The 53rd Rencontres de Moriond session devoted to ELECTROWEAK INTERACTIONS AND UNIFIED THEORIES will be held in La Thuile from Saturday March 10th to Saturday March 17th, 2018.
La Thuile is a pleasant winter sport resort located in the Italian Alps, at 1450 m alt., about 120 km from Geneva. The nearest international airport is Geneva (Switzerland).
Since its foundation in 1966 by Jean Tran Thanh Van, the Rencontres de Moriond bring together theorists and experimentalists for in-depth discussions on recent findings and new ideas in elementary particle physics in a pleasant, relaxed and intimate atmosphere.
The meeting is intended to promote fruitful collaboration between experimentalists and theorists and between various institutions by bringing together a limited number of physicists and astrophysicists in beautiful and inspiring surroundings.
This session is devoted to electroweak interactions and to unified theories.
The Rencontres de Moriond are sponsored by
A critical reexamination of the assumptions used in the extraction of Vcb
from B->Dlv leads to unexpected results. The same approach can be used for the SM prediction of R(D).
TBA
Very rare decays at LHC
Measurement of CPV in charm at LHC
In my talk, I will try to address three questions:
(1) From a model builder's perspective, why does it make sense to consider the common origin of the neutral and charged current B-anomalies?
(2) Where is the new mass scale and what are the main model building blocks?
(3) Which are the most relevant non-observations to be tackled by a successful model?
Rare decays of known hadrons are sensitive probes for deviations of the dynamics with respect to the Standard Model one.
In this contribution we review the status of the rare b to sll transitions
as studied in b-hadrons produced in pp collisions at the LHC.
We examine gauged flavour models that could account for the anomalies in B physics
In the Standard Model (SM), the coupling of the electroweak gauge bosons to the leptons is lepton flavour universal. Tests of this property constitute sensitive probes for new physics models that violate lepton flavour universality. Recent tests of lepton universality in rare $b\to s\ell\ell$ decays and semileptonic $b\to c\tau\bar{\nu}_\tau$ transitions have shown some tensions with the precise SM predictions. The LHCb experiment is ideally suited for lepton universality tests in $B$-decays due to its large acceptance, high trigger efficiencies and excellent tracking and particle identification capabilities. Recent results on lepton flavour universality at the LHCb experiment will be presented.
I will present a model able to accommodate the recent experimental hints of lepton-flavor non-universality in B decays while, at the same time, providing an explanation to the Standard Model flavor hierarchies. The model contains a rich spectrum of new states at the TeV scale that can be probed by the high-pT experiments at the LHC, and predicts interesting low-energy signatures that could be tested in the near future.
The b->sll and b->ctaunu processes recently observed by the LHCb collaboration have exhibited a coherent set of deviations from the SM predictions. These anomalies might be well explained by leptoquarks (LQ) at the mass scale of O(1)TeV. In this talk, recent CMS searches for LQ will be reviewed, in light of the B-anomalies, and discuss about future prospect.
The LHCb measurement of the μ/e ratio RK indicates a deficit with respect to the Standard Model prediction, supporting earlier hints of lepton universality violation observed in the RK ratio. We show that the RK and RK() ratios alone constrain the chiralities of the states contributing to these anomalies, and we find deviations from the Standard Model at the 4σ level. This conclusion is further corroborated by hints from the theoretically challenging b → sμ+μ− distributions. Theoretical interpretations in terms of Z′, lepto-quarks, loop mediators, and composite dynamics are discussed. We highlight their distinctive features in terms of the chirality and flavour structures relevant to the observed anomalies.
The BESIII experiment at the Beijing Electron Positron Collider(BepcII) accumulated the world's largest e+ e- collision samples at 3.773 and 4.178 GeV. From analyses of D^{0(+)}-> K l+ nu and Ds+ -> l+ nu decays, we determine the CKM mattrix element |Vcs|, The form factors of D^{0(+)} semi-leptonic decays f_{K^{+(0)}}, the Ds+ decat constants f_{D_{s}^{+}}. The measured |Vcs| is important to test the unitarity of the CKM matrix, while f_{K^{0(+)}} and f_{D_{s}^{+}} to calibrate the LQCD calculations. We also report the Lepton Universality test in D-> pi l nu decays.
The decay K+->pi+nunu with a very precisely predicted branching ratio of less than 10^-10 is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at CERN SPS is designed to measure the branching ratio of the K+->pi+nn with a decay-in-flight technique, novel for this channel. NA62 has taken data firstly in 2016 with the aim to reach the SM sensitivity, it has then collected 10 times more statistics in 2017 and a similar amount of data is expected from the 2018 run. The preliminary result on K+->pi+nunu from the full 2016 data set is presented and prospects for future developments reviewed.
The purpose of the J-PARC KOTO experiment is to study the $K_L\rightarrow \pi^0 \nu \bar{\nu}$ decay.
This rare decay is known as a “golden mode” to search for new physics beyond the Standard Model (SM) because it violates the CP symmetry directly, it is strongly suppressed in the SM (BR ~ $3\times10^{-11}$)[1], and its theoretical uncertainty is small (~2%).
The upper limit of the branching fraction of this decay was given as $2.6\times 10^{-8}$ (90% C.L.) by the KEK E391a experiment[2].
In 2013, we had our first physics run for 4 days and achieved a comparable sensitivity as the E391a result.[3]
In 2015, we performed a physics run and collected 20 times the amount of data as that of the 2013 run.
The analysis status of the 2015 run data will be presented in this talk.
