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Conference paperIovine N, Abe K, Bronner C, et al., 2024,
Search for Boosted Dark Matter in Super-Kamiokande with low-energy electrons
Despite efforts from numerous experiments to grasp the nature of dark matter, no convincing dark matter signal has been observed so far and the very properties of this invisible matter remain unknown. Nevertheless, strong constraints on these properties are set by current observations, particularly for GeV to TeV WIMP-like dark matter particles. In contrast, sub-GeV dark matter scenarios are largely unexplored and still offer promising prospects for dark matter detection. In this contribution, we conduct a search for low-energy electrons scattered by boosted dark matter particles in the Super-Kamiokande detector. In particular, a two-component dark matter scenario is considered, which results in a natural boosting of the non-secluded secondary dark matter particles produced by the decay or annihilation of the dominant cold dark matter component. This work focuses on boosted dark matter from the centre of our Galaxy, with scattered electron energies ranging from a few MeV to a few hundred of MeV. We present the first sensitivities of such low-energy boosted dark matter search using Super-Kamiokande.
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Conference paperHarada M, Abe K, Bronner C, et al., 2024,
First result of a search for Diffuse Supernova Neutrino Background in SK-Gd experiment
Since 2020, Super-Kamiokande (SK) detector has been updated by loading gadolinium (Gd) as a new experimental phase, ‘SK-Gd.’ In the SK-Gd experiment, we can search low-energy electron antineutrinos via inverse-beta decay with efficient neutron identification thanks to high cross-section and high-energy gamma-ray emission of thermal neutron capture on Gd. Until July 2022, the observation is operated with the 0.01% Gd mass concentration. The neutron capture fraction on Gd is about 50% in this situation. In this paper, the first search result for the flux of astrophysical electron antineutrinos for the energy range of O(10) MeV in SK-Gd with a 22.5 × 552 kton·day exposure at 0.01% Gd mass concentration of the initial stage of SK-Gd is reported.
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Conference paperShinoki M, Abe K, Bronner C, et al., 2024,
Measurement of cosmogenic <sup>9</sup>Li in Super-Kamiokande with gadolinium loaded water
Super-Kamiokande is a large water Cherenkov detector located approximately 1,000 m underground in Kamioka, Japan. The detector is a cylindrical tank 39.3 m in diameter and 41.4 m high, filled with about 50 kton of gadolinium loaded water. We measured 9Li isotopic nuclei produced by muon spallation using the data taken from 2020 to 2022 by the Super-Kamiokande detector with 0.011% gadolinium concentration in water. Cosmic-ray muons that penetrate the detector form hadron showers in water and secondary hadrons produce unstable radioisotopes through the spallation. Among those spallation products, 9Li is a long-lived radioactive isotope with a lifetime of about 0.26 seconds. It emits an electron and a neutron at a branching ratio of 50.8%, which is difficult to distinguish from the inverse beta decay caused by electron antineutrinos. Therefore, 9Li is one of the main background sources in the observation of diffuse supernova neutrino background. In this study, the energy spectrum of the electrons was measured with a threshold at 4.5 MeV which is lowered from the previous result with pure water. We will report the analysis method and results.
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Conference paperTada T, Nakano Y, Koshio Y, et al., 2024,
Measurement of the kaon to pion production ratio with the Super-Kamiokande
Cosmic-ray muons are generated from the decay of mesons which are secondary particles produced via hadronic interaction between primary cosmic-ray particles and atmospheric nuclei at the upper the atmosphere. The mesons such pions and kaons mostly decay into muons immediately, reflecting the details of the hadronic interactions depending on their energy and lifetime. The modulation of the cosmic-ray muon rate as well as the flux and the atmospheric kaon-to-pion production ratio are important to determine the flux and energy of the atmospheric neutrino. In particular, the kaon-to-pion production ratio rK/π is measured with the correlation coefficient αT between the cosmic-ray muon rate in the underground detector and the atmospheric temperature. As a result, we obtained the correlation coefficient rK/π = 0.85 ± 0.01 (statistical uncertainty only) and rK/π = 0.12 ± 0.03 (statistical uncertainty only) using the data taken in 10 years at the Super-Kamiokande detector. In this article, we report the current status of measurement of the modulation of the comic-ray muon and the atmospheric kaon-to-pion production ratio.
