CP2023

12 févr. 2023, 12:00 → 17 févr. 2023, 18:00 Europe/Paris

Amphi (École de Physique des Houches)

Currently, particle physics badly fails to explain the matter-antimatter asymmetry of the Universe. This workshop aims at discussing this problem from different perspectives. The diverse experimental programs searching for CP violation beyond the Standard Model and their prospects will be discussed, in relation with the theoretical approaches to baryogenesis and leptogenesis.

Scientific scope

• Collider probes of CP violation
• Low-energy precision probes of CP violation, EDMs and the like
• Long-baseline neutrino probes of CP violation
• Lepton number violation
• Models of baryogenesis and leptogenesis

A mini-school with the following invited lectures will introduce basic theoretical aspects: 

• CP Violation, Baryogenesis and Leptogenesis (Julia Harz)
• Effective Field Theories and CP violation (Adam Falkowsky)

Local Organization Committee

Mathieu Guigue, Guillaume Pignol and Stéphanie Roccia

International Advisory Committee

Susan Gardner, Tsuyoshi Nakaya, Marie-Hélène Schune

CP2023_first_circular.pdf

CP2023_second_circular.pdf

PXL_20230214_104506482.jpg

dimanche 12 février

Logistic: Welcome and Registration

19:30 Dinner

lundi 13 février

Lectures: Welcome

Président de session: Guillaume Pignol (LPSC)

Welcome_CP2023.pdf

Experiments: Colliders 1

1 CP violation at colliders

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

CPV_at _Colliders_monteil.pdf

2 BSM CP violation searches at LHCb

Orateur: Francesca Dordei (INFN, Cagliari (IT))

dordei.pdf

10:20 Break

Experiments: Colliders 2

3 BSM CP violation searches at Belle II

Up to now, the Belle II experiment has collected about the same amount of data as BaBar and the plan is to collect 50 times more. New physics can affect the phase of the amplitudes and consequently the measured CP violation parameters. There are two main complementary approaches: overconstraining the SM parameters in the precision measurements of the high-statistics tree-level B decays or searching for the deviations in the rare B decays where BSM effects are expected to be more pronounced. Compared to the hadron-hadron experiments, Belle II benefits from clean event topology which is essential for B decays including neutral particles.

Orateur: Radek Zlebcik (Charles University)

CP2023_zlebcik.pdf

Experiments: EDM 1

4 Interpreting Electric Dipole Moments

Orateur: Jordy de Vries (Nikhef)

CP2023_LesHouches_EDMs.pdf

5 Electric dipole moments of free charged particles

Orateur: Philipp Schmidt-Wellenburg (Paul Scherrer Institute)

srEDM_v2.pdf

srEDM_v2.pptx

12:20 Lunch

Experiments: EDM 2

6 EDM of atoms and nuclei

Orateur: Skyler Degenkolb (Universität Heidelberg)

7 Neutron EDM

Orateur: Skyler Degenkolb (Universität Heidelberg)

8 Search for the muon electric dipole moment using the frozen-spin technique

At the Paul Scherrer Institute we are developing a high precision instrument to measure the electric dipole moment (EDM) of the muon. The presence of a permanent EDM in an elementary particle would imply a violation of time invariance and the combined symmetry of Charge-Parity (CP). While the Standard Model of particle physics allows for a large CP-violating phase, it also predicts EDMs that are too small to be measured in the near future. However, many extensions to the Standard Model permit large CP-violating phases that could lead to large EDMs and, at the same time, potentially explain the observed baryon asymmetry of the Universe. Recent developments, such as the tensions in the magnetic anomaly of the muon and the electron, as well as hints of lepton-flavor universality violation in B-meson decays, have made the search for a muon EDM a topic of particular interest. The experiment at PSI will employ the frozen-spin method to suppress the anomalous precession of the muon spin, allowing for a sensitivity that cannot be achieved with conventional g-2 muon storage rings. With this technique, the expected statistical sensitivity for the EDM after one year of data taking is 6 x 10^-23 e·cm with the p = 125 MeV/c muon beam available at PSI. This work presents the muon EDM experiment at PSI, with a focus on the quantitative analysis of systematic effects that could mimic the EDM signal.

