55 Prospects for constraining light-quark electroweak couplings at Higgs factories

Electroweak Precision Measurements are stringent tests of the Standard Model and sensitive probes to New Physics. Accurate studies of the Z-boson couplings to the first-generation quarks could reveal potential discrepancies between the fundamental theory and experimental data. Future e+e- colliders running at the Z pole and around the ZH threshold would be an excellent tool to perform such a measurement, unlike the LHC where hadronic Z decays are only available in boosted topologies. The measurement is based on comparison of radiative and non-radiative hadronic decays. Due to the difference in quark charge, the relative contribution of the events with final-state radiation (FSR) directly reflects the ratio of decays involving up- and down-type quarks. Such an analysis requires proper modeling and statistical discrimination between photons coming from different sources, including initial-state radiation (ISR), FSR, parton showers and hadronisation. In our contribution, we show how to extract the values of the Z couplings to light quarks and present the estimated uncertainties of the measurement.

Speaker: Krzysztof Mekala (University of Warsaw / DESY)

Mekala_light_quarks_ECFA24.pdf

15:15 Expected Measurements of the Higgs boson mass and ZH production cross sections at sqrt(s) =240 and 365 GeV, at the Future e+e- Circular Collider (FCC-ee)

At the Future e+e- Circular Collider a long data taking period is also foreseen at the ttbar production threshold and slightly above, up to sqrt(s)=365 GeV, with more than 300 000 ZH events expected at these energies. We study the precision which can be reached with this dataset on the Higgs mass, and combine it with the measurement obtained with the same recoil mass technique in the e+e- and mu+mu- final state, at srqt(s)=240 GeV, which are also presented in detail. We present also the precision which can be obtained on the total ZH cross section measurement at sqrt(s)=240 and 365 GeV.

Speaker: Gregorio Bernardi (APC Paris CNRS/IN2P3)

ECFA.2024-Bernardi-Higgs-V1.pdf

15:35 A New Method for Measuring the Higgs Mass at Linear Colliders

The Higgs mass as one of the fundamental parameters in the Standard Model has been already measured with a precision of 140 MeV with the data collected so far at the LHC. However in some cases of looking for small deviations from the SM, current precision or projection of the Higgs mass measurement at the LHC or HL-LHC may not be enough. One prominent example is for the SM prediction of the Higgs partial decay width H → W W ∗ or H → ZZ∗, in which the Higgs mass uncertainty becomes one of the leading sources of parametric theory error. It is expected that at future e+e- colliders the Higgs mass precision can be significantly improved by the “recoil mass method”, at least statistically. This research proposes a new method which may complement to the recoil mass method in terms of systematic errors. The new method employs the signal channel of Higgs decaying to a pair of fermions, in particular τ leptons, or 2 quarks bb and makes use of transverse momentum conservations alone instead of the 4-momentum conservation in the recoil mass method. The key experimental observables will be the momentum directions of tau leptons without any input from energy measurement, and the momentum directions can possibly
be measured by reconstructing the decaying vertex of the tau leptons. This new method can in principle be applied at linear colliders and the LHC as well. Another possible improvement is in the case of τ → 3 − prongs, to reconstruct the decay vertex and use it to directly obtain the direction of the τ with the IP. This method was studied by performing realistic detector simulation and physics analysis with the ILC and ILD frameworks. This method can be used in conjunction with other methods to improve the Higgs mass measurements at colldiers.

Speaker: Thomas Berger

Slides_ECFA_meeting_BERGER_Thomas.pdf

Slides_ECFA_meeting_BERGER_Thomas.pptx

15:55 Top properties from the threshold scan

In this contribution we report on progress in the prospects for the measurement of top quark properties in a scan of the center-of-mass energy through the top quark pair production threshold. Several aspects of the threshold scan are studied in greater detail, including in particular the experimental selection in a new study with a parameterized simulation of the IDEA detector response in the FCCee environment. Updated projections are presented for all projects of the precision that can be achieved in the top quark mass and width determination. A new approach is explored for the extraxtion of the top quark Yukawa coupling by measuring the WbWb cross section above the tt production threshold.