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Conference paperSakai S, Abe K, Bronner C, et al., 2024,
Study of the neutrino-oxygen neutral-current quasielastic cross section using atmospheric neutrinos in the SK-Gd experiment
The atmospheric neutrino-oxygen neutral-current quasielasatic (NCQE) reactions are one of the main background in the search for supernova relic neutrinos. Here, we report the first measurement of the atmospheric neutrino-oxygen NCQE cross section in the Super-Kamiokande Gadolinium (SK-Gd) experiment using 552.2 days of full SK-VI data. The measured NCQE cross section is 0.74 ± 0.22(stat.) +−0.860.16(syst.) × 10−38 cm2, which is consistent with the theoretical NCQE cross section and the previous study in SK within the range of the uncertainty. Furthermore, we established the verification method for nucleon-nucleus interaction models using atmospheric neutrino events. We performed the verification using the Bertini Cascade model (BERT), the Binary Cascade model (BIC) and the Liège Intranuclear Cascade model (INCL++). As a result, we suggested that BIC and INCL++ are closer to the observed data.
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Conference paperHino Y, Abe K, Bronner C, et al., 2024,
Status and Prospect of SK-Gd Project
In 2020, a new phase of Super-Kamiokande experiment, SK-Gd, was started by loading gadolinium into the pure water. This led to a high neutron detection efficiency, which allows us to distinguish different neutrino reactions, enhance signals and remove backgrounds more efficiently. In the summer of 2022, an update of SK-Gd was done by adding additional Gd, and thus totally 39 tonnes of gadolinium sulfate octahydrate has been introduced in the water. The Gd concentration was estimated as 0.0332±0.0002% based on the dissolved weight of gadolinium sulfate octahydrate powder. It is consistent with the result of the direct sampling from the detector as 334 ± 4 ppm. The spallation neutron measurement and AmBe calibration confirms the shorter capture time constant and higher capture event rate due to the second loading. Therefore, we achieved 1.5 times higher than that of the first loaded phase as expected.
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Conference paperNakano Y, Tada T, Kitagawa H, et al., 2024,
Measurement of the charge ratio and polarization of cosmic-ray muon using the tagged decay-e events in Super-Kamiokande
Neutrinos and muons from cosmic-ray interactions in the atmosphere originate from mesons, such as pions and kaons, in air-showers. An accuracy of the absolute atmospheric neutrino flux and its flavor ratio are limited due to the uncertainty of meson productions in hadronic interaction models. In order to reduce such uncertainty, measurements of the charge ratio and the polarization of cosmic-ray muons are important as new inputs to theoretical models which simulate the atmospheric neutrino flux. In this proceedings, we present the results of the charge ratio (R) and polarization (Pμ0) of cosmic-ray muon measurements using the decay electrons collected from 2008 September to 2022 June by the Super-Kamiokande (SK) detector. We measured muon charge ratio to be R = 1.32±0.02 (stat.+syst.) and the muon polarization at the production location to be Pμ0 = 0.52±0.01 (stat.+syst.). The SK detector uniquely measured the polarization of cosmic-ray muons with energies more than 1 TeV at sea-level because of its underground location.
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Conference paperNakanishi F, Abe K, Bronner C, et al., 2024,
Evaluation of neutron tagging efficiency on 0.03% Gd mass concentration in SK-Gd experiment
Super-Kamiokande (SK) experiment started the "SK-Gd experiment" by dissolving gadolinium (Gd) sulfate octa-hydrate in ultra-pure water from the tank in July 2020. The neutron tagging efficiency has been improved compared to the pure-water phase by detecting a total energy of 8 MeV gamma rays emitted by thermal neutron capture on Gd. It enables us to improve, for example, the sensitivity of diffuse supernova neutrino background, the accuracy of the reconstruction for the supernova direction, and so on. For these physics targets, accurate evaluation of neutron identification efficiency is essential. In this presentation, I report the calibration results using an Am/Be neutron source to evaluate the efficiency at a Gd mass concentration of 0.03%, starting from June 2022, and the comparison of the estimated neutron detection efficiency with simulation.
