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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Multiplicity dependence of σ<inf>ψ(2S)</inf>/σ<inf>J/ψ</inf> in pp collisions at √s = 13 TeV
, Journal of High Energy Physics, Vol: 2024The ratio of production cross-sections of ψ(2S) over J/ψ mesons as a function of charged-particle multiplicity in proton-proton collisions at a centre-of-mass energy s = 13 TeV is measured with a data sample collected by the LHCb detector, corresponding to an integrated luminosity of 658 pb−1. The ratio is measured for both prompt and non-prompt ψ(2S) and J/ψ mesons. When there is an overlap between the rapidity ranges over which multiplicity and charmonia production are measured, a multiplicity-dependent modification of the ratio is observed for prompt mesons. No significant multiplicity dependence is found when the ranges do not overlap. For non-prompt production, the ψ(2S)-to-J/ψ production ratio is roughly independent of multiplicity, irrespective of the rapidity range over which the multiplicity is measured. The results are compared to predictions of the co-mover model and agree well except in the low multiplicity region. The ratio of production cross-sections of ψ(2S) over J/ψ mesons are cross-checked with other measurements in di-lepton channels and found to be compatible.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
A measurement of ∆Γ<inf>s</inf>
, Journal of High Energy Physics, Vol: 2024Using a dataset corresponding to 9 fb−1 of integrated luminosity collected with the LHCb detector between 2011 and 2018 in proton-proton collisions, the decay-time distributions of the decay modes Bs0→J/ψη′ and Bs0→J/ψπ+π− are studied. The decay-width difference between the light and heavy mass eigenstates of the Bs0 meson is measured to be ∆Γs = 0.087 ± 0.012 ± 0.009 ps−1, where the first uncertainty is statistical and the second systematic.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Measurements of the branching fraction ratio B(ϕ→μ<sup>+</sup>μ<sup>−</sup>)/B(ϕ→e<sup>+</sup>e<sup>−</sup>) with charm meson decays
, Journal of High Energy Physics, Vol: 2024Measurements of the branching fraction ratio B(ϕ→μ+μ−)/B(ϕ→e+e−) with Ds+→π+ϕ and D+→ π+ϕ decays, denoted Rϕπs and Rϕπd, are presented. The analysis is performed using a dataset corresponding to an integrated luminosity of 5.4 fb−1 of pp collision data collected with the LHCb experiment. The branching fractions are normalised with respect to the B+ → K+J/ψ(→ e+e−) and B+ → K+J/ψ(→ μ+μ−) decay modes. The combination of the results yields (Formula presented.) The result is compatible with previous measurements of the ϕ → ℓ+ℓ− branching fractions and predictions based on the Standard Model.
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Journal articleAyres Rocha D, Baptista de Souza Leite J, Bediaga IB, et al., 2024,
The LHCb Upgrade I
, Journal of Instrumentation, Vol: 19The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Measurement of associated J/ψ-ψ(2S) production cross-section in pp collisions at √s = 13 TeV
, Journal of High Energy Physics, Vol: 2024The cross-section of associated J/ψ-ψ(2S) production in proton-proton collisions at a centre-of-mass energy of (Formula presented.) TeV is measured using a data sample corresponding to an integrated luminosity of 4.2 fb−1, collected by the LHCb experiment. The measurement is performed for both J/ψ and ψ(2S) mesons having transverse momentum pT< 14 GeV/c and rapidity 2.0 < y < 4.5, assuming negligible polarisation of the J/ψ and ψ(2S) mesons. The production cross-section is measured to be 4.5 ± 0.7 ± 0.3 nb, where the first uncertainty is statistical and the second systematic. The differential cross-sections are measured as functions of several kinematic variables of the J/ψ-ψ(2S) candidates. The results are combined with a measurement of J/ψ-J/ψ production, giving a cross-section ratio between J/ψ-ψ(2S) and J/ψ-J/ψ production of 0.274 ± 0.044 ± 0.008, where the first uncertainty is statistical and the second systematic.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2024,
Development of the CMS detector for the CERN LHC Run 3