This study was perfomed in the framework of the focus topic "ttbar threshold" in the ECFA Higgs/top/EW factory study". .

Speaker: Matteo Defranchis (CERN)

ECFA_workshop_2024_ttbar_AM.pdf

14:15 → 16:15 Parallel - WG1-SRCH: SRCH+FLAV

Conveners: Prof. Aleksander Filip Zarnecki (University of Warsaw), Fabio Maltoni Maltoni (UCL), JORGE DE BLAS (University of Granada), Jenny List (DESY), Patrick Koppenburg (Nikhef), Rebeca Gonzalez Suarez (Uppsala University (SE)), Roberto Franceschini (CERN)

14:15 Long-lived particle searches with the ILD experiment

Speaker: Jan Klamka (University of Warsaw (PL))

jklamka_3rdECFA.pdf

14:35 Long-lived particles from exotic Higgs decays at the FCC-ee

Speaker: Magdalena Vande Voorde (KTH)

LLPsExoticHiggs_ECFAWS.pdf

14:55 Search for LLP in Z decays in association with a prompt photon at Tera-Z / Z boson decay into a light scalar boson and a photon: study of the FCC/CEPC sensitivities

Speaker: Giacomo Polesello (INFN, Sezione di Pavia, Italie)

fcc_alp_ecfa.pdf

15:15 Impact of detector and accelerator conditions on the stau-pair production sensitivity at future Higgs Factories

Speaker: María Teresa Núñez Pardo de Vera (DESY)

StauSearches_ECFAWS24.pdf

15:35 Hitting the Thermal Target for Leptophilic Dark Matter at Future Colliders

Speaker: Cari Cesarotti (MIT)

ecfa_cesarotti.pdf

15:55 Time-Dependent Precision Measurement of $B_s^0\to \phi\mu^+\mu^-$ Decay at the FCC-$ee$

Speaker: Tsz Hong Kwok (University of Zurich)

3rdECFA_AnsonKwok.pdf

14:15 → 16:15 Parallel - WG2

Conveners: Dirk ZERWAS (DMLab and IJCLab), Fulvio Piccinini, Patrizia Azzi (INFN)

14:15 Monte Carlo Productions for Full Simulation Studies

Large scale Monte Carlo studies are only possible with sufficient computing power. To make efficient use of these distributed resources, the DIRAC framework, and its instance for future High Energy Lepton Collider Studies, iLCDirac, offers the end users and production managers a user friendly interface. While studies for the ILC and CLIC have made use of iLCDirac for years, this presentation will detail how it was now adopted also for FCCee studies. The presentation will give a brief overview of the interface to end users and production managers, show how the system was employed in recent months to provide Monte Carlo samples for the ECFA Higgs/Electroweak/Top studies, and how these samples can be used. Recent developments about the integration of the full Key4hep software stack, and more specifically about the introduction of FCCee production workflows, will also be discussed.

Speaker: Andre Sailer (CERN)

241010_sailer_dirac_ecfa.pdf

14:35 Reconstruction Tools in Key4hep

Full simulation studies are an essential tool to estimate the physics
reach for future colliders. Developing optimal reconstruction tools
for future colliders is one of the main goals for Key4hep. To properly
estimated performances, it is of particular importance to correctly
treat beam-induced backgrounds and estimate how they affect
reconstruction efficiencies and resolutions for sophisticated
algorithms such as for particle flow clustering, which is a key
ingredient for optimal jet energy resolutions. This presentation will
cover the developments for and the integration of background overlay
processor, the interface to Pandora PFA for arbitrary detectors and
related algorithms, such as digitisers, and which issues were
discovered and resolved along the way.