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Conference paperWang X, Abe K, Bronner C, et al., 2024,
Time-dependent and Time-independent Directional Search for High-Energy Astrophysical Neutrino Point Sources in Super-Kamiokande
This contribution reports the results of the searches for high-energy astrophysical neutrino point sources in the energy range above GeV using Super-Kamiokande data. The searches include time-integrated and time-dependent full sky searches for both νμ and νe sources and coincidence check with candidates including TXS 0506+056 and NGC 1068. The searches use unbinned maximum likelihood method, and test statistics is calculated to find signal excess over atmospheric neutrino background. The time-integrated search method is updated from a previous search by adding the neutrino energy distribution in the likelihood to consider different power-law emission spectra with varying spectral indices. This is the first time to perform the time-dependent search, which has a better performance in searching for neutrino emission in a short time period, in Super-Kamiokande. Upper limits on neutrino flux or fluence are set for all searches.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Observation of New Charmonium or Charmoniumlike States in B^{+}→D^{*±}D^{∓}K^{+} Decays.
, Phys Rev Lett, Vol: 133A study of resonant structures in B^{+}→D^{*+}D^{-}K^{+} and B^{+}→D^{*-}D^{+}K^{+} decays is performed, using proton-proton collision data at center-of-mass energies of sqrt[s]=7, 8, and 13 TeV recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb^{-1}. A simultaneous amplitude fit is performed to the two channels with contributions from resonances decaying to D^{*-}D^{+} and D^{*+}D^{-} states linked by C parity. This procedure allows the C parities of resonances in the D^{*±}D^{∓} mass spectra to be determined. Four charmonium or charmoniumlike states are observed decaying into D^{*±}D^{∓}: η_{c}(3945), h_{c}(4000), χ_{c1}(4010), and h_{c}(4300), with quantum numbers J^{PC} equal to 0^{-+}, 1^{+-}, 1^{++}, and 1^{+-}, respectively. At least three of these states have not been observed previously. In addition, the existence of the T_{c[over ¯]s[over ¯]0}^{*}(2870)^{0} and T_{c[over ¯]s[over ¯]1}^{*}(2900)^{0} resonances in the D^{-}K^{+} mass spectrum, already observed in the B^{+}→D^{+}D^{-}K^{+} decay, is confirmed in a different production channel.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Search for Time-Dependent CP Violation in D^{0}→π^{+}π^{-}π^{0} Decays.
, Phys Rev Lett, Vol: 133A measurement of time-dependent CP violation in D^{0}→π^{+}π^{-}π^{0} decays using a pp collision data sample collected by the LHCb experiment in 2012 and from 2015 to 2018, corresponding to an integrated luminosity of 7.7 fb^{-1}, is presented. The initial flavor of each D^{0} candidate is determined from the charge of the pion produced in the D^{*}(2010)^{+}→D^{0}π^{+} decay. The decay D^{0}→K^{-}π^{+}π^{0} is used as a control channel to validate the measurement procedure. The gradient of the time-dependent CP asymmetry ΔY in D^{0}→π^{+}π^{-}π^{0} decays is measured to be ΔY=(-1.3±6.3±2.4)×10^{-4}, where the first uncertainty is statistical and the second is systematic, which is compatible with CP conservation.
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Journal articleArmano M, Audley H, Baird J, et al., 2024,
Tilt-to-length coupling in LISA Pathfinder: Long-term stability
, PHYSICAL REVIEW D, Vol: 110, ISSN: 2470-0010 -
Journal articleCms Collaboration T, 2024,
Observation ofγγ→ττin proton-proton collisions and limits on the anomalous electromagnetic moments of the τ lepton.
