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Conference paperFujii Y, 2024,
Charged Lepton Flavour Violation: experimental activities
Charged lepton flavour violation processes are powerful probes to investigate new physics beyond the standard model of particle physics. There are several ongoing activities and future projects. All of them are going to achieve the levels of sensitivity which are able to explore many new physics scenarios, corresponding to higher energy scale than that is directly accessible with present particle colliders. This paper introduces the recent and present experimental efforts in this area of searches, especially focusing on MEG, MEG2, Mu3e, Mu2e and COMET.
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Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Amplitude Analysis of the <i>B</i><SUP>0</SUP> - <i>K</i>*<SUP>0</SUP> μ<SUP>+</SUP>μ<SUP>-</SUP> Decay
, PHYSICAL REVIEW LETTERS, Vol: 132, ISSN: 0031-9007 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Observation of WWγ Production and Search for Hγ Production in Proton-Proton Collisions at √ s=13 TeV
, PHYSICAL REVIEW LETTERS, Vol: 132, ISSN: 0031-9007 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for long-lived heavy neutral leptons with lepton flavour conserving or violating decays to a jet and a charged lepton
, Journal of High Energy Physics, Vol: 2024<jats:title>A<jats:sc>bstract</jats:sc> </jats:title><jats:p>A search for long-lived heavy neutral leptons (HNLs) is presented, which considers the hadronic final state and coupling scenarios involving all three lepton generations in the 2–20 GeV HNL mass range for the first time. Events comprising two leptons (electrons or muons) and jets are analyzed in a data sample of proton-proton collisions, recorded with the CMS experiment at the CERN LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 138 fb<jats:sup><jats:italic>−</jats:italic>1</jats:sup>. A novel jet tagger, based on a deep neural network, has been developed to identify jets from an HNL decay using various features of the jet and its constituent particles. The network output can be used as a powerful discriminating tool to probe a broad range of HNL lifetimes and masses. Contributions from background processes are determined from data. No excess of events in data over the expected background is observed. Upper limits on the HNL production cross section are derived as functions of the HNL mass and the three coupling strengths <jats:italic>V</jats:italic><jats:sub><jats:italic>ℓ</jats:italic>N</jats:sub> to each lepton generation <jats:italic>ℓ</jats:italic> and presented as exclusion limits in the coupling-mass plane, as lower limits on the HNL lifetime, and on the HNL mass. In this search, the most stringent limit on the coupling strength is obtained for pure muon coupling scenarios; values of <jats:italic>|</jats:italic><jats:inline-formula><jats:alternatives><jats:tex-math>$$ {V}_{\mu \textrm{N}}^2 $$</jats:tex-math><mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>V</mml:mi> <mml:m
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
New Structures in the J=ψJ=ψ Mass Spectrum in Proton-Proton Collisions at √ s=13 TeV
, PHYSICAL REVIEW LETTERS, Vol: 132, ISSN: 0031-9007 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Measurement of <i>J</i>/ψ-pair production in <i>pp</i> collisions at √<i>s</i>=13 TeV and study of gluon transverse-momentum dependent PDFs
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Observation of Ξ<sub>b</sub><SUP>0</SUP>→ Ξ<sub>c</sub> <SUP>+</SUP> D<sub>s</sub><SUP>-</SUP> and Ξ<sub>b</sub><SUP>0</SUP> c D- s decays
, EUROPEAN PHYSICAL JOURNAL C, Vol: 84, ISSN: 1434-6044 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for dark matter particles in W<sup>+</sup>W<sup>−</sup> events with transverse momentum imbalance in proton-proton collisions at s = 13 TeV
, Journal of High Energy Physics, Vol: 2024A search for dark matter particles is performed using events with a pair of W bosons and large missing transverse momentum. Candidate events are selected by requiring one or two leptons (ℓ = electrons or muons). The analysis is based on proton-proton collision data collected at a center-of-mass energy of 13 TeV by the CMS experiment at the LHC and corresponding to an integrated luminosity of 138 fb−1. No significant excess over the expected standard model background is observed in the ℓνqq and 2ℓ2ν final states of the W+W− boson pair. Limits are set on dark matter production in the context of a simplified dark Higgs model, with a dark Higgs boson mass above the W+W− mass threshold. The dark matter phase space is probed in the mass range 100–300 GeV, extending the scope of previous searches. Current exclusion limits are improved in the range of dark Higgs masses from 160 to 250 GeV, for a dark matter mass of 200 GeV.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Determination of short- and long-distance contributions in B0 →k∗0μ+μ- decays