Speaker: Swathi Sasikumar Kollassery (CERN)

Swathi_ECFA.pdf

14:55 End-to-end ML-based reconstruction for FCC-ee

We present an ML-based end-to-end algorithm for adaptive reconstruction in different FCC detectors. The algorithm takes detector hits from different subdetectors as input and reconstructs higher-level objects. For this, it exploits a geometric graph neural network, trained with object condensation, a graph segmentation technique. We apply this approach to study the performance of pattern recognition in the IDEA and CLD detectors using hits from the pixel vertex detectors and the drift chamber. We also build particle candidates from detector hits and tracks in the CLD detector. Our algorithm outperforms current baselines in efficiency and energy reconstruction and allows pattern recognition in the IDEA and CLD detector. This approach is easily adaptable to new geometries and therefore opens the door to reconstruction performance-aware detector optimization.

Speaker: Dolores Garcia

ECFA_DG_10_2024.pdf

15:15 Developing and evaluating kink finding method with BSM models in ILD

Charged Long Lived Particles can produce a characteristic "kinked" track when they decay. Since the ILD-TPC can measure more than 200 hits along a particle's trajectory, it is a very powerful tool to detect such kinked tracks. In this study, based on full detector simulation, a new improved kink finding method was developed for the TPC. The potential to constrain different BSM scenarios will also be presented.

Speaker: Jurina Nakajima (SOKENDAI/KEK)

ECFA2024_jurina_kink.pdf

15:35 Evaluating strange-tagging performance for SiD fast- and full-simulation

In this work we will present first results on the comparison of strange-quark jet tagging for full-detector and Delphes fast simulation using the SiD detector concept. Strange tagging plays a crucial role in the complete exploration of the second-generation Yukawa couplings and in probing new physics frontiers with the strange quark, inaccessible at the LHC. At future electron-positron (e+e-) Higgs factories, strange-tagging (s-tagging) is tightly connected with detector technologies and layout optimization. Existing studies have demonstrated the potential for s-tagging at future Higgs factories but have relied either on full simulation or a fast simulation approach assuming different detector concepts and without evaluating their relative performance. In this study, we compare, for the first time, the performance of the ParticleNet algorithm for s-tagging using both full- and fast-simulation Higgs samples for a common detector, SiD. The analysis will provide insights into the strengths and limitations of fast simulation in reproducing the detailed detector effects captured by full simulation. Our findings will inform the optimization of detector design and analysis strategies for future e+e- colliders.

Speaker: Dimitris Ntounis (SLAC)

Hss-ECFA-2024_DN.pdf

15:55 Jet Flavour Tagging at FCC-ee with a Transformer-based Neural Network: DeepJetTransformer

Jet flavour tagging is crucial in experimental high-energy physics. A tagging algorithm, DeepJetTransformer, is presented, which exploits a transformer-based neural network that is substantially faster to train.

The DeepJetTransformer network uses information from particle flow-style objects and secondary vertex reconstruction as is standard for $b$- and $c$-jet identification supplemented by additional information, such as reconstructed V$^0$s and $K^{\pm}/\pi^{\pm}$ discrimination, typically not included in tagging algorithms at the LHC. The model is trained as a multiclassifier to identify all quark flavours separately and performs excellently in identifying $b$- and $c$-jets. An $s$-tagging efficiency of $40\%$ can be achieved with a $10\%$ $ud$-jet background efficiency. The impact of including V$^0$s and $K^{\pm}/\pi^{\pm}$ discrimination is presented.

The network is applied on exclusive $Z \to q\bar{q}$ samples to examine the physics potential and is shown to isolate $Z \to s\bar{s}$ events. Assuming all other backgrounds can be efficiently rejected, a $5\sigma$ discovery significance for $Z \to s\bar{s}$ can be achieved with an integrated luminosity of $60~\text{nb}^{-1}$, corresponding to less than a second of the FCC-ee run plan at the $Z$ resonance.