, Journal of Instrumentation, Vol: 19Since the initial data taking of the CERN LHC, the CMS experiment has undergone substantial upgrades and improvements. This paper discusses the CMS detector as it is configured for the third data-taking period of the CERN LHC, Run 3, which started in 2022. The entire silicon pixel tracking detector was replaced. A new powering system for the superconducting solenoid was installed. The electronics of the hadron calorimeter was upgraded. All the muon electronic systems were upgraded, and new muon detector stations were added, including a gas electron multiplier detector. The precision proton spectrometer was upgraded. The dedicated luminosity detectors and the beam loss monitor were refurbished. Substantial improvements to the trigger, data acquisition, software, and computing systems were also implemented, including a new hybrid CPU/GPU farm for the high-level trigger.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Measurement of the primary Lund jet plane density in proton-proton collisions at s = 13 TeV
, Journal of High Energy Physics, Vol: 2024A measurement is presented of the primary Lund jet plane (LJP) density in inclusive jet production in proton-proton collisions. The analysis uses 138 fb−1 of data collected by the CMS experiment at s = 13 TeV. The LJP, a representation of the phase space of emissions inside jets, is constructed using iterative jet declustering. The transverse momentum kT and the splitting angle ∆R of an emission relative to its emitter are measured at each step of the jet declustering process. The average density of emissions as function of ln(kT/GeV) and ln(R/∆R) is measured for jets with distance parameters R = 0.4 or 0.8, transverse momentum pT> 700 GeV, and rapidity |y| < 1.7. The jet substructure is measured using the charged-particle tracks of the jet. The measured distributions, unfolded to the level of stable charged particles, are compared with theoretical predictions from simulations and with perturbative quantum chromodynamics calculations. Due to the ability of the LJP to factorize physical effects, these measurements can be used to improve different aspects of the physics modeling in event generators.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2024,
Search for a new resonance decaying into two spin-0 bosons in a final state with two photons and two bottom quarks in proton-proton collisions at (Formula presented.)
, Journal of High Energy Physics, Vol: 2024A search for a new boson X is presented using CERN LHC proton-proton collision data collected by the CMS experiment at s = 13 TeV in 2016–2018, and corresponding to an integrated luminosity of 138 fb−1. The resonance X decays into either a pair of Higgs bosons HH of mass 125 GeV or an H and a new spin-0 boson Y. One H subsequently decays to a pair of photons, and the second H or Y, to a pair of bottom quarks. The explored mass ranges of X are 260–1000 GeV and 300–1000 GeV, for decays to HH and to HY, respectively, with the Y mass range being 90–800 GeV. For a spin-0 X hypothesis, the 95% confidence level upper limit on the product of its production cross section and decay branching fraction is observed to be within 0.90–0.04 fb, depending on the masses of X and Y. The largest deviation from the background-only hypothesis with a local (global) significance of 3.8 (below 2.8) standard deviations is observed for X and Y masses of 650 and 90 GeV, respectively. The limits are interpreted using several models of new physics.
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Journal articleTumasyan A, Adam W, Andrejkovic JW, et al., 2024,
Measurement of simplified template cross sections of the Higgs boson produced in association with w or z bosons in the Formula Presented decay channel in proton-proton collisions at Formula Presented
, Physical Review D, Vol: 109, ISSN: 2470-0010Differential cross sections are measured for the standard model Higgs boson produced in association with vector bosons (Formula Presented, Formula Presented) and decaying to a pair of Formula Presented quarks. Measurements are performed within the framework of the simplified template cross sections. The analysis relies on the leptonic decays of the Formula Presented and Formula Presented bosons, resulting in final states with 0, 1, or 2 electrons or muons. The Higgs boson candidates are either reconstructed from pairs of resolved Formula Presented-tagged jets, or from single large-radius jets containing the particles arising from two Formula Presented quarks. Proton-proton collision data at Formula Presented, collected by the CMS experiment in 2016-2018 and corresponding to a total integrated luminosity of Formula Presented, are analyzed. The inclusive signal strength, defined as the product of the observed production cross section and branching fraction relative to the standard model expectation, combining all analysis categories, is found to be Formula Presented. This corresponds to an observed (expected) significance of 6.3 (5.6) standard deviations.