, Rep Prog Phys, Vol: 87The production of a pair of τ leptons via photon-photon fusion,γγ→ττ, is observed for the first time in proton-proton collisions, with a significance of 5.3 standard deviations. This observation is based on a data set recorded with the CMS detector at the LHC at a center-of-mass energy of 13 TeV and corresponding to an integrated luminosity of 138 fb-1. Events with a pair of τ leptons produced via photon-photon fusion are selected by requiring them to be back-to-back in the azimuthal direction and to have a minimum number of charged hadrons associated with their production vertex. The τ leptons are reconstructed in their leptonic and hadronic decay modes. The measured fiducial cross section ofγγ→ττisσobsfid=12.4-3.1+3.8fb. Constraints are set on the contributions to the anomalous magnetic moment (aτ) and electric dipole moments (dτ) of the τ lepton originating from potential effects of new physics on theγττvertex:aτ=0.0009-0.0031+0.0032and|dτ|<2.9×10-17ecm(95% confidence level), consistent with the standard model.
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Journal articleAbed Abud A, Abi B, Acciarri R, et al., 2024,
Performance of a Modular Ton-Scale Pixel-Readout Liquid Argon Time Projection Chamber
, Instruments, Vol: 8The Module-0 Demonstrator is a single-phase 600 kg liquid argon time projection chamber operated as a prototype for the DUNE liquid argon near detector. Based on the ArgonCube design concept, Module-0 features a novel 80k-channel pixelated charge readout and advanced high-coverage photon detection system. In this paper, we present an analysis of an eight-day data set consisting of 25 million cosmic ray events collected in the spring of 2021. We use this sample to demonstrate the imaging performance of the charge and light readout systems as well as the signal correlations between the two. We also report argon purity and detector uniformity measurements and provide comparisons to detector simulations.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Transverse polarization measurement of Λ hyperons in pNe collisions at sNN = 68.4 GeV with the LHCb detector
, Journal of High Energy Physics, Vol: 2024A measurement of the transverse polarization of the Λ and Λ¯ hyperons in pNe fixed-target collisions at sNN = 68.4 GeV is presented using data collected by the LHCb detector. The polarization is studied using the decay Λ → pπ− together with its charge conjugated process, the integrated values measured are (Formula presented.) Furthermore, the results are shown as a function of the Feynman x variable, transverse momentum, pseudorapidity and rapidity of the hyperons, and are compared with previous measurements.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Search for the rare decay of charmed baryon Λc+ into the pμ+μ- final state
, Physical Review D, Vol: 110, ISSN: 2470-0010A search for the nonresonant Λc+→pμ+μ- decay is performed using proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4 fb-1. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the Λc+→pμ+μ- decay is determined to be 2.9(3.2)×10-8 at 90%(95%) confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the η, ρ and ω resonances are also determined.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for bottom-type vectorlike quark pair production in dileptonic and fully hadronic final states in proton-proton collisions at √𝑠 =13 TeV
, Physical Review D, Vol: 110, ISSN: 2470-0010A search is described for the production of a pair of bottom-type vectorlike quarks (𝐵 VLQs) with mass greater than 1000 GeV. Each 𝐵 VLQ decays into a 𝑏 quark and a Higgs boson, a 𝑏 quark and a 𝑍 boson, or a 𝑡 quark and a 𝑊 boson. This analysis considers both fully hadronic final states and those containing a charged lepton pair from a 𝑍 boson decay. The products of the 𝐻 →𝑏𝑏 boson decay and of the hadronic 𝑍 or 𝑊 boson decays can be resolved as two distinct jets or merged into a single jet, so the final states are classified by the number of reconstructed jets. The analysis uses data corresponding to an integrated luminosity of 138 fb−1 collected in proton-proton collisions at √𝑠 =13 TeV with the CMS detector at the LHC from 2016 to 2018. No excess over the expected background is observed. Lower limits are set on the 𝐵 VLQ mass at the 95% confidence level. These depend on the 𝐵 VLQ branching fractions and are 1570 and 1540 GeV for 100% 𝐵 →𝑏𝐻 and 100% 𝐵 →𝑏𝑍, respectively. In most cases, the mass limits obtained exceed previous limits by at least 100 GeV.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for a resonance decaying to a W boson and a photon in proton-proton collisions at s = 13 TeV using leptonic W boson decays
, Journal of High Energy Physics, Vol: 2024A search for a new charged particle X with mass between 0.3 and 2.0 TeV decaying to a W boson and a photon is presented, using proton-proton collision data at a center-of-mass energy of 13 TeV, collected by the CMS experiment and corresponding to an integrated luminosity of 138 fb−1. Particle X has electric charge ±1 and is assumed to have spin 0. The search is performed using the electron and muon decays of the W boson. No significant excess above the predicted background is observed. The upper limit at 95% confidence level on the product of the production cross section of the X and its branching fraction to a W boson and a photon is found to be 94 (137) fb for a 0.3 TeV resonance and 0.75 (0.81) fb for a 2.0 TeV resonance, for an X width-to-mass ratio of 0.01% (5%). This search presents the most stringent constraints to date on the existence of such resonances across the probed mass range. A statistical combination with an earlier study based on the hadronic decay mode of the W boson is also performed, and the upper limit at 95% confidence level for a 2.0 TeV resonance is reduced to 0.50 (0.63) fb for an X width-to-mass ratio of 0.01% (5%).