Speaker: Freya Blekman (IIHE, Vrije Universiteit Brussel (BE))

S-tagging-and-beyond-DeepJetTransformer-ECFA-Blekman-10Oct2024.pdf

14:15 → 16:15 Parallel - WG3

Conveners: Felix Sefkow (Deutsches Elektronen-Synchrotron), Giovanni Marchiori (APC Paris), Dr Mary-Cruz Fouz (CIEMAT)

14:15 GRAiNITA a new type of calorimeter

GRAiNITA is a new type of calorimeter where volume high-Z scintillator grains are immersed in a high-density transparent liquid. The multiple refraction of the light on the grains ensures the stochastic confinement of the light. The readout is dealt with WLS fibers. A small prototype has been tested in beam at CERN and some preliminary results will be shown.

Speaker: Marie-Hélène Schune (IJCLab)

GRAiNITA_ECFAworkshop_Oct2024_MHS.pdf

14:39 µ-RWELL muon system and pre-shower for FCC-ee

This presentation provides a full review of the R&D for the µ-RWELL technology for the FCC-ee application, with the report
on update on the detector optimization, on the studies to improve the ASIC, and on the evaluation of the proposed performance within the IDEA framework.

In the IDEA experiment, µ-RWELL technology is proposed for the muon systems and the pre-shower. This MPGD exploits a compact manufacturing technique and provides competitive performance. This design keeps the cost of the entire system affordable and, benefiting from the ongoing technological transfer within the MPGD community will maintain a strong connection with industries.

Optimizing the readout electronics channels is needed to advance this technology's state of the art and meet the IDEA requirements. Ongoing activities focus on readout segmentation with various schemes, such as strips, capacitive sharing, and top-readout. Performance comparisons between new TIGER electronics and the APV-25 will be reported. These inputs will be used to define the final configuration for the detector proposal.

Moreover, the activities include simulations for both the detector and the experiment: a simulation of the µ-RWELL with TIGER or APV electronics is performed, and tuning with experimental data will improve their reliability and provide a useful tool to define the
characteristics of a new ASIC. Additionally, a simulation of the µ-RWELL muon system in the IDEA simulation framework is implemented in DD4HEP. This powerful tool connects the gas detector community to the needs of the FCC experiment.

Speaker: Riccardo Farinelli (INFN Bologna (IT))

Farinelli_ECFA_µRWELL_IDEA.pdf

15:03 Preshower simulation of IDEA detector

The IDEA detector has been selected for the FCC due to its innovative design, featuring a central tracker enclosed in a superconducting solenoidal magnet, a Preshower detector, and a dual readout calorimeter. In the IDEA detector, the µRWELL technology; a single-amplification stage resistive Micro Pattern Gaseous Detector (MPGD), based Pre-shower and muon detectors are integrated with modular design of active tile area 50 × 50 cm2 and pitch width of 400µm. The H → γγ decay is a favorable channel to detect H which is the primary function of the electromagnetic calorimeter (ECAL). But the false signal from the short-lived neutral π0 decay into low energy photons can be picked as an H signal when it decays into two closed low energy photons which collectively result in a high energy register in ECAL. This limitation can be resolved by a fine-granular Pre-shower, which can distinguish between two extremely close, low-energy independent photons and hence contribute to minimizing uncertainty in H physics. The endcap and barrel Pre-shower are placed before the ECAL to overcome this deceptive signal problem.
The current talk presents the status of the Preshower’s uni-layer barrel having 32 sides and endcap implementation for the IDEA detector using DD4hep in k4geo. Future directions for endcap detector geometry builders are also suggested, along with a Preshower design potential discussion to prevent conflicts with dual readout calorimeters.