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Journal articleAcampora G, Ahdida C, Albanese R, et al., 2024,
SND@LHC: the scattering and neutrino detector at the LHC
, Journal of Instrumentation, Vol: 19SND@LHC is a compact and stand-alone experiment designed to perform measurements with neutrinos produced at the LHC in the pseudo-rapidity region of 7.2 < η < 8.4. The experiment is located 480 m downstream of the ATLAS interaction point, in the TI18 tunnel. The detector is composed of a hybrid system based on an 830 kg target made of tungsten plates, interleaved with emulsion and electronic trackers, also acting as an electromagnetic calorimeter, and followed by a hadronic calorimeter and a muon identification system. The detector is able to distinguish interactions of all three neutrino flavours, which allows probing the physics of heavy flavour production at the LHC in the very forward region. This region is of particular interest for future circular colliders and for very high energy astrophysical neutrino experiments. The detector is also able to search for the scattering of Feebly Interacting Particles. In its first phase, the detector is ready to operate throughout LHC Run 3 and collect a total of 250 fb−1.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for an exotic decay of the Higgs boson into a Z boson and a pseudoscalar particle in proton-proton collisions at s=13TeV
, Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics, Vol: 852, ISSN: 0370-2693A search for an exotic decay of the Higgs boson to a Z boson and a light pseudoscalar particle (a), decaying to a pair of leptons and a pair of photons, respectively, is presented. The search is based on proton-proton collision data at a center-of-mass energy of s=13TeV, collected with the CMS detector at the LHC and corresponding to an integrated luminosity of 138fb−1. The analysis probes pseudoscalar masses ma between 1 and 30 GeV, leading to two pairs of well-isolated leptons and photons. Upper limits at 95% confidence level are set on the Higgs boson production cross section times its branching fraction to two leptons and two photons. The observed (expected) limits are in the range of 1.1–17.8 (1.7–17.9) fb within the probed ma interval. An excess of data above the expected standard model background with a local (global) significance of 2.6 (1.3) standard deviations is observed for a mass hypothesis of ma=3GeV. Limits on models involving axion-like particles, formulated as an effective field theory, are also reported.
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Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Search for Bc+→π+μ+μ- decays and measurement of the branching fraction ratio B(Bc+→ψ(2S)π+)/B(Bc+→J/ψπ+)
, European Physical Journal C, Vol: 84, ISSN: 1434-6044The first search for nonresonant Bc+→π+μ+μ- decays is reported. The analysis uses proton–proton collision data collected with the LHCb detector between 2011 and 2018, corresponding to an integrated luminosity of 9fb-1. No evidence for an excess of signal events over background is observed and an upper limit is set on the branching fraction ratio B(Bc+→π+μ+μ-)/B(Bc+→J/ψπ+)<2.1×10-4 at 90% confidence level. Additionally, an updated measurement of the ratio of the Bc+→ψ(2S)π+ and Bc+→J/ψπ+ branching fractions is reported. The ratio B(Bc+→ψ(2S)π+)/B(Bc+→J/ψπ+) is measured to be 0.254±0.018±0.003±0.005, where the first uncertainty is statistical, the second systematic, and the third is due to the uncertainties on the branching fractions of the leptonic J/ψ and ψ(2S) decays. This measurement is the most precise to date and is consistent with previous LHCb results.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Study of CP violation in B<sup>0</sup>→ DK<sup>⋆</sup>(892)<sup>0</sup> decays with D → Kπ(ππ), ππ(ππ), and KK final states
, Journal of High Energy Physics, Vol: 2024A measurement of CP-violating observables associated with the interference of B0→ D0K⋆(892)0 and B0→D¯0K⋆8920 decay amplitudes is performed in the D0→ K∓π±(π+π−), D0→ π+π−(π+π−), and D0→ K+K− final states using data collected by the LHCb experiment corresponding to an integrated luminosity of 9 fb−1. CP-violating observables related to the interference of Bs0→D0K¯⋆8920 and Bs0→D¯0K¯⋆8920 are also measured, but no evidence for interference is found. The B0 observables are used to constrain the parameter space of the CKM angle γ and the hadronic parameters rB0DK⋆ and δB0DK⋆ with inputs from other measurements. In a combined analysis, these measurements allow for four solutions in the parameter space, only one of which is consistent with the world average.
