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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
Measurements of the Higgs boson production cross section in the four-lepton final state in proton-proton collisions at √<i>s</i>=13<i>.</i>6 TeV
, JOURNAL OF HIGH ENERGY PHYSICS -
Journal articleAaij R, Abdelmotteleb ASW, Beteta CA, et al., 2025,
Measurement of <i>CP</i> asymmetries in Λ<i><sub>b</sub></i><SUP>0</SUP> → <i>ph</i><SUP>-</SUP> decays
, PHYSICAL REVIEW D, Vol: 111, ISSN: 2470-0010- Cite
- Citations: 3
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Reweighting simulated events using machine-learning techniques in the CMS experiment
, EUROPEAN PHYSICAL JOURNAL C, Vol: 85, ISSN: 1434-6044 -
Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
Measurement of the multiplicity dependence of Γ production ratios in <i>pp</i> collisions at √<i>s</i>=13 Tev
, JOURNAL OF HIGH ENERGY PHYSICS -
Journal articleAad G, Aakvaag E, Abbott B, et al., 2025,
Test of lepton flavour universality in W-boson decays into electrons and τ-leptons using pp collisions at s = 13 TeV with the ATLAS detector
, Journal of High Energy Physics, Vol: 2025A measurement of the ratio of the branching fractions, R<inf>τ/e</inf> = B(W → τν)/B(W → eν), is performed using a sample of W bosons originating from top-quark decays to final states containing τ-leptons or electrons. This measurement uses pp collisions at s = 13 TeV, collected by the ATLAS experiment at the Large Hadron Collider during Run 2, corresponding to an integrated luminosity of 140 fb<sup>−1</sup>. The W → τν<inf>τ</inf> (with τ → eν<inf>e</inf>ν<inf>τ</inf>) and W → eν<inf>e</inf> decays are distinguished using the differences in the impact parameter distributions and transverse momentum spectra of the electrons. The measured ratio of branching fractions R<inf>τ/e</inf> = 0.975 ± 0.012 (stat.) ± 0.020 (syst.), is consistent with the Standard Model assumption of lepton flavour universality in W-boson decays.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
Search for D0 meson decays to π+π-e+e- and K+K-e+e- final states
, Physical Review D, Vol: 111, ISSN: 2470-0010A search for D0 meson decays to the π+π-e+e- and K+K-e+e- final states is reported using a sample of proton-proton collisions collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6 fb-1. The decay D0→π+π-e+e- is observed for the first time when requiring that the two electrons are consistent with coming from the decay of a φ or ρ0/ω meson. The corresponding branching fractions are measured relative to the D0→K-π-[e+e-]ρ0/ω decay, where the two electrons are consistent with coming from the decay of a ρ0 or ω meson. No evidence is found for the D0→K+K-e+e- decay and world-best limits are set on its branching fraction. The results are compared to, and found to be consistent with, the branching fractions of the D0→π+π-μ+μ- and D0→K+K-μ+μ- decays recently measured by LHCb and confirm lepton universality at the current precision.
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Journal articleZwalinski L, Zou W, Zormpa O, et al., 2025,
Reconstruction and identification of pairs of collimated τ-leptons decaying hadronically using s=13 TeV pp collision data with the ATLAS detector
, European Physical Journal C, Vol: 85, ISSN: 1434-6044This paper describes an algorithm for reconstructing and identifying a highly collimated hadronically decaying τ-lepton pair with low transverse momentum. When two τ-leptons are highly collimated, their visible decay products might overlap, degrading the reconstruction performance for each of the τ-leptons. A dedicated treatment attempting to tag the τ-lepton pair as a single object is required. The reconstruction algorithm is based on a large radius jet and its associated two leading subjets, and the identification uses a boosted decision tree to discriminate between signatures from τ+τ- systems and those arising from QCD jets. The efficiency of the identification algorithm is measured in Zγ events using proton–proton collision data at s=13 TeV collected by the ATLAS experiment at the Large Hadron Collider between 2015 and 2018, corresponding to an integrated luminosity of 139fb-1. The resulting data-to-simulation scale factors are close to unity with uncertainties ranging from 26 to 37%.