Orateur: Chavdar Dutsov

cut_orbit.mp4

Dutsov_muEDM_CP2023.pdf

muEDM_experiment_animation.mp4

muedm_leshouches_presentation.pptx

9 The commissioning of the MORA experiment

Searching for CP-violation in nuclear beta decay: Commissioning of the MORA apparatus at IGISOL The "Matter’s Origin from RadioActivity" (MORA) project focuses on ion manipulation in traps and laser orientation methods for the searches for New Physics (NP) in nuclear beta decays, looking for possible hints to explain the matter-antimatter asymmetry observed in the Universe. Located in Finland within the JYFL Accelerator Laboratory, the IGISOL facility delivers the right ion beam for the initial phase of the MORA experiment: The Mg23+ it provides is an ideal candidate to extract the so-called D correlation parameter which is sensitive to Time reversal violation and, according to the CPT theorem, to CP violation. The D parameter could be sensitive to the existence of lepto-quarks which are hypothetical gauge bosons occurring in the theories of the baryogenesis. By using an innovative in-trap laser polarization technique, we will be able to reach a sensitivity below 10^-4 on D. This sensitivity should allow us to probe not only NP but also the Final State Interaction process. The first tests with Mg23+ have been conducted in the IGISOl facility, after offline commissioning carried out using a Na23+ spark source. An efficient trapping process has been achieved up to 11s. Despite a large contamination of the radioactive beam with the stable Na23, around 30h of data have been registered using a trapping cycle of 3s and alternating 1h run with cloud laser polarizations (sigma +, sigma -) and without. The analysis is currently on-going. In this poster, the different steps of the offline and online commissioning will be presented.

Orateur: Pierre DELAHAYE (GANIL)

MORA_les Houches.pptx

15:50 Break

Experiments: 0nubb

10 Theoretical Overview of Double Beta Decay

I will discuss theoretical aspects of and recent developments in double beta decay. Focussing on the neutrinoless mode, I will review its role in our understanding of neutrinos and models of lepton number violation as the origin of light neutrino masses. I will attempt to elucidate connections with models of baryogenesis, specifically leptogenesis and I will describe the impact of an observation of neutrinoless double beta decay on the viability of baryogenesis mechanisms. Finally, I will also highlight the potential of the two-neutrino double beta decay mode to probe new physics.

Orateur: Frank Deppisch (University College London)

deppisch-cp2023-les-houches.pdf

11 Neutrino-less double beta decay overview

Orateur: Yoann KERMAIDIC (IJCLab)

Revue_double_beta_CP_YoannKermaidic.pdf

12 BINGO, towards the meV level of the neutrino mass scale

Neutrinoless double-beta decay is a hypothetic nuclear process which, in case of its observation, would provide important information about the nature of neutrino and will demonstrate the lepton number violation. Scintillation bolometers are one of the most promising technology for 0v2b decay search: low-temperature particle detector in joint with a cryogenic light detector. BINGO (Bi-Isotope 0v2b next-generation observatory) is a project which proposes several innovative technologies for future tone-scale bolometric experiments aimed at a dramatical background reduction in the region of interest thereby increasing the sensitivity to 0v2b. Experimental results obtained both above and underground will be presented.

Orateur: Vladyslav Berest (DPhP/IRFU/CEA)

BEREST_cp2023_bingo.pdf

13 Towards the NNBAR Experiment at the European Spallation Source

The European Spallation Source (ESS) in Lund, currently under construction, is designed to be the most powerful neutron source in the world. Taking advantage of the unique potential of the ESS, the NNBAR collaboration has proposed an experimental program to search for baryon number violation (BNV) due to neutron (n) – antineutron ( ̄n) conversions. This process could explain the observed asymmetric abundances of matter and antimatter in our known universe after baryogenesis. The general aim for the planned experimental campaign at the ESS is to reach an increase in sensitivity of three orders of magnitude over the current limit, obtained at a previous attempt. The BNV process may occur as free neutrons propagate via ballistic motion to a detector, where the anti-neutrons will annihilate and be detected via their multi‐pion decay signature. An overview on the present state of the work on the NNBAR experiment is given with special focus on the neutron optics and the detector system.