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Journal articleAbe K, Bronner C, Hayato Y, et al., 2024,
Solar neutrino measurements using the full data period of Super-Kamiokande-IV
, Physical Review D, Vol: 109, ISSN: 2470-0010An analysis of solar neutrino data from the fourth phase of Super-Kamiokande (SK-IV) from October 2008 to May 2018 is performed and the results are presented. The observation time of the dataset of SK-IV corresponds to 2970 days and the total live time for all four phases is 5805 days. For more precise solar neutrino measurements, several improvements are applied in this analysis: lowering the data acquisition threshold in May 2015, further reduction of the spallation background using neutron clustering events, precise energy reconstruction considering the time variation of the PMT gain. The observed number of solar neutrino events in 3.49-19.49 MeV electron kinetic energy region during SK-IV is 65,443-388+390(stat.)±925(syst.) events. Corresponding B8 solar neutrino flux is (2.314±0.014(stat.)±0.040(syst.))×106 cm-2 s-1, assuming a pure electron-neutrino flavor component without neutrino oscillations. The flux combined with all SK phases up to SK-IV is (2.336±0.011(stat.)±0.043(syst.))×106 cm-2 s-1. Based on the neutrino oscillation analysis from all solar experiments, including the SK 5805 days dataset, the best-fit neutrino oscillation parameters are sin2θ12,solar=0.306±0.013 and Δm21,solar2=(6.10-0.81+0.95)×10-5 eV2, with a deviation of about 1.5σ from the Δm212 parameter obtained by KamLAND. The best-fit neutrino oscillation parameters obtained from all solar experiments and KamLAND are sin2θ12,global=0.307±0.012 and Δm21,global2=(7.50-0.18+0.19)×10-5 eV2.
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Journal articleCampbell JM, Diefenthaler M, Hobbs TJ, et al., 2024,
Event generators for high-energy physics experiments
, SciPost Physics, Vol: 16We provide an overview of the status of Monte-Carlo event generators for high-energy particle physics. Guided by the experimental needs and requirements, we highlight areas of active development, and opportunities for future improvements. Particular emphasis is given to physics models and algorithms that are employed across a variety of experiments. These common themes in event generator development lead to a more comprehensive understanding of physics at the highest energies and intensities, and allow models to be tested against a wealth of data that have been accumulated over the past decades. A cohesive approach to event generator development will allow these models to be further improved and systematic uncertainties to be reduced, directly contributing to future experimental success. Event generators are part of a much larger ecosystem of computational tools. They typically involve a number of unknown model parameters that must be tuned to experimental data, while maintaining the integrity of the underlying physics models. Making both these data, and the analyses with which they have been obtained accessible to future users is an essential aspect of open science and data preservation. It ensures the consistency of physics models across a variety of experiments.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Measurement of the branching fraction of B<sup>0</sup>→ J/ψπ<sup>0</sup> decays
, Journal of High Energy Physics, Vol: 2024The ratio of branching fractions between B0 → J/ψπ0 and B+ → J/ψK*+ decays is measured with proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The measured value is (Formula presented.) where the first uncertainty is statistical and the second is systematic. The branching fraction for B0 → J/ψπ0 decays is determined using the branching fraction of the normalisation channel, resulting in (Formula presented.) where the last uncertainty corresponds to that of the external input. This result is consistent with the current world average value and competitive with the most precise single measurement to date.