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Comprehensive analysis of local and nonlocal amplitudes in the B<sup>0</sup>→ K<sup>*0</sup>μ<sup>+</sup>μ<sup>−</sup> decay
, Journal of High Energy Physics, Vol: 2024A comprehensive study of the local and nonlocal amplitudes contributing to the decay B0 → K*0(→ K+π−)μ+μ− is performed by analysing the phase-space distribution of the decay products. The analysis is based on pp collision data corresponding to an integrated luminosity of 8.4 fb−1 collected by the LHCb experiment. This measurement employs for the first time a model of both one-particle and two-particle nonlocal amplitudes, and utilises the complete dimuon mass spectrum without any veto regions around the narrow charmonium resonances. In this way it is possible to explicitly isolate the local and nonlocal contributions and capture the interference between them. The results show that interference with nonlocal contributions, although larger than predicted, only has a minor impact on the Wilson Coefficients determined from the fit to the data. For the local contributions, the Wilson Coefficient C9, responsible for vector dimuon currents, exhibits a 2.1σ deviation from the Standard Model expectation. The Wilson Coefficients C10, C9′ and C10′ are all in better agreement than C9 with the Standard Model and the global significance is at the level of 1.5σ. The model used also accounts for nonlocal contributions from B0→ K*0[τ+τ−→ μ+μ−] rescattering, resulting in the first direct measurement of the bsττ vector effective-coupling C9τ.
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Journal articleOdagiu P, Que Z, Duarte J, et al., 2024,
Ultrafast jet classification at the HL-LHC
, Machine Learning: Science and Technology, Vol: 5, ISSN: 2632-2153Three machine learning models are used to perform jet origin classification. These models are optimized for deployment on a field-programmable gate array device. In this context, we demonstrate how latency and resource consumption scale with the input size and choice of algorithm. Moreover, the models proposed here are designed to work on the type of data and under the foreseen conditions at the CERN large hadron collider during its high-luminosity phase. Through quantization-aware training and efficient synthetization for a specific field programmable gate array, we show that O(100) ns inference of complex architectures such as Deep Sets and Interaction Networks is feasible at a relatively low computational resource cost.