, Physical Review D, Vol: 109, ISSN: 2470-0010An amplitude analysis of the B0→K∗0μ+μ- decay is presented. The analysis is based on data collected by the LHCb experiment from proton-proton collisions at s=7, 8 and 13 TeV, corresponding to an integrated luminosity of 4.7 fb-1. For the first time, Wilson coefficients and nonlocal hadronic contributions are accessed directly from the unbinned data, where the latter are parametrized as a function of q2 with a polynomial expansion. Wilson coefficients and nonlocal hadronic parameters are determined under two alternative hypotheses: the first relies on experimental information alone, while the second one includes information from theoretical predictions for the nonlocal contributions. Both models obtain similar results for the parameters of interest. The overall level of compatibility with the Standard Model is evaluated to be between 1.8 and 1.9 standard deviations when looking at the C9 Wilson coefficient alone, and between 1.3 and 1.4 standard deviations when considering the full set of C9,C10,C9′ and C10′ Wilson coefficients. The ranges reflect the theoretical assumptions made in the analysis.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2024,
Study of azimuthal anisotropy of γ(1S) mesons in pPb collisions at √S<sub>NN</sub>=8.16 TeV
, PHYSICS LETTERS B, Vol: 850, ISSN: 0370-2693 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for new Higgs bosons via same-sign top quark pair production in association with a jet in proton-proton collisions at √s=13 TeV
, PHYSICS LETTERS B, Vol: 850, ISSN: 0370-2693 -
Journal articlePasatembou E, Baynham CFA, Buchmuller O, et al., 2024,
Progress toward ultra-cold Sr for the AION project-A red MOT and an optical-heterodyne diagnostic tool for injection-locked laser diodes
, AVS QUANTUM SCIENCE, Vol: 6 -
Journal articleStray B, Ennis O, Hedges S, et al., 2024,
Centralized design and production of the ultra-high vacuum and laser-stabilization systems for the AION ultra-cold strontium laboratories
, AVS Quantum Science, Vol: 6, ISSN: 2639-0213This paper outlines the centralized design and production of the ultra-high-vacuum sidearm and laser-stabilization systems for the AION Ultra-Cold Strontium Laboratories. Commissioning data on the residual gas and steady-state pressures in the sidearm chambers, on magnetic field quality, on laser stabilization, and on the loading rate for the 3D magneto-optical trap are presented. Streamlining the design and production of the sidearm and laser stabilization systems enabled the AION Collaboration to build and equip in parallel five state-of-the-art Ultra-Cold Strontium Laboratories within 24 months by leveraging key expertise in the collaboration. This approach could serve as a model for the development and construction of other cold atom experiments, such as atomic clock experiments and neutral atom quantum computing systems, by establishing dedicated design and production units at national laboratories.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2024,
Measurements of azimuthal anisotropy of nonprompt D<SUP>0</SUP> mesons in PbPb collisions at √s<sub>NN</sub>=5.02 TeV
, PHYSICS LETTERS B, Vol: 850, ISSN: 0370-2693 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Curvature-bias corrections using a pseudomass method
, JOURNAL OF INSTRUMENTATION, Vol: 19, ISSN: 1748-0221 -
Journal articleQue Z, Fan H, Loo M, et al., 2024,
LL-GNN: Low Latency Graph Neural Networks on FPGAs for High Energy Physics
, ACM TRANSACTIONS ON EMBEDDED COMPUTING SYSTEMS, Vol: 23, ISSN: 1539-9087 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Measurement of the CKM angle γ in the B<SUP>0</SUP>→DK <SUP>*0</SUP> channel using self-conjugate D→ K<sub>S</sub><SUP>0</SUP>h<SUP>+</SUP> h<SUP>-</SUP> decays
, EUROPEAN PHYSICAL JOURNAL C, Vol: 84, ISSN: 1434-6044 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Observation of Cabibbo-Suppressed Two-Body Hadronic Decays and Precision Mass Measurement of the Ω<SUP>0</SUP><sub>c </sub>Baryon
, PHYSICAL REVIEW LETTERS, Vol: 132, ISSN: 0031-9007 -
Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Enhanced Production of Λ_{b}^{0} Baryons in High-Multiplicity pp Collisions at sqrt[s]=13 TeV.