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Journal articleZwalinski L, Zou W, Zormpa O, et al., 2025,
Search for tt¯H/A→tt¯tt¯ production in proton–proton collisions at s=13 TeV with the ATLAS detector
, European Physical Journal C, Vol: 85, ISSN: 1434-6044A search is presented for a heavy scalar (H) or pseudo-scalar (A) predicted by the two-Higgs-doublet models, where the H/A is produced in association with a top-quark pair (tt¯H/A), and with the H/A decaying into a tt¯ pair. The full LHC Run 2 proton–proton collision data collected by the ATLAS experiment is used, corresponding to an integrated luminosity of 139fb-1. Events are selected requiring exactly one or two opposite-charge electrons or muons. Data-driven corrections are applied to improve the modelling of the tt¯+jets background in the regime with high jet and b-jet multiplicities. These include a novel multi-dimensional kinematic reweighting based on a neural network trained using data and simulations. An H/A-mass parameterised graph neural network is trained to optimise the signal-to-background discrimination. In combination with the previous search performed by the ATLAS Collaboration in the multilepton final state, the observed upper limits on the tt¯H/A→tt¯tt¯ production cross-section at 95% confidence level range between 14 fb and 5.0 fb for an H/A with mass between 400 GeV and 1000 GeV, respectively. Assuming that both the H and A contribute to the tt¯tt¯ cross-section, tanβ values below 1.7 or 0.7 are excluded for a mass of 400 GeV or 1000 GeV, respectively. The results are also used to constrain a model predicting the pair production of a colour-octet scalar, with the scalar decaying into a tt¯ pair.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Angular analysis of the B<SUP>0</SUP> → K*(892)<SUP>0</SUP>μ<SUP>+</SUP> μ<SUP>-</SUP> decay in proton-proton collisions at √<i>s</i>=13 TeV
, PHYSICS LETTERS B, Vol: 864, ISSN: 0370-2693- Cite
- Citations: 1
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Journal articleAbratenko P, Alterkait O, Andrade Aldana D, et al., 2025,
First Double-Differential Cross Section Measurement of Neutral-Current π^{0} Production in Neutrino-Argon Scattering in the MicroBooNE Detector.
, Phys Rev Lett, Vol: 134We report the first double-differential cross section measurement of neutral-current neutral pion (NCπ^{0}) production in neutrino-argon scattering, as well as single-differential measurements of the same channel in terms of final states with and without protons. The kinematic variables of interest for these measurements are the π^{0} momentum and the π^{0} scattering angle with respect to the neutrino beam. A total of 4971 candidate NCπ^{0} events fully contained within the MicroBooNE detector are selected using data collected at a mean neutrino energy of ∼0.8 GeV from 6.4×10^{20} protons on target from the Booster Neutrino Beam at the Fermi National Accelerator Laboratory. After extensive data-driven model validation to ensure unbiased unfolding, the Wiener-singular-value-decomposition method is used to extract nominal flux-averaged cross sections. The results are compared to predictions from commonly used neutrino event generators, which tend to overpredict the measured NCπ^{0} cross section, especially in the 0.2-0.5 GeV/c π^{0} momentum range and at forward scattering angles. Events with at least one proton present in the final state are also underestimated. This data will help improve the modeling of NCπ^{0} production, which represents a major background in measurements of charge-parity violation in the neutrino sector and in searches for new physics beyond the standard model.