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Journal articleMcGarrigle JM, Long KR, Prezado Y, 2024,
On the significance of the different geometrical and dosimetric parameters in microbeam and minibeam radiation therapy a retrospective evaluation
, Frontiers in Oncology, Vol: 14, ISSN: 2234-943XIntroduction: Spatially Fractionated Radiation Therapy (SFRT) is an unconventional therapeutic approach with the potential to disrupt the classical paradigms of conventional radiation therapy. The high spatial dose modulation in SFRT is believed to activate distinct radiobiological mechanisms which lead to remarkable increases in normal tissue tolerance. To make optimal use of SFRT and its benefits, a deeper understanding of the biological response and its relationship with the complex dosimetric and geometric components of SFRT is essential.Method: A retrospective evaluation of preclinical studies was conducted to gain insight into the dosimetric and geometric parameters that are most correlated with normal tissue response. Current literature evaluates the response of tissue to MBRT and MRT according to various end points, e.g. the level of desquamation, degree of necrosis, or the amount of malcalcification. A set of metrics was developed to allow a quantitative comparison of these results.Results: The strongest correlations were observed with the doses in both the peaks and valleys as well as the ratio of the area covered by the peak over the total area. This emphasises the geometry of the beam. MBRT challenged previous uniform dose-distribution paradigms by highlighting the critical role of Peak Dose alongside Valley Dose in tissue sparing whereas MRT underscores the significant influence of geometric beam parameters on tissue preservation.Discussion: The data exhibits variability in the results obtained using different animal models and endpoints and additional research is warranted to explore the trends observed in this study under controlled conditions.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Performance of CMS muon reconstruction from proton-proton to heavy ion collisions
, Journal of Instrumentation, Vol: 19, ISSN: 1748-0221The performance of muon tracking, identification, triggering, momentum resolution, and momentum scale has been studied with the CMS detector at the LHC using data collected at √(sNN) = 5.02 TeV in proton-proton (pp) and lead-lead (PbPb) collisions in 2017 and 2018, respectively, and at √(sNN) = 8.16 TeV in proton-lead (pPb) collisions in 2016. Muon efficiencies, momentum resolutions, and momentum scales are compared by focusing on how the muon reconstruction performance varies from relatively small occupancy pp collisions to the larger occupancies of pPb collisions and, finally, to the highest track multiplicity PbPb collisions. We find the efficiencies of muon tracking, identification, and triggering to be above 90% throughout most of the track multiplicity range. The momentum resolution and scale are unaffected by the detector occupancy. The excellent muon reconstruction of the CMS detector enables precision studies across all available collision systems.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Performance of the CMS electromagnetic calorimeter in pp collisions at √s = 13 TeV
, Journal of Instrumentation, Vol: 19, Pages: P09004-P09004, ISSN: 1748-0221The operation and performance of the Compact Muon Solenoid (CMS) electromagnetic calorimeter (ECAL) are presented, based on data collected in pp collisions at √s =13 TeV at the CERN LHC, in the years from 2015 to 2018 (LHC Run 2), corresponding to an integrated luminosity of 151 fb-1. The CMS ECAL is a scintillating lead-tungstate crystal calorimeter, with a silicon strip preshower detector in the forward region that provides precise measurements of the energy and the time-of-arrival of electrons and photons. The successful operation of the ECAL is crucial for a broad range of physics goals, ranging from observing the Higgs boson and measuring its properties, to other standard model measurements and searches for new phenomena. Precise calibration, alignment, and monitoring of the ECAL response are important ingredients to achieve these goals. To face the challenges posed by the higher luminosity, which characterized the operation of the LHC in Run 2, the procedures established during the 2011–2012 run of the LHC have been revisited and new methods have been developed for the energy measurement and for the ECAL calibration. The energy resolution of the calorimeter, for electrons from Z boson decays reaching the ECAL without significant loss of energy by bremsstrahlung, was better than 1.8%, 3.0%, and 4.5% in the |η| intervals [0.0,0.8], [0.8,1.5], [1.5, 2.5], respectively. This resulting performance is similar to that achieved during Run 1 in 2011–2012, in spite of the more severe running conditions.