Orateur: Richard Wagner (Institut Laue-Langevin)

202302_NNBAR_CP2023.pdf

19:30 Dinner

mardi 14 février

Lectures: Effective Field Theory 1

Welcome_CP2023.pdf

14 Effective Field Theory 1

Orateur: Adam Falkowski (IJCLab)

LesHouches_23-02 lecture 1.pdf

10:30 Break

Theory

15 The shift-invariant orders of an ALP

Usually, effective field theories (EFTs) for axion-like particles (ALPs) are built assuming a shift symmetry for the ALP due to the global U(1) Peccei-Quinn (PQ) symmetry that is at the heart of the axion mechanism. However, it is generally believed that global symmetries, in particular axion shift symmetries, can only be approximate. Therefore, it is important to include shift-breaking interactions in the EFT description and find a clear way to implement the different power countings of the shift-conserving and shift-breaking sectors. Focusing on the flavorful effective Yukawa couplings to Standard Model fermions, I will present Jarlskog-like flavor invariants which act as order parameters for shift symmetry breaking of the axion. In this description, shift-breaking couplings are characterized in an explicit and flavor-invariant way and it is straightforward to give different power countings to the shift-conserving and shift-breaking sectors. I will discuss properties of the invariants like their CP parities, enabling us to make non-trivial connections between conservation of CP in the theory and an almost conserved shift-symmetry for the ALP. Finally, I will discuss examples of matching UV theories to the invariants and how they can be used to identify shift-breaking contributions in observables.

Orateur: Jonathan Kley (DESY)

CP2023_ShiftInvariantALPs.pdf

16 CP violating invariants in SMEFT

The Standard Model Effective Field Theory (SMEFT) is a framework that incorporates in a fairly model-independent way possible deviations from the Standard Model (SM). The additional terms it contains, in the form of higher-dimensional operator, may be include new sources of CP violation that could spoil the delicate CKM mechanism characterizing the SM. We argue that the best way to capture such additional sources is via quantities that are invariant under unitary flavor rotations. This realization leads to the unanticipated result that a good fraction of the new sources first appear in observables at a order higher than expected. For those that do show up at the expected order, we study the conditions that would make their size comparable to the SM CP violation.

Orateur: Emanuele Gendy Abd El Sayed (DESY)

LesHouches_EG.pdf

17 Conférence photo

Orateur: Mathieu Guigue (LPNHE Sorbonne Université)

PXL_20230214_104506482.jpg

12:30 Lunch

Theory

18 A late baryogenesis in an ekpyrotic-like universe with a hidden CP violation

Two-brane universes are among the cosmological models of interest such as ekpyrotic models. It is then a major concern to constrain these scenarios. In the last two decades, it has been theoretically demonstrated that matter exchange between branes can occur and can be a way to test these scenarios. Thus, neutron disappearance (reappearance) toward (from) a hidden brane has been recently tested with short-baseline reactor experiments (MURMUR, STEREO) used as competitive passing-through-walls neutron experiments to search for hidden neutrons. Here, we introduce an ekpyrotic-like model in which the matter (respectively antimatter) of our brane is coupled with the matter (respectively antimatter) of the hidden brane. However both couplings are supposed to break the CP invariance through the bulk thus leading the baryogenesis to occur lately after the electroweak epoch. The theoretical and experimental outcomes, and issues of such an approach are discussed.

Orateur: Michaël Sarrazin (Institut UTINAM, CNRS/INSU, UBFC)

2BBaryogenesis.pdf

19 CP violation and neutrinos

Orateur: Jonathan Kriewald (LPC Clermont)

JK_CP2023.pdf

Poster session

20 USSA characterization

Poster

Orateur: Anthony Lejuez

Poster_SF.pdf

21 Towards a better measurement of the CP violation phase with Hyper-Kamiokande

Poster

Orateur: Claire Dalmazzone

PosterCP2023LastVersion.pdf

22 Leptonic CPV phases: impact for LFV Higgs & Z-boson decays and CP asymmetries

Poster

Orateur: Emanuelle Pinsard

CP_Poster_Pinsard.pdf

23 CP violation and γ angle measurement in decay B- → D°(→Ksπππ°)K- (Generalized GGSZ method)

Poster

Orateur: Jessy Daniel

Poster_CP2023_v2.pdf

24 CsM Based Monitoring of a Current Source

Poster

Orateur: Judith Vankeirsbilck

CP2023_Poster.pdf

25 Mapping of the magnetic field in the n2EDM experiment

Poster

Orateurs: Kseniia Svirina (LPSC, Université Grenoble Alpes), Thomas Bouillaud

poster_LesHouches_v3.pdf

26 The ENUBET experiment

Poster

Orateur: Leon Halić

poster.pdf

27 Searching for CP-Violation in Nuclear Beta Decay: MORA first data analysis

Poster

Orateur: Luis Miguel Motilla Martinez

MORA_poster_AS_PSI-2.pdf

28 The commissioning of the MORA experiment

Poster

Orateur: Sacha Daumas-Tschopp

poster_les_Houches.pdf

29 Flavoured Leptogenesis in a Minimal Type-I+II Seesaw Mechanism

Poster

Orateur: Sreerupa Chongdar

daybreak_poster_a0-3.pdf

30 Testing neutron to hidden neutron oscillations with Ultra-Cold Neutrons Beams

Poster

Orateur: William Saenz

nnprime_poster.pdf

19:30 Dinner

mercredi 15 février

Lectures: Cosmology 1

Welcome_CP2023.pdf

31 Cosmology 1

Orateur: Dr Julia Harz (Technical University of Munich (TUM))