Speaker: Nitika Nitika (University of Udine)

Nitika_ IDEA preshower-1.pdf

15:27 Towards an asymmetric detector at HALHF

The Hybrid Asymmetric Linear Higgs Factory (HALHF) proposes a shorter and cheaper design for a future Higgs factory. It reaches a √s = 250 GeV using a 500 GeV electron beam accelerated by an electron-driven plasma wake-field, and a conventionally-accelerated 31 GeV positron beam. Assuming plasma acceleration R&D challenges are solved in a timely manner, the asymmetry of the collisions brings additional challenges regarding the detector and the physics analyses. An ILD-based, asymmetric detector was implemented in Geant4 to cope with the forward boosted topologies and accommodate the beam backgrounds. This contribution will show the first physics results using a fully simulated asymmetric detector for HALHF, and compare the performance against some flagship Higgs Factory analyses.

Speaker: Antoine Laudrain (DESY)

241010-AntoineLaudrain-ECFA_HET2024-Detector_for_HALHF.pdf

15:51 Embedded FPGAs for Data Processing in Future e+e- Detectors

Embedded field programmable gate array (eFPGA) technology allows the implementation of reconfigurable logic within the design of an application-specific integrated circuit (ASIC), enabling fast and flexible machine learning (ML) in readout electronics. Detectors at a future e+e- Higgs factory can benefit from increased intelligence throughout the data pipeline, for reduced data rates, faster inference, and increased efficiency. Furthermore, eFPGAs can be designed with a variety of open-source frameworks, lowering the cost of entry for institutional groups. This work presents recent developments of eFPGAs for collider applications, namely the design and tapeout of two eFPGAs and their ability to implement ML for at-source pixel readout. Next steps in eFPGA development are discussed, along with applications of eFPGA technology to other data processing tasks at Higgs factories and beyond.

Speakers: Julia Gonski (SLAC National Accelerator Laboratory (US)), Julia Lynne Gonski (SLAC National Accelerator Laboratory (US))

1010_jgonski_ecfaworkshop_efpgas.pdf

16:15 → 16:45 coffee break

16:45 → 18:15 Plenary

Convener: Patrizia Azzi (INFN)

16:45 The Higgs/EWK/top factory challenge for detectors

Speaker: Felix Sefkow (Deutsches Elektronen-Synchrotron)

ECFA-Paris-DetectorChallenge-FS20241010.pdf

17:10 Simulation of HET factory detectors

Speaker: Alvaro Tolosa Delgado (CERN, European Organization for Nuclear Research)

ecfa24_detector_simulation_atd_t.pdf

17:35 Reconstruction for HET factory experiments

Speaker: Frank Gaede (DESY)

gaede_key4hep_reco_ecfa24.pdf

18:30 → 19:40 ECR session: White Paper input to EPPSU: ECR session 2

Discussion on Early-Career Researcher's* White Paper input to the European Particle Physics Strategy Update (EPPSU).

Please subscribe to eppsu-ecr@cern.ch and join our Mattermost channel to get all updates on this. If you have questions about the organisation, please ask on Mattermost or direct them to eppsu-ecr-organisers@cern.ch.

Discussion and active participation over Zoom will be possible.

*: For the EPPSU, the ECR definition is: <10 years after PhD OR non-permanent position. The focus will be on the European ECRs perspective, but ECRs beyond Europe are welcome to contribute to the discussions.

Zoom information:
https://cern.zoom.us/j/64136592945?pwd=AbaOkHJbAiLOjoNKJJFoE1oJxKfMmQ.1

Meeting ID: 641 3659 2945
Passcode: 072067

Conveners: Armin Ilg (University of Zürich), Leonhard Reichenbach (CERN / University of Bonn)

Evening_session_recording.mp4

Lunch_session_recording.mp4

18:30 Further topics for ECR White Paper input? (discussion)

Speaker: Leonhard Reichenbach (CERN / University of Bonn)

18:40 Ranking of topics (interactive)

We rank the proposed topics to gauge the interest

Speakers: Emanuela Musumeci (IFIC CSIC/UV), Magdalena Vande Voorde (KTH Royal Institute of Technology (SE))

Live_survey_QR_code.png

"Ranking of topics" live survey

18:55 Potential statements (discussion, if time allows)