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Journal articleAad G, Aakvaag E, Abbott B, et al., 2025,
ATLAS searches for additional scalars and exotic Higgs boson decays with the LHC Run 2 dataset
, Physics Reports, Vol: 1116, Pages: 184-260, ISSN: 0370-1573This report reviews the published results of searches for possible additional scalar particles and exotic decays of the Higgs boson performed by the ATLAS Collaboration using up to 140 fb<sup>−1</sup> of 13 TeV proton–proton collision data collected during Run 2 of the Large Hadron Collider. Key results are examined, and observed excesses, while never statistically compelling, are noted. Constraints are placed on parameters of several models which extend the Standard Model, for example by adding one or more singlet or doublet fields, or offering exotic Higgs boson decay channels. Summaries of new searches as well as extensions of previous searches are discussed. These new results have a wider reach or attain stronger exclusion limits. New experimental techniques that were developed for these searches are highlighted. Search channels which have not yet been examined are also listed, as these provide insight into possible future areas of exploration.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Overview of high-density QCD studies with the CMS experiment at the LHC
, PHYSICS REPORTS-REVIEW SECTION OF PHYSICS LETTERS, Vol: 1115, Pages: 219-367, ISSN: 0370-1573- Cite
- Citations: 6
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Measurement of the inclusive WZ production cross section in pp collisions at √<i>s</i>=13<i>.</i>6 TeV
, JOURNAL OF HIGH ENERGY PHYSICS -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for heavy long-lived charged particles with large ionization energy loss in proton-proton collisions at √<i>s</i>=13 TeV
, JOURNAL OF HIGH ENERGY PHYSICS- Cite
- Citations: 1
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Journal articleAad G, Aakvaag E, Abbott B, et al., 2025,
Observation of tt[over ¯] Production in Pb+Pb Collisions at sqrt[s_{NN}]=5.02 TeV with the ATLAS Detector.
, Phys Rev Lett, Vol: 134Top-quark pair production is observed in lead-lead (Pb+Pb) collisions at sqrt[s_{NN}]=5.02 TeV at the Large Hadron Collider with the ATLAS detector. The data sample was recorded in 2015 and 2018, amounting to an integrated luminosity of 1.9 nb^{-1}. Events with exactly one electron and one muon and at least two jets are selected. Top-quark pair production is measured with an observed (expected) significance of 5.0 (4.1) standard deviations. The measured top-quark pair production cross section is σ_{tt[over ¯]}=3.6 _{-0.9}^{+1.0}(stat) _{-0.5}^{+0.8}(syst) μb, with a total relative uncertainty of 31%, and is consistent with theoretical predictions using a range of different nuclear parton distribution functions. The observation of this process consolidates the evidence of the existence of all quark flavors in the preequilibrium stage of the quark-gluon plasma at very high energy densities, similar to the conditions present in the early Universe.
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Journal articleSchueler J, Araujo HM, Balashov SN, et al., 2025,
Transforming a rare event search into a not-so-rare event search in real-time with deep learning-based object detection
, PHYSICAL REVIEW D, Vol: 111, ISSN: 2470-0010 -
Journal articleAad G, Aakvaag E, Abbott B, et al., 2025,
Search for charged Higgs bosons produced in top-quark decays or in association with top quarks and decaying via <i>H</i><SUP>±</SUP> → ι<SUP>±</SUP> ν<sub>τ</sub> in 13 TeV <i>pp</i> collisions with the ATLAS detector
, PHYSICAL REVIEW D, Vol: 111, ISSN: 2470-0010- Cite
- Citations: 1
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Energy-scaling behavior of intrinsic transverse-momentum parameters in Drell-Yan simulation
, PHYSICAL REVIEW D, Vol: 111, ISSN: 2470-0010 -
Journal articleAbdalla A, Abe M, Abend S, et al., 2025,
Terrestrial Very-Long-Baseline Atom Interferometry: summary of the second workshop
, EPJ Quantum Technology, Vol: 12, ISSN: 2196-0763This summary of the second Terrestrial Very-Long-Baseline Atom Interferometry (TVLBAI) Workshop provides a comprehensive overview of our meeting held in London in April 2024 (Second Terrestrial Very-Long-Baseline Atom Interferometry Workshop, Imperial College, April 2024), building on the initial discussions during the inaugural workshop held at CERN in March 2023 (First Terrestrial Very-Long-Baseline Atom Interferometry Workshop, CERN, March 2023). Like the summary of the first workshop (Abend et al. in AVS Quantum Sci. 6:024701, 2024), this document records a critical milestone for the international atom interferometry community. It documents our concerted efforts to evaluate progress, address emerging challenges, and refine strategic directions for future large-scale atom interferometry projects. Our commitment to collaboration is manifested by the integration of diverse expertise and the coordination of international resources, all aimed at advancing the frontiers of atom interferometry physics and technology, as set out in a Memorandum of Understanding signed by over 50 institutions (Memorandum of Understanding for the Terrestrial Very Long Baseline Atom Interferometer Study).