10:30 Break

Experiments: Neutrino oscillation 1

32 Review of CP violation in long-baseline neutrino experiments

Orateur: Sara Bolognesi (CEA Saclay)

bolognesi.pdf

33 NOvA

NOvA is a long-baseline neutrino oscillation experiment based at the Fermi National Accelerator Laboratory, USA. Utilizing two functionally-identical liquid scintillator tracking calorimeters placed 810 km apart, NOvA observes the appearance of electron (anti)neutrinos and the disappearance of muon (anti)neutrinos in the muon (anti)neutrino-dominated NuMI beam. By observing these (anti)neutrino oscillations, NOvA is probing several key questions in physics of neutrino oscillations including the neutrino mass ordering, leptonic CP violation phase 𝛿𝐶𝑃, the larger neutrino mass splitting Δ𝑚232, and the mixing angle 𝜃23. The most recent three-flavor neutrino oscillation results from NOvA will be presented.

Orateur: Pierre Lasorak (Sussex University)

20230215_NOvAOsc_LesHouches_Lasorak.pdf

34 Overview of the T2K Experiment

Orateur: Evan Goodman (University of Glasgow)

T2K_Overview_Goodman.pdf

12:30 Lunch

Lectures: Effective Field Theory 2

Président de session: Adam Falkowski (IJCLab)

Welcome_CP2023.pdf

35 Effective Field Theory 2

Orateur: Adam Falkowski (IJCLab)

LesHouches_23-02.pdf

19:30 Dinner

jeudi 16 février

Lectures: Cosmology 2

Welcome_CP2023.pdf

36 Cosmology 2

Orateur: Dr Julia Harz (Technical University of Munich (TUM))

10:30 Break

Theory

37 Overview leptogenesis

Orateur: Stéphane Lavignac (IPhT Saclay)

Lavignac_CP2023.pdf

38 Leptogenesis via a first-order phase-transition

Sterile Neutrinos are an attractive explanation for the masses of Standard Model neutrinos. They may also explain the asymmetry between matter and antimatter in our Universe. We will discuss a scenario in which these sterile Neutrinos acquire a time-dependent (Majorana) mass during a first-order phase-transition. This out-of-equilibrium process may lead to matter-antimatter asymmetry in the lepton sector, which is converted into baryon asymmetry via sphalerons.

Orateurs: Rémi Faure (Institut de Physique Théorique (CEA Saclay, Paris)), Rémi Faure (IPhT)

CP2023_RemiFaure.pdf

CP2023_RemiFaure.pptx

39 Implications of A_4 modular symmetry on neutrino mass, mixing and leptogenesis with linear seesaw

Motivated by the crucial role played by the discrete flavour symmetry groups in explaining the observed neutrino oscillation data, we consider the application $A_4$ modular symmetry in the linear seesaw framework. The basic idea behind using the modular symmetry is to minimize the necessity of the inclusion of extra flavon fields having specific vacuum expectation value (VEV) alignments. The breaking of flavor symmetry takes place when the complex modulus $\tau$ acquires VEV. The main issue of the perplexing vacuum alignment is avoided, the only requirement is a certain kind of mechanism which can fix the modulus $\tau$. Linear seesaw in this framework is realized with six heavy $SU(2)_L$ singlet fermion superfields and a weighton in a supersymmetric framework. The non-trivial transformation of Yukawa couplings under the $A_4$ modular symmetry helps to explore the neutrino phenomenology with a specific flavor structure of the mass matrix. We discuss the phenomena of neutrino mixing and show that the obtained mixing angles and CP violating phase in this framework are compatible with the observed $3\sigma$ range of the current oscillation data. In addition, we also investigate the non-zero CP asymmetry from the decay of lightest heavy fermion superfield to explain the preferred phenomena of baryogenesis through leptogenesis including flavor effects.