Reference :
[1] A. J. Buras, D. Buttazzo, J. Girrbach-Noe and R. Knegjens, J. High Energy Phys. 1511, 033 (2015).
[2] J. K. Ahn et al., Phys. Rev. D 81, 072004 (2010).
[3] J. K. Ahn et al., Prog. Theor. Phys. 021C01 (2017).
The talk will discuss the challenges in top physics and theory bottlenecks to achieve high precision measurements.
Measurements of the top quark mass obtained by the ATLAS and CMS experiments in proton-proton collisions at the LHC for centre-of-mass energies of 7, 8 and 13 TeV are presented. The mass of the top quark is measured using several methods and channels, including the reconstructed invariant mass distribution of the top quark and shapes of kinematic observables from top quark decay products. Measurements of the top-quark pole-mass based on the inclusive and differential top-anti-top production cross sections and observables based on the differential cross section in the top-pair plus 1 jet channel are also discussed.
This presentation will cover recent results in the top quark sector from the CDF and DZero experiments in proton-antiproton collisions at a centre-of-mass energy of 1.96 TeV at the Tevatron. The topics include the final combinations of the forward-backward production asymmetry and of the top quark mass, as well as a limited selection of individual results.
Measurements and searches are presented of association top production processes (ttV and tV) in pp collisions at sqrt(s) = 13 TeV recorded by CMS and ATLAS. ttW is measured in the two same-sign lepton channel, obtaining an expected (observed) significance of 4.5 (5.3) standard deviations in the CMS analysis and (3.4) 3.9 in the ATLAS analysis. ttZ associated production is measured in the three and four lepton channel with a significance of above 5 standard deviations. tZq is measured in the three lepton channel with an observed (expected) significance of 3.1 (3.7) sigmas in the CMS analysis and 4.2 (5.4) in the ATLAS one. tW is measured in the opposite-sign electron-muon channel with a precision of 10% by CMS and in the opposite-sign dilepton channel with a precision of 30% by ATLAS.
We report on the status of the precision measurements of electroweak parameters at CMS. The effective weak mixing angle sin^{2}_{\theta} is extracted by measuring the forward-backward asymmetry in di-lepton events near the Z boson mass region. The first observation of electroweak production of same-sign W boson pairs in proton-proton collisions is also reported.
I will summarize Tevatron electroweak measurements, with a focus on the recent D0 and CDF combination of the forward-backward asymmetry of leptons from Z boson production and decay. I will also touch on the latest and ongoing measurements of the W boson mass and of the charge asymmetry in its leptonic decays.
This talk will cover the latest results of the ATLAS collaboration concerning Electroweak precision measurements.
We present an update of the global fit of the Standard Model electroweak sector to latest experimental results. We include new top quark and W boson mass measurements from the LHC, a measurement of the weak mixing angle from the Tevatron, and a new evaluation of the hadronic contribution to the electromagnetic coupling. The electroweak data combined with measurements of the Higgs boson coupling strengths and flavour physics observables are also used to constrain parameters of two-Higgs-doublet models. We discuss possible future directions of the electroweak fit, presenting fits to differential Higgs measurements at the High-Luminosity LHC in the context of an effective field theory.
Searches for the $ttH$ production in ATLAS with 36.1 $\mathrm{fb}^{-1}$ at $\sqrt{s}=13$ TeV in the $bb$, multilepton, $\gamma\gamma$ and $4l$ will be presented. The combined result provides evidence for the top Yukawa coupling.
The latest CMS measurements of the Higgs boson coupling to the top quark are presented. Different final states arising from Higgs boson decays to fermion and boson pairs are explored.
Results are presented from the ATLAS search for Standard Model Higgs bosons decaying to a $b\bar b$ or $c \bar c$ pair, produced in association with a $W$ or $Z$ boson. The analyzed data correspond to 36.1 fb$^-1$ of 13 TeV proton-proton collision data collected in Run 2 of the Large Hadron Collider. The combination of Run 1 and Run 2 data in the $b\bar b$ channel yields a ratio of the measured production rate to the SM prediction equal to $0.90 \pm 0.18 \text{(stat.)} ^{+0.21}_{-0.19} \text{(syst.)}$. The observed significance of $3.6\sigma$ provides evidence for the direct $Hbb$ Yukawa coupling. A similar search for $c \bar c$ decays results in an upper limit on the production cross section times branching ratio.
Summary of the newest rare and invible Higgs boson decays in CMS
The experimental status of di-Higgs searches from the ATLAS and CMS experiments will be presented.
The Belle-2 experiment is preparing itself for initial data collection in the upcoming months. The anticipated physics program is wide and diverse, ranging from dark photon searches to anomalies in precisions measurements of B meson decays. A brief overview of the Belle-2 experiment, detector and collider, and its current status will be presented.
Measurements of top production in the LHCb acceptance have particular sensitivity to high values of Bjorken-x, and offer complementary PDF constraints to measurements at the central detectors. In addition, the higher contribution from quark-initiated production to top pair production in the forward region leads to a larger expected charge asymmetry at LHCb than at the other experiments.
The latest results by the LHCb collaboration on top pair production will be discussed.
While Jarlskog-like flavor invariants are adequate for estimating CP-violation from closed fermion loops, non-invariant structures arise from rainbow-like processes.
For the CKM contributions to the quark EDM, or the PMNS contributions to lepton EDMs, the dominant diagrams have a rainbow topology whose flavor structure does not collapse to flavor invariants. Numerically, they are found typically much larger, and not necessarily correlated with, Jarlskog-like invariants.