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Journal articleCMS Collaboration, Hayrapetyan A, Tumasyan A, et al., 2024,
Search for exotic decays of the Higgs boson to a pair of pseudoscalars in the μμbb and ττbb final states
, European Physical Journal C: Particles and Fields, Vol: 84, ISSN: 1434-6052A search for exotic decays of the Higgs boson (H) with a mass of 125GeV to a pair of light pseudoscalars a1 is performed in final states where one pseudoscalar decays to two b quarks and the other to a pair of muons or τ leptons. A data sample of proton-proton collisions at s=13TeV corresponding to an integrated luminosity of 138fb-1 recorded with the CMS detector is analyzed. No statistically significant excess is observed over the standard model backgrounds. Upper limits are set at 95% confidence level (CL) on the Higgs boson branching fraction to μμbb and to ττbb, via a pair of a1s. The limits depend on the pseudoscalar mass ma1 and are observed to be in the range (0.17-3.3) ×10-4 and (1.7-7.7) ×10-2 in the μμbb and ττbb final states, respectively. In the framework of models with two Higgs doublets and a complex scalar singlet (2HDM+S), the results of the two final states are combined to determine upper limits on the branching fraction B(H→a1a1→ℓℓbb) at 95% CL, with ℓ being a muon or a τ lepton. For different types of 2HDM+S, upper bounds on the branching fraction B(H→a1a1) are extracted from the combination of the two channels. In most of the Type II 2HDM+S parameter space, B(H→a1a1) values above 0.23 are excluded at 95% CL for ma1 values between 15 and 60GeV.
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Journal articlePec V, Kudryavtsev VA, Araujo HM, et al., 2024,
Muon-induced background in a next-generation dark matter experiment based on liquid xenon
, European Physical Journal C: Particles and Fields, Vol: 84, ISSN: 1124-1861Muon-induced neutrons can lead to potentially irreducible backgrounds in rare event search experiments. We have investigated the implication of laboratory depth on the muon-induced background in a future dark matter experiment capable of reaching the so-called neutrino floor. Our simulation study focused on a xenon-based detector with 70 tonnes of active mass, surrounded by additional veto systems plus a water shield. Two locations at the Boulby Underground Laboratory (UK) were analysed as examples: an experimental cavern in salt at a depth of 2850 m w. e. (similar to the location of the existing laboratory), and a deeper laboratory located in polyhalite rock at a depth of 3575 m w. e. Our results show that no cosmogenic background events are likely to survive standard analysis cuts for 10 years of operation at either location. The largest background component we identified comes from beta-delayed neutron emission from
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Journal articleMcGarrigle JM, Long KR, Prezado Y, 2024,
The FLASH effect-an evaluation of preclinical studies of ultra-high dose rate radiotherapy
, Frontiers in Oncology, Vol: 14, ISSN: 2234-943XFLASH radiotherapy (FLASH-RT) is a novel radiotherapy approach based on the use of ultra-high dose radiation to treat malignant cells. Although tumours can be reduced or eradicated using radiotherapy, toxicities induced by radiation can compromise healthy tissues. The FLASH effect is the observation that treatment delivered at an ultra-high dose rate is able to reduce adverse toxicities present at conventional dose rates. While this novel technique may provide a turning point for clinical practice, the exact mechanisms underlying the causes or influences of the FLASH effect are not fully understood. The study presented here uses data collected from 41 experimental investigations (published before March 2024) of the FLASH effect. Searchable databases were constructed to contain the outcomes of the various experiments in addition to values of beam parameters that may have a bearing on the FLASH effect. An in-depth review of the impact of the key beam parameters on the results of the experiments was carried out. Correlations between parameter values and experimental outcomes were studied. Pulse Dose Rate had positive correlations with almost all end points, suggesting viability of FLASH-RT as a new modality of radiotherapy. The collective results of this systematic review study suggest that beam parameter qualities from both FLASH and conventional radiotherapy can be valuable for tissue sparing and effective tumour treatment.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Prompt and nonprompt ψ(2<i>S</i>) production in <i>p</i>Pb collisions at √<i>s</i><sub>NN</sub>=8.16 TeV
, JOURNAL OF HIGH ENERGY PHYSICS, ISSN: 1029-8479 -
Journal articleDatta A, Mazumdar D, Banerjee S, et al., 2024,
Erratum to “Magnetic, magnetocaloric and critical behavior studies in Heusler compounds Co<inf>2-x</inf>Cr<inf>1+x</inf>Al” [J. Magn. Magn. Mater. 591 (2024) 171743] (Journal of Magnetism and Magnetic Materials (2024) 591, (S0304885324000337), (10.1016/j.jmmm.2024.171743))
, Journal of Magnetism and Magnetic Materials, Vol: 596, ISSN: 0304-8853In the original article (https://doi.org/10.1016/j.jmmm.2024.171743), the units of the parameters in Table 1, and the values of the parameters in Table 3 and Table 4 are difficult to understand for a reader. The actual form of Table 1, Table 3 and Table 4 are given below. [Table prsented]
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Journal articleAbratenko P, Alterkait O, Andrade Aldana D, et al., 2024,
First Measurement of η Meson Production in Neutrino Interactions on Argon with MicroBooNE.