, Phys Rev Lett, Vol: 132The production rate of Λ_{b}^{0} baryons relative to B^{0} mesons in pp collisions at a center-of-mass energy sqrt[s]=13 TeV is measured by the LHCb experiment. The ratio of Λ_{b}^{0} to B^{0} production cross sections shows a significant dependence on both the transverse momentum and the measured charged-particle multiplicity. At low multiplicity, the ratio measured at LHCb is consistent with the value measured in e^{+}e^{-} collisions, and increases by a factor of ∼2 with increasing multiplicity. At relatively low transverse momentum, the ratio of Λ_{b}^{0} to B^{0} cross sections is higher than what is measured in e^{+}e^{-} collisions, but converges with the e^{+}e^{-} ratio as the momentum increases. These results imply that the evolution of heavy b quarks into final-state hadrons is influenced by the density of the hadronic environment produced in the collision. Comparisons with several models and implications for the mechanisms enforcing quark confinement are discussed.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2024,
Two-particle Bose-Einstein correlations and their Lévy parameters in PbPb collisions at<i> √sNN</i>=5.02 TeV
, PHYSICAL REVIEW C, Vol: 109, ISSN: 2469-9985 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Study of <i>B<sub>c</sub></i><SUP>+</SUP> → χ<i><sub>c</sub></i> π<SUP>+</SUP> decays
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleArmano M, Audley H, Baird J, et al., 2024,
Sensor noise in<i> LISA</i><i> Pathfinder:</i> Laser frequency noise and its coupling to the optical test mass readout
, PHYSICAL REVIEW D, Vol: 109, ISSN: 2470-0010 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
A model-independent measurement of the CKM angle γ in partially reconstructed B<SUP>±</SUP>→D<SUP>∗</SUP>h<SUP>± </SUP>decays with D→K<SUP>0</SUP><sub>S</sub>h<SUP>+</SUP>h<SUP>-</SUP>(h=π,K)
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2024,
Higher-order moments of the elliptic flow distribution in PbPb collisions at √<i>s</i><sub>NN</sub>=5.02 TeV
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articlePal K, Das I, 2024,
Exploring the exchange bias of Gd and MnPt: A combined structural and magnetic investigation
, Thin Solid Films, Vol: 790, ISSN: 0040-6090Magnetic manipulation in thin films is essential for modern technology. Extensive studies on exchange bias with antiferromagnetic materials and transition metals exist, but research on rare earth elements is limited. This study investigates the formation of the L10-MnPt phase and a ferromagnetic-like Gd phase on Si/SiO2 thin films. We observed thickness-dependent anisotropic magnetic fields in Gd thin films and thickness-dependent exchange bias in the heterojunctions. These findings enhance our understanding of the magnetic properties of MnPt, Gd and the multilayer heterostructure.
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Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Measurement of the Zboson production cross-section inp pcollisions at √s=5.02TeV
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Production of η and<i> η'</i> mesons in<i> pp</i> and pPb collisions
, PHYSICAL REVIEW C, Vol: 109, ISSN: 2469-9985 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for Scalar Leptoquarks Produced via τ-Lepton-Quark Scattering in pp Collisions at ffiffi s p=13 TeV
, PHYSICAL REVIEW LETTERS, Vol: 132, ISSN: 0031-9007 -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Improved Measurement of CP Violation Parameters in B0s → J=ψK plus K - Decays in the Vicinity of the φ(1020) Resonance
, PHYSICAL REVIEW LETTERS, Vol: 132, ISSN: 0031-9007 -
Journal articleMondal N, Mazumdar D, Chatterjee S, et al., 2024,
Exploring complex magnetic phase transitions and magnetocaloric effect in the nanocrystalline Nd<inf>0.5</inf>Ca<inf>0.5</inf>MnO<inf>3</inf> compound
, Ceramics International, Vol: 50, Pages: 5594-5603, ISSN: 0272-8842In this article, we have investigated the temperature and magnetic field-induced complex magnetic phases and magnetocaloric properties of the nanocrystalline Nd0.5Ca0.5MnO3 (NCMO) compound in detail. The compound exhibits charge-ordered antiferromagnetic (CO-AFM) and charge-orbital-ordered antiferromagnetic (AFM) phases at TCO≃ 225 K and TN= 160 K respectively. At the intermediate temperature range, i.e. TN≤ T ≤ TCO, an unfamiliar magnetic state is present where the orbital ordering of manganese ions sets progressively. Both the short-range and zig-zag ordered ferromagnetic (FM) chains and an AFM phase coexist within this temperature window. The effect of magnetic field and temperature drastically modifies the fragile magnetic ground state and this change is also reflected in the magnetocaloric properties of the studied compound. At the low-temperature region, an inverse magnetocaloric effect (MCE) is noticed due to the kinetically arrested magnetic moments of the AFM phase. However, a conventional MCE is noticed in the high-temperature regime. The anomalous behavior of the MCE in the nanocrystalline NCMO compound is analyzed by considering the effect of the reduction of particle size and the meta-stable nature of the magnetic ground state. In addition, we have paid attention to the hysteretic losses associated with the first-order phase transition (FOPT) in order to estimate the magnetic cooling capacity for the material. These studies carry notable importance for the usefulness of nanocrystalline half-doped manganite compounds not only for basic scientific research purpose, but also having possible practical utilization in the magnetic refrigeration industries.
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