The flavor structures in the quark and lepton sectors are systematically studied, assuming different mechanisms for generating neutrino masses.
In addition, the combined study of both Jarlskog-like and rainbow-like flavor structures shed new lights on the possible correlations between quark and lepton EDM.
The measurements of differential (in the fiducial phase space) and production mode cross sections are presented in the $H\rightarrow\gamma\gamma$ decay channel using $36~\text{fb}^{-1}$ data collected by the ATLAS detector at a centre of mass energy of $\sqrt{s}=13~\text{TeV}$. These characterise $pp\rightarrow H\rightarrow\gamma\gamma$ processes in a variety of ways; production mode cross sections directly test the compatibility of the data with the Standard Model (SM), whereas fiducial measurements make minimal SM assumptions and can thus be re-interpreted in order to constrain new physics models. The sensitivity is approximately double that of the $\sqrt{s}=8~\text{TeV}$ dataset. Finally, 5 differential distributions are used to constrain several Wilson coefficients using the effective field theory approach.
Search for H->aa with CMS data
We analyze the $ZH\eta$-vertex (where $\eta$ is a pseudoaxion), its dependence on high scale $f$, and the connection with custodial-violation, based on the effective field theory. As an example, we re-derive this vertex in the simplest little Higgs model. After canonically nomalization of the scalar kinetic part in the lagrangian, we find the exact Goldstone fields, and show that $ZH\eta$-vertex should appear at $\mathcal{O}(v^3/f^3)$ level. This result is quite different from those which have already existed in the literature for over ten years.
A search for new heavy quarks focusing on recent Vector-like quark searches with the ATLAS detector is presented.
I will discuss the interplay of precision measurements in low- and medium-energy facilities with high-energy searches at the LHC, using the Standard Model Effective Field Theory (SMEFT) as theoretical framework. Specific examples will be discussed, such as nuclear/atomic probes, LEP searches or flavor transitions. In each case, the synergy with LHC searches will be discussed.
We propose a minimal extension of the standard model which includes only one additional complex scalar field, flavon, with flavor-dependent global U(1) symmetry. It not only explains the hierarchical flavor structure in the quark and lepton sector (including neutrino sector), but also solves the strong CP problem by identifying the CP-odd component of the flavon as the QCD axion, which we call flaxion. Furthermore, the flaxion model solves the cosmological puzzles in the standard model, i.e., origin of dark matter, baryon asymmetry of the universe, and inflation. We show that the radial component of the flavon can play the role of inflaton without isocurvature nor domain wall problems. The dark matter abundance can be explained by the flaxion coherent oscillation, while the baryon asymmetry of the universe is generated through leptogenesis.
Natural models of Supersymmetry (SUSY) typically favor existence of light higgsinos. Models in which the only accessible SUSY particles are charginos and neutralinos that are predominantly higgsinos tend to have low mass splitting between these particles. Such models, commonly referred to as compressed models, lead to final states including low-momentum leptons and disappearing tracks that are experimentally challenging to characterize. This talk will present the latest results from Higgsino searches that are conducted taking advantage of the large pp collision dataset recorded by ATLAS in 2015 and 2016 at a centre-of-mass energy of 13 TeV.
We derive a new bound on diphoton resonances using inclusive diphoton cross section measurements at the LHC, in the so-far poorly constrained mass range between the Upsilon and the SM Higgs. This bound sets the current best limit on axion-like particles that couple to gluons and photons, for masses between 10 and 65 GeV. We also estimate indicative sensitivities of a dedicated diphoton LHC search in the same mass region, at 7, 8 and 14 TeV.
From strongly produced initial states, SUSY phenomenology offers a rich array of observable signatures. Naturalness arguments suggest decays of gluinos through heavy-flavor quarks. R-parity violation may offer signatures with many leptons or jets, but without or with only low missing transverse momentum. Several supersymmetric models also predict massive long-lived supersymmetric particles that may be detected through abnormal specific energy loss, appearing or disappearing tracks, displaced vertices, long time-of-flight or late calorimetric energy deposits. This talk discusses recent ATLAS results on the production of squarks and gluinos focusing on the non-vanilla scenarios.
I will briefly overview the potential of LHCb in direct searches for new particles beyond the SM and comment on the latest results.
In the framework of the Electroweak Chiral Lagrangian, we analyze and make predictions of the phenomenology associated to Vector Boson Scattering at the LHC in the process $pp\to W^+Zjj$ and in the case of the appearance of a vector resonance. This resonance is dynamically generated by the unitarization of the scattering amplitudes with the Inverse Amplitude Method, well known in the context of pion physics. Through this study, we are able to comment on the LHC sensitivity to some parameters of the EChL.
This presentation covers a search for the associated production of the Higgs boson with a top quark pair ($t\bar{t}H$). The search is performed in multileptonic final states using a dataset corresponding to an integrated luminosity of 36.1 fb$^{−1}$ of proton-proton collision data recorded by the ATLAS experiment at a center-of-mass energy of $\sqrt{s} =$ 13 TeV at the Large Hadron Collider. Higgs boson decays to $WW^*$, $\tau\tau$ and $ZZ^*$ are targeted. Seven final states, categorized by the number and flavor of charged-lepton candidates, are examined for the presence of the Standard Model Higgs boson with a mass of 125 GeV and a pair of top quarks. An excess of events over the expected background from Standard Model processes is found with an observed significance of 4.1 standard deviations, compared to an expectation of 2.8 standard deviations. New analysis techniques to suppress the main backgrounds are presented. Further the combination of this result with other $t\bar{t}H$ searches from the ATLAS experiment using the Higgs boson decay modes to $b\bar{b}$, $\gamma\gamma$ and $ZZ^*\rightarrow4\ell$ is briefly reported.