, Phys Rev Lett, Vol: 132We present a measurement of η production from neutrino interactions on argon with the MicroBooNE detector. The modeling of resonant neutrino interactions on argon is a critical aspect of the neutrino oscillation physics program being carried out by the DUNE and Short Baseline Neutrino programs. η production in neutrino interactions provides a powerful new probe of resonant interactions, complementary to pion channels, and is particularly suited to the study of higher-order resonances beyond the Δ(1232). We measure a flux-integrated cross section for neutrino-induced η production on argon of 3.22±0.84(stat)±0.86(syst) 10^{-41} cm^{2}/nucleon. By demonstrating the successful reconstruction of the two photons resulting from η production, this analysis enables a novel calibration technique for electromagnetic showers in GeV accelerator neutrino experiments.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2024,
Observation of the B<inf>c</inf><sup>+</sup>→J/ψπ<sup>+</sup>π<sup>0</sup> decay
, Journal of High Energy Physics, Vol: 2024The first observation of the Bc+→J/ψπ+π0 decay is reported with high significance using proton-proton collision data, corresponding to an integrated luminosity of 9 fb−1, collected with the LHCb detector at centre-of-mass energies of 7, 8, and 13 TeV. The ratio of its branching fraction relative to the Bc+→J/ψπ+ channel is measured to be (Formula presented.) where the first uncertainty is statistical, the second systematic and the third related to imprecise knowledge of the branching fractions for B+ → J/ψK*+ and Bc+→J/ψπ+ decays, which are used to determine the π0 detection efficiency. The π+π0 mass spectrum is found to be consistent with the dominance of an intermediate ρ+ contribution in accordance with a model based on QCD factorisation.
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Journal articleChakrani J, Dolan S, Avanzini MB, et al., 2024,
Parametrized uncertainties in the spectral function model of neutrino charged-current quasielastic interactions for oscillation analyses
, Physical Review D, Vol: 109, ISSN: 2470-0010A substantial fraction of systematic uncertainties in neutrino oscillation experiments stem from the lack of precision in modeling the nuclear target in neutrino-nucleus interactions. Whilst this has driven significant progress in the development of improved nuclear models for neutrino scattering, it is crucial that the models used in neutrino data analyses be accompanied by parameters and associated uncertainties that allow the coverage of plausible nuclear physics. Based on constraints from electron scattering data, we propose such a set of parameters, which can be applied to nuclear shell models, and test their application to the Benhar et al. [Nucl. Phys. A579, 493 (1994)NUPABL0375-947410.1016/0375-9474(94)90920-2] spectral function model. The parametrization is validated through a series of maximum likelihood fits to cross section measurements made by the T2K and MINERvA experiments, which also permit an exploration of the power of near-detector data to provide constraints on the parameters in neutrino oscillation analyses.