Speaker: Armin Ilg (University of Zürich)

19:05 Formation of Working Groups

• Call for WG organisers
• Call to everyone to give input to WGs

Speaker: Armin Ilg (University of Zürich)

19:15 Summary and next steps towards ECR White Paper input to EPPSU (talk)

Speakers: Armin Ilg (University of Zürich), Leonhard Reichenbach (CERN / University of Bonn), Magdalena Vande Voorde (KTH Royal Institute of Technology (SE))

EPPSU ECR White Paper input_Summary.pptx

20:00 → 22:00 Conference Dinner: Aperitif at 20.00 / Sitting at 20:20 / Dinner starts at 20:30 / tables of 10 persons, get organized in advance if you wish !

Friday 11 October

09:00 → 10:45 Plenary

Convener: Giovanni Marchiori (APC Paris)

09:00 Generators and Theory developments needed for HET physics

Speaker: Carlo Carloni Calame (INFN, Pavia, Italy)

carloni.pdf

09:30 Towards detectors for HET factories / tracking and vertexing systems

Speaker: Fabrizio Palla (INFN Pisa)

ECFA 3rd workshop Paris 2024.pptx

09:55 Towards detectors for HET factories / calorimeter and PID systems

Speaker: Nicolas Morange (IJCLab)

2024-10-09_Calorimeters_PID.pdf

10:20 Towards detectors for HET factories / electronics, mechanics, integration

Speaker: Thomas Bergauer (HEPHY Vienna (OEAW))

2024-10-11_ECFA-HET-WS_Bergauer_electronics-mechanics.pdf

10:45 → 11:15 coffee break

11:15 → 12:45 Plenary

Convener: Patrick Koppenburg (Nikhef)

11:15 Determination of the Higgs self-coupling

Speaker: Junping Tian (University of Tokyo)

Hself_ECFA_20241011.pdf

11:35 Top mass and electroweak couplings

Speaker: Matteo Defranchis (CERN)

MD_tt_ECFA.pdf

11:55 Poster prizes and short talks by winning posters

12:20 Summary of WG3 sessions and plans

Speaker: Dr Mary-Cruz Fouz (CIEMAT)

WG3Summary_ECFAParis2024_red2.pdf

12:45 → 14:00 lunch break

14:15 → 16:15 Plenary

Convener: Christos Leonidopoulos (FNAL)

14:15 WG1 (physics potential): HTE subgroup report/plans

Speakers: Karsten Köneke (University of Göttingen), Karsten Köneke

2024-10-11 ECFA Paris Workshop - WG 1 Higgs Top Electroweak.pdf

14:30 WG1 (physics potential): PREC subgroup report/plans (on zoom)

Speaker: Ayres Freitas (University of Pittsburgh)

Slides

14:45 WG1 (physics potential): GLOB subgroup report/plans

Speaker: Marcel vos (IFIC - centro mixto U. Valencia/CSIC, Valencia, Spain)

GLOB_summary.pdf

15:00 WG1 (physics potential): FLAV subgroup report/plans

Speaker: Stephane Monteil (Laboratoire de Physique de Clermont - UCA/IN2P3)

ECFA_Paris_FLAV_summary_monteil_2024.pdf

15:15 WG1 (physics potential): SRCH subgroup report/plans

Speaker: Roberto Franceschini (CERN)

ECFA Paris WG1-SRCH report plans - Franceschini.pdf

15:30 Next steps and timelines for ECFA Report; approval process

Speakers: Aidan Robson (University of Glasgow), Christos Leonidopoulos (FNAL)

ecfaHiggs_reportPlans_paris_v1fixlink.pdf

15:45 Discussion: what is missing; how to engage in ESPPU process

Speaker: Paris Sphicas (Athens/CERN)

2024-10-09-HET-Wkshp-Closeout.pdf

16:00 Closeout

Speaker: Gregorio Bernardi (APC Paris CNRS/IN2P3)

Farewell-2.pdf