We will talk about simplified MSSM models for light neutralinos and charginos with realistic
mass spectra and realistic gaugino-higgsino mixing, that can be used in experimental searches
at the LHC. The formerly used naive approach of defining mass spectra and mixing matrix elements
manually and independently of each other does not yield genuine MSSM benchmarks. Therefore,
we suggest the use of models, whose mass spectra and mixing matrix elements are the result of
a proper matrix diagonalisation. We scan over only the four relevant parameters $\{\mu, \tan \beta,
M_{1}, M_{2}\}$ for a grid of neutralino and chargino masses, having defined a measure for the quality of
the fit, that can also include criteria such as a maximal gaugino or higgsino content.
The XENON collaboration is seeking to directly measure weakly interacting massive particles (WIMPs) using liquid xenon time projection chambers (TPCs) of increasing target mass. The current stage, XENON1T, utilizes 3.2 tons of ultra-pure liquid xenon and has collected more than 1 ton x year of exposure. This dataset allows unprecedented sensitivity on the WIMP-nucleon cross section and new results from this dataset will be announced in spring 2018. A new upgrade, XENONnT, is under construction and will further increase the target mass by a factor of 3 compared to XENON1T. This detector will start operation at the end of 2019.
This talk focuses on the pending result and the analysis of the XENON1T science data.
DarkSide uses a dual-phase Liquid Argon Time Projection Chambers to search for WIMP dark matter. The talk will present the latest result from the current experiment, DarkSide-50, running since mid 2015 a 50-kg-active-mass TPC, filled with argon from an underground source. The next stage of the Darkside program will be a new generation experiment involving a global collaboration from all the current Argon based experiments.
I will provide a unified presentation of extensions of the Minimal Dark Matter framework in which new fermionic electroweak multiplets are coupled to each other via the Standard Model Higgs doublet. I will discuss an estimate the parameter space for viable dark matter candidates including an estimate for the Sommerfeld effect. I will also argue how the coupling to the Higgs can bring the Minimal Dark Matter scenario within the reach of present and future direct detection experiments.
A review of the recent results obtained by the ATLAS Collaboration in the search for Dark Matter signatures in events with an high-pt Standard Model object recoiling against MET.
A short summary of the theoretical framework for DM searches at colliders is included.
The origin and nature of the dark matter in the Universe is one of the most pressing questions in fundamental physics. However, despite the enormous experimental effort no conclusive hint for a weakly interacting massive particle (WIMP) has been found, putting pressure on the widely considered WIMP dark matter explanation. In this talk we examine new avenues beyond the standard WIMP picture. We show that scrutinizing the well-known co-annihilation scenario and dropping the commonly made assumption of chemical equilibrium between co-annihilating partners offers new phenomenological possibilities. By solving the full coupled set of Boltzmann equations we find solutions that accommodate the measured dark matter density while requiring very small couplings that are in accordance with current null-results in WIMP searches. Despite the very weak coupling the dark matter abundance is largely insensitive to the cosmological history prior to freeze-out in contrast to other scenarios like freeze-in or superWIMPs. We discuss current constraints and motivate future searches at the LHC.
Low-mass bosonic dark matter particles produced after the Big Bang may form an oscillating classical field, which can be sought for in a variety of low-energy laboratory experiments based on spectroscopic, interferometric and magnetometric techniques, as well as in astrophysical phenomena. Dark bosons can also mediate anomalous fifth forces between ordinary-matter particles. Recent measurements in atoms and astrophysical phenomena have already allowed us to improve on existing constraints on a broad range of non-gravitational interactions between dark bosons and ordinary-matter particles by many orders of magnitude (up to 15 orders of magnitude in the case of low-mass dark matter). Additionally, existing atomic and nuclear spectroscopy data have allowed us to improve limits on long-range neutrino-mediated forces by 18 orders of magnitude.
References
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[3] B. M. Roberts, Y. V. Stadnik, V. A. Dzuba, V. V. Flambaum, N. Leefer, D. Budker, Phys. Rev. D 90, 096005 (2014).
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[7] Y. V. Stadnik, V. V. Flambaum, Phys. Rev. A 93, 063630 (2016).
[8] Y. V. Stadnik, V. V. Flambaum, Phys. Rev. A 94, 022111 (2016).
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[10] C. Abel et al. (nEDM collaboration), Phys. Rev. X 7, 041034 (2017).
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NEWS-G (New Experiments With Spheres-Gas) is an innovative experiment aiming to shine a light on the dark matter conundrum using a novel gaseous detector, the Spherical Proportional Counter. It uses light noble gases, such as Hydrogen, Helium, and Neon, as targets, to search for Weakly Interacting Massive Particles (WIMPs) down to the sub-GeV/c${}^{2}$ mass region. The first detector of NEWS-G (SEDINE), is a 60 cm diameter sphere already operated in the Underground Laboratory of Modane (France), while the full-scale detector, with 140 cm diameter, will be installed in SNOLab (Canada) at the end of this year. In this talk, I will present the first NEWS-G results with Neon as target nuclei, which exclude at 90% confidence level (C.L.) cross-sections above $4.4\cdot {10}^{37}$ cm${}^{2}$ for a 0.5 GeV/c$^{2}$ WIMP based on 9.7 kg$\cdot$days of exposure, and I will discuss the status of the project and prospects for the future.