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Journal articleWester T, Abe K, Bronner C, et al., 2024,
Atmospheric neutrino oscillation analysis with neutron tagging and an expanded fiducial volume in Super-Kamiokande I-V
, Physical Review D, Vol: 109, ISSN: 2470-0010We present a measurement of neutrino oscillation parameters with the Super-Kamiokande detector using atmospheric neutrinos from the complete pure-water SK I-V (April 1996-July 2020) dataset, including events from an expanded fiducial volume. The dataset corresponds to 6511.3 live days and an exposure of 484.2 kiloton-years. Measurements of the neutrino oscillation parameters Δm322, sin2θ23, sin2θ13, δCP, and the preference for the neutrino mass ordering are presented with atmospheric neutrino data alone, and with constraints on sin2θ13 from reactor neutrino experiments. Our analysis including constraints on sin2θ13 favors the normal mass ordering at the 92.3% level.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for supersymmetry in final states with disappearing tracks in proton-proton collisions at Formula Presented
, Physical Review D, Vol: 109, ISSN: 2470-0010A search is presented for charged, long-lived supersymmetric particles in final states with one or more disappearing tracks. The search is based on data from proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS detector at the CERN LHC between 2016 and 2018, corresponding to an integrated luminosity of Formula Presented. The search is performed over final states characterized by varying numbers of jets, Formula Presented-tagged jets, electrons, and muons. The length of signal-candidate tracks in the plane perpendicular to the beam axis is used to characterize the lifetimes of wino- and Higgsino-like charginos produced in the context of the minimal supersymmetric standard model. The Formula Presented energy loss of signal-candidate tracks is used to increase the sensitivity to charginos with a large mass and thus a small Lorentz boost. The observed results are found to be statistically consistent with the background-only hypothesis. Limits on the pair-production cross section of gluinos and squarks are presented in the framework of simplified models of supersymmetric particle production and decay, and for electroweakino production based on models of wino and Higgsino dark matter. The limits presented are the most stringent to date for scenarios with light third-generation squarks and a wino- or Higgsino-like dark matter candidate capable of explaining the observed dark matter relic density.
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Journal articleAcar B, Adamov G, Adloff C, et al., 2024,
Timing performance of the CMS High Granularity Calorimeter prototype
, Journal of Instrumentation, Vol: 19This paper describes the experience with the calibration, reconstruction and evaluation of the timing capabilities of the CMS HGCAL prototype in the beam tests in 2018. The calibration procedure includes multiple steps and corrections ranging from tens of nanoseconds to a few hundred picoseconds. The timing performance is studied using signals from positron beam particles with energies between 20 GeV and 300 GeV. The performance is studied as a function of particle energy against an external timing reference as well as standalone by comparing the two different halves of the prototype. The timing resolution is found to be 60 ps for single-channel measurements and better than 20 ps for full showers at the highest energies, setting excellent perspectives for the HGCAL calorimeter performance at the HL-LHC.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2024,
Search for flavor changing neutral current interactions of the top quark in final states with a photon and additional jets in proton-proton collisions at Formula Presented
, Physical Review D, Vol: 109, ISSN: 2470-0010A search for the production of a top quark in association with a photon and additional jets via flavor changing neutral current interactions is presented. The analysis uses proton-proton collision data recorded by the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of Formula Presented. The search is performed by looking for processes where a single top quark is produced in association with a photon, or a pair of top quarks where one of the top quarks decays into a photon and an up or charm quark. Events with an electron or a muon, a photon, one or more jets, and missing transverse momentum are selected. Multivariate analysis techniques are used to discriminate signal and standard model background processes. No significant deviation is observed over the predicted background. Observed (expected) upper limits are set on the branching fractions of top quark decays: Formula Presented (Formula Presented) and Formula Presented (Formula Presented) at 95% confidence level, assuming a single nonzero coupling at a time. The obtained limit for Formula Presented is similar to the current best limit, while the limit for Formula Presented is significantly tighter than previous results.
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Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2024,
Measurement of Ξ<sub>c</sub><SUP>+</SUP> production in <i>p</i>Pb collisions at √<i>s<sub>NN</sub></i>=8.16 TeV at LHCb
, PHYSICAL REVIEW C, Vol: 109, ISSN: 2469-9985 -
Journal articleHoenig D, Thielemann F, Karpa L, et al., 2024,
Trapping Ion Coulomb Crystals in an Optical Lattice.
, Phys Rev Lett, Vol: 132We report the optical trapping of multiple ions localized at individual lattice sites of a one-dimensional optical lattice. We observe a fivefold increased range of axial dc-electric field strength for which ions can be optically trapped with high probability and an increase of the axial eigenfrequency by 2 orders of magnitude compared to an optical dipole trap without interference but of similar intensity. Our findings motivate an alternative pathway to extend arrays of trapped ions in size and dimension, enabling quantum simulations with particles interacting at long range.
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