Orateur: Rukmani Mohanta (University of Hyderabad)

CP2023-RM.pdf

12:20 Lunch

Gala

vendredi 17 février

Logistic: Checkout

Experiments: Neutrino oscillation 2

40 DUNE: Status, progress and plans

The Deep Underground Neutrino Experiment (DUNE) is a flagship-international project in particle physics and one of the most ambitious neutrino beam experiments ever conceived, hosted by the United States DOE national laboratory, Fermilab. DUNE will play an essential role in studies of neutrino mass ordering, CP violation, and precise measurements of neutrino mixing parameters, as well as in the search for proton decay and supernova neutrinos. This experiment will use four 17 kt modules of LarTPCs (Liquid Argon Time Projection Chamber) detectors. This technology uses planes of parallel wires connected to a potential difference in liquid argon to reconstruct particles with precision comparable to a fully electronic bubble chamber. DUNE will consist of a far detector and a near detector exposed to the world's most intense neutrino beam originating from the Long Base Neutrino Facility (LBNF). Two prototypes have been built at CERN, which will not only serve as a test bed for engineering design and construction techniques, but will also provide a set of key measurements for the far-future DUNE detector. In this talk I will overview the Project with emphasis on the status of the construction, physics performance, and the demonstration of the DUNE technology at CERN.

Orateur: Maritza Delgado Gonzalez (University & INFN Milano-Bicocca)

DUNE.pdf

41 Hyper-Kamiokande: the road to measure the CP-phase in the neutrino sector

The next generation neutrino oscillation experiment, Hyper-Kamiokande, will consist of a 260 kt underground water-Cherenkov far detector located 295 km from the upgraded J-PARC neutrino beam of 1.3 MW. The primary goal of the experiment is the detailed study of neutrino oscillations and the precise measurement of the CP-violating phase. The latter is one of the main goals of the project and requires both flux and cross-section systematic uncertainties to be significantly reduced. To that end, the project will also count on a series of detectors closer (near and intermediate) to the neutrino beam will be deployed at various off-axis locations. In this presentation, an overview of the status of the entire project and a summary of all the activities toward the precise measurement of the CP-violating phase will be shown.

Orateur: Pablo Fernández (DIPC)

cp2023_v1.pdf

42 Measuring $\delta_{\rm CP}$ and constraining lepton flavour models at ESSnuSB

ESSnuSB is an upcoming accelerator based experiment in Sweden to study neutrino oscillation. The main aim of this experiment is to measure the leptonic CP phase $\delta_{\rm CP}$ by probing the second oscillation maximum. This experiment is also capable to test the viability of different lepton flavour models based on their prediction of the CP phase. In this presentation, I will discuss the sensitivity of ESSnuSB to measure the CP phase and also its capability to constrain the parameter space of a set of lepton flavour models.

Orateurs: Monojit Ghosh, Dr Monojit Ghosh (Ruder Boskovic Institute)

talk_LesHouches_logo (1) - 2023-02-16T232918.702.pdf

10:40 Break

Experiments: Neutrino oscillation 3

43 CP Violation Sensitivity in Future Long-Baseline Experiments

Our pursuit of novel physics may be advanced significantly by neutrinos. Neutrino oscillations have so far provided the only particle physics evidence for new physics beyond the standard model (BSM), making it an ideal area to investigate new physics scenarios. Recently, there have been a lot of interests in situations such as Non-Standard Neutrino Interactions (NSI) with matter and the existence of a fourth sterile neutrino. Leptonic CP violation is quite crucial in addition to the CP violation coming from the quark sector. Many ongoing and future long-baseline (LBL) experiments are going to determine the leptonic CP phase. Latest results show slight tension between T2K and NO$\nu$A in the measurement of standard model (SM) CP phase. We get tantalizing hint that BSM phase could severely impact the clean determination of SM CP phase. In fact from our analysis, we were able to resolve this discrepancy in T2K and NO$\nu$A with NSI. Next, we studied the CP phase for two of the futuristic LBL experiments: T2HK and DUNE in presence of dual NSIs arising from $e-\mu$ and $e-\tau$ sectors. In addition to that we also discuss the mass hierarchy in presence of both the NSI constraints.

Orateur: Anjan Giri (IIT Hyderabad)

CP2023-Giri.pdf

Lectures: Conclusions

Welcome_CP2023.pdf

44 Connecting conclusions

Orateur: Mikhail Shaposhnikov (EPFL)

Les_Houches2023_forpdf.pdf

45 Farewell

Orateur: Stéphanie Roccia

CP2023.pdf

12:30 Lunch

Logistic: Departure to Geneva airport