Extra dimensions (ED) can provide a useful tool for model-building. In this paper we introduce a single, flat ED extension of the kinetic-mixing/dark photon (DP) portal for dark matter (DM)
interactions with the Standard Model (SM) assuming a compactification `radius' of order $R^{-1}\sim10-1000$ MeV and examine the resulting modifications to and augmentation of the
usual DP phenomenology. In the present scenario, both the DP and DM experience the full 5-D while the SM fields are constrained to lie on a 4-D brane at the boundary of the ED. Such a
setup can naturally yield the observed value of the DM relic density and explain the required rough degeneracy of the DM and DP masses needed to obtain it. Gauge symmetry breaking can
occur via boundary conditions without the introduction of an additional singlet Higgs scalar thus avoiding all constraints associated with the coupling of such a field to the usual SM Higgs
field in 5-D. The self-consistency of the field redefinitions that map the gauge fields into a canonical basis and thus removing the kinetic mixing terms is found to lead to a strong model building
constraint on the ED setup involving a brane localized kinetic term for the 5-D gauge field on the SM brane. Multiple variations of this scenario are found to be possible which are consistent with
all current experimental constraints but which predict very different phenomenologies. In this paper, after setting up the general model formalism, we discuss in detail the case of a complex
scalar 5-D DM field, consistent with constraints arising from the CMB, which may or may not obtain a vacuum expectation value (vev). The resulting Kaluza-Klein (KK) towers of both the DM
and DP fields are found to yield interesting and distinctive signatures while simultaneously being constrained by a wide array of existing measurements but with the details being dependent
upon the specifics of the KK spectrum and the presence or absence of this 5-D scalar vev.
The QCD axion is a natural consequence to the Peccei-Quinn solution to the Strong-CP problem and also happens to be a natural dark matter candidate. The first run of the Gen 2 campaign with the Axion Dark Matter Experiment (ADMX) has searched for QCD axions with mass in the few ueV range with unprecedented sensitivity. This talk will discuss how cryogenic operating conditions with ultra-low-noise RF SQID amplifiers enabled this achievement and how they will be used as the search mass is increased.
Mr. N. J. Ayres on behalf of the PSI nEDM Collaboration
Axions and axion-like particles (ALPs) are popular dark matter candidates. Ultralight axion and ALP cold dark matter could manifest as a classical-like field, oscillating coherently on a galactic scale. Through their couplings to gluons, this field would induce an oscillation in the measured value of the electric dipole moments of neutrons and other particles. We analyse datasets from the Sussex-RAL-ILL nEDM experiment and the current nEDM experiment at the Paul Scherrer Institute (2015-2016) to obtain limits on a potential oscillation in the value of the EDM.
While many experiments probe the axion-photon coupling, we set the first laboratory limits on the axion-gluon coupling, improving upon the previous indirect cosmological limits by up to 3 orders of magnitude. Additionally, we improve upon laboratory constraints on the axion coupling to nucleons by up to a factor of 40.
Paper: Phys. Rev. X 7, 041034 (2017)- Search for Axionlike Dark Matter through Nuclear Spin Precession in Electric and Magnetic Fields
Kinetic decoupling of dark matter (DM) typically happens much later than chemical freeze-out. In fact, local thermal equilibrium is an important assumption for the usual relic density calculations based on solving the Boltzmann equation [for its 0-th moment] describing the DM number density. But is this assumption always justified? In this talk I will address this question and discuss the consequences of more accurate treatments, one relying on the inclusion of higher moments of the Boltzmann equation and the second on solving the evolution of the phase space distribution function fully numerically. I will show explicit examples where such a more accurate treatment is necessary. One of these is the Scalar Singlet model, often referred to as the simplest WIMP DM possibility from a model-building perspective.
We explore the possibility that Dark Matter is the lightest hadron made of two stable color octet Dirac fermions $Q$. The cosmological DM abundance is reproduced for $M_Q\approx 9.5$ TeV, compatibly with direct, indirect and collider searches. Hybrid hadrons, made of $Q$ and of SM quarks and gluons, have large QCD cross sections, and do not reach underground detectors. Their cosmological abundance is $10^5$ times smaller than DM, such that their unusual signals seem compatible with bounds.
The observation is presented of the Z boson rare decay to a ψ meson and two oppositely charged same-flavor leptons, l+l−, where ψ represents the sum of J/ψ and ψ(2S) → J/ψ X, and l = μ, e, is presented. The data sample of proton-proton collisions at a center-of-mass energy of 13 TeV corresponds to an integrated luminosity of 35.9fb−1 accumulated by the CMS experiment at the CERN LHC. The signal is observed with a significance in excess of 5 standard deviations. Removing contributions from ψ(2S) decays to J/ψ, the signal is interpreted as being entirely from Z → J/ψ l+l−, with its fiducial branching fraction relative to that of the decay Z → μ+μ−μ+μ− measured to be
B(Z → J/ψ l+l−)/B(Z → μ+μ−μ+μ−) = 0.70 ± 0.18 (stat) ± 0.05 (syst)
This result is obtained with the assumption of no J/ψ polarization. Extreme polarization scenarios give a variation of the fiducial branching fraction measurement of (−22 to +24)%.