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Journal articleAalbers J, Akerib DS, Al Musalhi AK, et al., 2024,
Probing the scalar WIMP-pion coupling with the first LUX-ZEPLIN data
, Communications Physics, Vol: 7, ISSN: 2399-3650Weakly interacting massive particles (WIMPs) may interact with a virtual pion that is exchanged between nucleons. This interaction channel is important to consider in models where the spin-independent isoscalar channel is suppressed. Using data from the first science run of the LUX-ZEPLIN dark matter experiment, containing 60 live days of data in a 5.5 tonne fiducial mass of liquid xenon, we report the results on a search for WIMP-pion interactions. We observe no significant excess and set an upper limit of 1.5 × 10−46 cm2 at a 90% confidence level for a WIMP mass of 33 GeV/c2 for this interaction.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Observation of strangeness enhancement with charmed mesons in high-multiplicity <i>p</i>Pb collisions at √<i>s</i><sub>NN</sub>=8.16 TeV
, PHYSICAL REVIEW D, Vol: 110, ISSN: 2470-0010 -
Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
First observation of Λ<i><sub>b</sub></i><SUP>0</SUP> → Σ<i><sub>c</sub></i><SUP>(</SUP>*<SUP>)+ +</SUP> <i>D</i><SUP>(</SUP>*<SUP>) -</SUP> <i>K</i><SUP>-</SUP> decays
, PHYSICAL REVIEW D, Vol: 110, ISSN: 2470-0010 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Measurement of multijet azimuthal correlations and determination of the strong coupling in proton-proton collisions at s = 13 TeV
, European Physical Journal C: Particles and Fields, Vol: 84, ISSN: 1124-1861A measurement is presented of a ratio observable that provides a measure of the azimuthal correlationsamong jets with large transverse momentum pT . This observable is measured in multijet events over the range of pT = 360–3170 GeV based on data collected by the CMS experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 134 fb−1 . The results are compared with predictions fromMonte Carlo parton-shower event generator simulations, aswell as with fixed-order perturbative quantum chromodynamics (pQCD) predictions at next-to-leading-order (NLO) accuracy obtained with different parton distribution functions (PDFs) and corrected for nonperturbative and electroweak effects. Data and theory agree within uncertainties. From the comparison of the measured observable with the pQCD prediction obtained with the NNPDF3.1 NLO PDFs, the strong coupling at the Z boson mass scale is αS(mZ) = 0.1177 ± 0.0013 (exp)+0.0116−0.0073 (theo) = 0.1177+0.0117−0.0074 , where the total uncertainty is dominated by the scale dependenceof the fixed-order predictions. A test of the running of αS inthe TeV region shows no deviation from the expected NLOpQCD behaviour.
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Journal articleArmano M, Audley H, Baird J, et al., 2024,
In-depth analysis of LISA Pathfinder performance results: Time evolution, noise projection, physical models, and implications for LISA
, Physical Review D, Vol: 110, ISSN: 2470-0010We present an in-depth analysis of the LISA Pathfinder differential acceleration performance over the entire course of its science operations, spanning approximately 500 days. We find: (1) The evolution of the Brownian noise that dominates the acceleration amplitude spectral density (ASD), for frequencies f≳1 mHz, is consistent with the decaying pressure due to the outgassing of a single gaseous species. (2) Between f=36 μHz and 1 mHz, the acceleration ASD shows a 1/f tail in excess of the Brownian noise of almost constant amplitude, with ≃20% fluctuations over a period of a few days, with no particular time pattern over the course of the mission. (3) At the lowest considered frequency of f=18 μHz, the ASD significantly deviates from the 1/f behavior, because of temperature fluctuations that appear to modulate a quasistatic pressure gradient, sustained by the asymmetries of the outgassing pattern. We also present the results of a projection of the observed acceleration noise on the potential sources for which we had either a direct correlation measurement or a quantitative estimate from dedicated experiments. These sources account for approximately 40% of the noise power in the 1/f tail. Finally, we analyze the possible sources of the remaining unexplained fraction and identify the possible measures that may be taken to keep those under control in LISA.
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Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Amplitude analysis of the radiative decay B<sub>s</sub><SUP>0</SUP> → K<SUP>+</SUP>K<SUP>-</SUP>γ
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Combination of measurements of the top quark mass from data collected by the ATLAS and CMS experiments at sqrt[s]=7 and 8 TeV
, Physical Review Letters, Vol: 132, ISSN: 0031-9007A combination of fifteen top quark mass measurements performed by the ATLAS and CMS experiments at the LHC is presented. The datasets used correspond to an integrated luminosity of up to 5 and 20 fb−1 of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, respectively. The combination includes measurements in top quark pair events that exploit both the semileptonic and hadronic decays of the top quark, and a measurement using events enriched in single top quark production via the electroweak 𝑡 channel. The combination accounts for the correlations between measurements and achieves an improvement in the total uncertainty of 31% relative to the most precise input measurement. The result is 𝑚𝑡=172.52±0.14(stat)±0.30(syst) GeV, with a total uncertainty of 0.33 GeV.
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