A search for a new heavy particle decaying to a pair of vector bosons (WW or WZ) is presented using data from the CMS detector corresponding to an integrated luminosity of 35.9/fb collected in proton-proton collisions at a centre-of-mass energy of 13 TeV in 2016. One of the bosons is required to be a W boson decaying to eν or μν, while the other boson is required to be reconstructed as a single massive jet with substructure compatible with that of a highly-energetic quark pair from a W or Z boson decay. The search is performed in the resonance mass range between 1.0 and 4.5 TeV. The largest deviation from the background-only hypothesis is observed for a mass near 1.4 TeV and corresponds to a local significance of 2.5 standard deviations. The result is interpreted as an upper bound on the resonance production cross section. Comparing the excluded cross section values and the expectations from theoretical calculations in the bulk graviton and heavy vector triplet models, spin-2 WW resonances with mass smaller than 1.07 TeV and spin-1 WZ resonances lighter than 3.05 TeV, respectively, are excluded at 95% confidence level.
In the framework of the (B−L) Supersymmetric Standard Model (BLSSM), we assess the ability of ground and space based experiments to establish the nature of its prevalent Dark Matter (DM) candidate, the sneutrino, which could either be CP-even or -odd. Firstly, by benchmarking this theory construct against the results obtained by the Planck spacecraft, we extract the portions of the BLSSM parameter space compliant with relic density data. Secondly, we show that, based on current sensitivities of the Fermi Large Area Telescope (FermiLAT) and their future projections, the study of high-energy γ-ray spectra will eventually enable us to extract evidence of this DM candidate through its annihilations into W+W− pairs (in turn emitting photons), in the form of both an integrated flux and a differential energy spectrum which cannot be reconciled with the assumption of DM being fermionic (like, e.g., a neutralino), although it should not be possible to distinguish between the scalar and pseudoscalar hypotheses. Thirdly, we show that, while underground direct detection experiments will have little scope in testing sneutrino DM, the Large Hadron Collider (LHC) may be able to do so in a variety of multi-lepton signatures, with and without accompanying jets (plus missing transverse energy), following data collection during Run 2 and 3.
The cosmic-ray flux of antiprotons is measured with unprecedented accuracy by the space-borne particle spectrometers AMS-02. Its interpretation requires correct description of the dominant production process for antiprotons in our Galaxy, namely, the interaction of cosmic-ray proton and helium with the interstellar medium. In the light of new cross section measurements by the NA61 experiment of $p + p \rightarrow \bar{p} + X$ and the first ever measurement of $p + \mathrm{He} \rightarrow \bar{p} + X$ by the LHCb experiment, we update the parametrization of proton-proton and proton-nucleon cross sections.
We find that the LHCb $p$He data constrain a shape for the cross section at high energies and show for the first time how well the rescaling from the $pp$ channel applies to a helium target. By using $pp$, $p$He and $p$C data we estimate the uncertainty on the Lorentz invariant cross section for all relevant antiproton production channels in the Galaxy. We use these new cross sections to compute the antiproton source terms. The uncertainties on the total source term is at the level of $\pm20$\% and slightly increase below antiproton energies of 5~GeV. Since this exceeds the uncertainties on the antiproton flux which is measured by AMS-02 at an accuracy of 5\% in an energy range from 1 to 400~GeV, we finally quantify the necessity of new data on antiproton production cross sections, and pin down the kinematic parameter space which should be covered by future data. Our results are discussed both in the center-of-mass reference frame, suitable for collider experiments, and in the laboratory frame, as occurring in the Galaxy. We find that cross section data should be collected with accuracy better that few percent with proton beams from 10 GeV to 6 TeV and a pseudorapidity $\eta$ ranging from 2 to almost 8 or, alternatively,with $p_T$ from 0.04 to 2 GeV and $x_R$ from 0.02 to 0.7.
Thank to the stable operation of the J-PARC proton accelerator at the power of 470-475kW, T2K neutrino data was almost doubled in one year and a total exposure of $2.65\times10^{21}$ POT has been collected by the end of 2017. Along with this achievement, T2K has improved substantially the oscillation analyses by introducing a new selection, adding a new signal sample and understanding better the neutrino-nucleus interactions. All of these efforts result in more precise measurement of neutrino oscillation parameters and T2K firstly excludes the CP-conserving values of at 2$\sigma$. To intensively explore CP violation in the lepton sector and continue to produce high-impact results, T2K proposes a program extension, T2K-II, to collect $20\times 10^{21}$ POT and ND280 upgrade is also planned to resolve uncertainties from neutrino-nucleus interaction modeling. Physics prospects of T2K-II and ND280 upgrade are sensational and T2K welcomes new collaborators for these developments.
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We report the first measurement of monoenergetic muon neutrino charged current interactions. MiniBooNE has isolated 236 MeV muon neutrino events originating from charged kaon decay at rest ($K^+ → μ+ν_μ$) at the NuMI beamline absorber. These signal $ν_μ$-carbon events are distinguished from primarily pion decay in flight $ν_μ$ and $\overline{ν}_μ$ backgrounds produced at the target station and decay pipe using their arrival time and reconstructed muon energy. The significance of the signal observation is at the 3.9σ level. The muon kinetic energy, neutrino-nucleus energy transfer (ω = $E_ν − E_μ$), and total cross section for these events is extracted. This result is the first known-energy, weak- interaction-only probe of the nucleus to yield a measurement of ω using neutrinos, a quantity thus far only accessible through electron scattering.
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The sensitivity of beam dump experiments to heavy neutral leptons depends on the relative strength of their couplings to individual lepton flavours in the Standard Model. We study the impact of present neutrino oscillation data on these couplings in the minimal type I seesaw model and find that it significantly constrains the allowed heavy neutrino flavour mixing patterns. We estimate the effect that the DUNE experiment will have on these predictions. We then discuss implication that this has for the sensitivity of the NA62 experiment when operated in the beam dump mode and provide sensitivity estimates for different benchmark scenarios. We find that the sensitivity can vary by almost two orders of magnitude for general choices of the model parameters, but depends only weakly on the flavour mixing pattern within the parameter range that is preferred by neutrino oscillation data.
Majorana vs. Dirac and neutrino decays
The EXO-200 experiment consists of a time projection chamber filled with ~150 kg of liquid xenon enriched at 80.7% of the 136Xe isotope. The low background level reached within the detector made possible the detection of the two neutrinos double decay of 136Xe, set the most precise measurement of a double beta decay half life to date and provided one of the most sensitive search for the neutrinoless double beta decay. After a brief hiatus in operations, the experiment restarted data taking with upgrades to its front-end electronics and a Rn suppression system. This presentation will cover the recent results of the EXO-200 collaboration published last year, which include the first two years of data with the detector in its first phase and one year of data taken with the upgraded detector.
First Results from the CUORE experiment on the search for neutrinoless double beta decay of Te-130.
CUPID-0 is the first large array of enriched scintillating ZnSe cryogenic calorimeters implementing active particle identification. The detector consists of an array of 24 ZnSe crystals 95% enriched in $^{82}$Se and two natural ZnSe crystals for a total mass of 10.5 kg installed in a dilution refrigerator located underground in the Laboratori Nazionali del Gran Sasso.
We will report the first result of the search for neutrinoless double beta decay (0$\nu$DBD) in $^{82}$Se based on the data collected between june and november 2017. We find no evidence in a 3.45 kg yr exposure and we set the most stringent lower limit on the 0νDBD $^{82}$Se half life of $T_{0\nu}^{1/2}$ >2.4×10$^{24}$ yr (90% C.I.) which corresponds to an effective Majorana neutrino mass m$_{\beta\beta}$ < (376-770) meV. This excellent result was obtained also thanks to the heat-light readout that provides a unique tool for $\alpha$ particle discrimination and allows to suppress the background in the region of interest to an unprecedented level for a bolometric experiment.
The smallness of neutrino masses provides a tantalizing allusion to physics beyond the standard model (SM). Heavy neutral leptons (HNL), such as hypothetical sterile neutrinos, accommodate a way to explain this observation, through the see-saw mechanism. If they exist, HNL could also provide answers about the dark matter nature, and baryon asymmetry of the universe. A search for the production of HNL at the LHC, originating from leptonic W boson decays through the mixing of the HNL with SM neutrinos, is presented. The search focuses on signatures with three leptons, providing a clean signal for probing the production of the HNL in a wide mass range never explored before at the LHC: down to 1 GeV, and up to 1.2 TeV. The sample of pp collisions collected by the CMS detector throughout 2016 is used, amounting to a volume of 35.9/fb. Separated into two parts, the search is respectively optimized for finding HNL of masses above and below that of the W boson. The final results are presented in the plane of the mixing parameter of HNL to their SM counterparts, versus their mass, and are the first such result at a hadron collider for masses below 40 GeV and the first direct result for masses above 500 GeV.
Heavy neutrinos with masses below the electroweak scale can simultaneously
generate the light neutrino masses via the seesaw mechanism and the baryon asymmetry of the universe via leptogenesis.
The requirement to explain these phenomena imposes constraints on the mass spectrum of the heavy neutrinos, their flavor mixing pattern and their CP properties.
We combine bounds from different experiments in the past to map the viable parameter regions in which the minimal low scale seesaw model can explain the observed neutrino oscillations, while being consistent with the negative results of past searches for physics beyond the Standard Model.
We then study which additional predictions for the properties of the heavy neutrinos can be made based on the requirement to explain the observed baryon asymmetry of the universe.
If any heavy neutral leptons are discovered in the future, our results can be used to assess whether these particles are indeed the common origin of the light neutrino masses and the baryon asymmetry of the universe.
In this talk, I will show how the cosmological and astrophysical implications of a dark matter-neutrino coupling allow us to exclude a large region of the parameter space for different simplified dark matter models.
CUPID-Mo is a bolometric demonstrator experiment searching for neutrinoless double decay (0$\nu$2$\beta$) of $^{100}$Mo. The observation of this process, which is not allowed by the Standard Model, would determine the Majorana nature of neutrino and its mass scale. The CUPID-Mo detector array consists of 20 scintillating bolometers made of Li$_2^{100}$MoO$_4$ crystals (2.34 kg of $^{100}$Mo), assembled in a compact structure of 5 suspended towers. Data taking is ongoing in the EDELWEISS cryostat at the Underground Laboratory of Modane (LSM, France). The main goal of the CUPID-Mo experiment is to demonstrate "zero-background" conditions in the region of the expected 0$\nu$2$\beta$ decay peak of $^{100}$Mo with six months of measurement. The reproducibility of Li$_2^{100}$MoO$_4$ scintillating bolometers with high performance should be confirmed, demonstrating the applicability of the CUPID-Mo technology for the future ton-scale 0$\nu$2$\beta$ decay bolometric experiment CUPID.
</body> </html>We propose a model in which the pattern of the mass matrix for the inverse seesaw originates from a dynamical breaking of a global B-L symmetry.
The smallness of the off-diagonal parameters in the mass matrix is hence explained in a natural way by the symmetry-breaking vacuum expectation value of a scalar field.
To ensure an anomaly free theory we introduce additional degrees of freedom whose interesting phenomenology we will discuss in this talk.
Heavy neutrino states can be up-scattered from neutral-current interactions between neutrinos and nuclei in several new physics models. If the incoming neutrino is energetic enough, the heavy neutrino may travel some distance before decaying. In this talk, we consider the tau neutrinos created by the flavor oscillation of the atmospheric muon neutrino flux as a source of such events. At IceCube, this would lead to a “double-bang” (DB) event topology, similar to what is predicted to occur for tau neutrinos at ultra-high energies. The DB event topology has an extremely low background rate from coincident atmospheric cascades, making this a distinctive signature of new physics. The results indicate that IceCube should already be able to derive new competitive constraints on the mixing between tau neutrinos and GeV-scale sterile neutrinos using existing data.
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The structure of the earth interior and in particular the earth's core is still a big puzzle. Propagation of seismic waves allow us to infer properties of the mantle and the superficial layers, but the core and the inner core remain almost unmeasured directly. In this talk I will show the first sensitive neutrino earth tomography result using one year of IceCube atmospheric neutrinos data.
Heavy neutral leptons, such as massive sterile neutrinos, are introduced in many beyond the Standard Model theories. Our aim is to study the potential of the LHC to produce and discover this kind of new particles. Moreover, and depending on their masses and couplings, they can be long-lived and lead to signatures with displaced vertices.
Comparison with dedicated efforts (SHiP, FCC-ee)
The simplest extension of the SM that can account for neutrino masses consists in the addition of 2 right-handed neutrinos to the SM field content. In addition to the generation of the light neutrino mass and mixing pattern measured in neutrino oscillations, the low scale realization of the model provides an explanation for the matter-antimatter asymmetry of the Universe via ARS leptogenesis, with right-handed neutrino masses in the range [0.1-100] GeV. The heavy states can thus be produced and searched for in neutrinoless double beta decay searches, beam dump experiments, as SHiP or DUNE, and collider experiments as FCC-ee. I will show that for O(GeV) scale right-handed neutrinos, future experimental data can provide sufficient information to predict the matter asymmetry of the universe. Furthermore, the flavor structure of the minimal model is extremely constrained and shows a very interesting correlation with the PMNS CP-phases which opens a new window for leptonic CP violation.
Daya Bay reactor neutrino experiment has been taking data since the year of 2012 with eight antineutrino detectors deployed at three underground experimental halls at distances of ~400 m - 2000 m away from the six 2.9 GWth nuclear reactors. With millions of inverse beta decay candidate events and well controlled systematics, Daya Bay has measured the neutrino mixing angle theta13 at 4% precision level. The measured reactor antineutrino flux is consistent with the previous experimental results, ~6% lower than the Huber-Mueller model prediction. Meanwhile, the measured spectrum also deviates from the model prediction at ~3σ confidence level. The isotope U235, with unequal deficit compared with isotope Pu239, is likely to be the primary cause of the so-called “reactor antineutrino anomaly” based on the reactor fuel evolution data.
The observed antineutrino flux from nuclear reactors is consistently lower than predicted. This anomaly could hint at oscillations of active neutrinos into a new sterile neutrino species, or it could simply be a reflection of underestimated systematic uncertainties in the theoretical flux prediction. We review the status of both hypothesis in view of recent developments. In particular, we scrutinize recent Daya Bay results, which aim to determine whether the deficit depends on the isotope from which neutrinos are produced (as would be likely if the problem is with the flux prediction), or is independent thereof (as would be expected if the sterile neutrino hypothesis is true). We also comment on new short-baseline data, and we discuss reactor data in the context of a global fit.
Brief overview of the sterile neutrino searches at reactors and release of the first results of the STEREO experiment.
Cosmological observations represent a powerful tool to constrain neutrino physics, complementary to laboratory experiments. In particular, observations of the cosmic microwave background (CMB) have the potential to constrain the properties of relic neutrinos, as well as of additional light relic particles in the Universe. I will present current constraints on neutrino properties, including their mass and effective number, from the most recent Planck data, possibly in combination with other cosmological probes, especially galaxy surveys. I will also briefly discuss prospects from future experiments, both from the ground and from space.
Ultrahigh energy cosmic rays are the most energetic particles observed,
reaching orders of magnitude above the LHC energy range.
The Pierre Auger Observatory, located in Mendoza province, Argentina
is the largest Ultrahigh energy cosmic ray observatory in the world.
Since the start of operation in 2004 the Observatory has reached
unprecedented exposure and the high-quality data set spans three orders of
magnitude in energy, yielding a plethora of scientific findings.
A selection of recently published results on the large and intermediate scale
anisotropies in Ultrahigh energy cosmic ray arrival directions
and search for neutrinos correlated with GW170817 will be presented in
this contribution.
DAMPE Mission and Its First Results
I will give a critical point of view on the theories trying to explain the DAMPE "excesses".
The discovery of gravitational waves produced by the coalescence of 10 solar mass black holes revived the possibility that the mysterious dark matter of the Universe might consist of primordial black holes (PBHs). I review the present constraints on the PBH abundance, discuss PBH production by single field inflation and present the predictions for the gravitational wave signals in this scenario. The talk is based on the following papers arXiv:1705.05567, arXiv:1705.06225, arXiv:1707.01480 and on the work in progress.