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for Fractionally Charged Particles in Proton-Proton Collisions at √<i>s</i>=13 TeV
, PHYSICAL REVIEW LETTERS, Vol: 134, ISSN: 0031-9007 -
Journal articleAad G, Aakvaag E, Abbott B, et al., 2025,
Search for the jet-induced diffusion wake in the quark-gluon plasma via measurements of jet-track correlations in photon-jet events in (Formula presented) collisions at (Formula presented) with the ATLAS detector
, Physical Review C, Vol: 111, ISSN: 2469-9985This paper presents a measurement of jet-track correlations in photon-jet events, using 1.72 (Formula presented) of (Formula presented) data at (Formula presented) recorded with the ATLAS detector at the LHC. Events with energetic photon-jet pairs are selected, where the photon and jet are approximately back-to-back in azimuth. The angular correlation between jets and charged-particle tracks with transverse momentum ((Formula presented)) in the range 0.5-2.0 GeV in the hemisphere opposite to the jet, (Formula presented), is measured as a function of their relative pseudorapidity difference, (Formula presented). In central (Formula presented) collisions, these correlations are predicted to be sensitive to the diffusion wake in the quark-gluon plasma resulting from the lost energy of high-(Formula presented) partons traversing the plasma, with a characteristic modification as a function of (Formula presented). The correlations are examined with different selections on the jet-to-photon (Formula presented) ratio to select events with different degrees of energy loss. No diffusion wake signal is observed within the current sensitivity and upper limits at 95% confidence level on the diffusion wake amplitude are reported.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Measurement of the inclusive tt¯ cross section in final states with at least one lepton and additional jets with 302 pb−1 of pp collisions at s = 5.02 TeV
, Journal of High Energy Physics, Vol: 2025A measurement of the top quark pair (tt¯) production cross section in proton-proton collisions at a centre-of-mass energy of 5.02 TeV is presented. The data were collected at the LHC in autumn 2017, in dedicated runs with low-energy and low-intensity conditions with respect to the default configuration, and correspond to an integrated luminosity of 302 pb<sup>−1</sup>. The measurement is performed using events with one electron or muon, and multiple jets, at least one of them being identified as originating from a b quark (b tagged). Events are classified based on the number of all reconstructed jets and of b-tagged jets. Multivariate analysis techniques are used to enhance the separation between the signal and backgrounds. The measured cross section is 62.5±1.6stat−2.5+2.6syst±1.2lumi pb. A combination with the result in the dilepton channel based on the same data set yields a value of 62.3 ± 1.5 (stat) ± 2.4 (syst) ± 1.2 (lumi) pb, to be compared with the standard model prediction of 69.5−3.7+3.5 pb at next-to-next-to-leading order in perturbative quantum chromodynamics.
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Journal articleZwalinski L, Zou W, Zormpa O, et al., 2025,
Measurement of the Lund jet plane in hadronic decays of top quarks and W bosons with the ATLAS detector
, European Physical Journal C, Vol: 85, ISSN: 1434-6044The Lund jet plane (LJP) is measured for the first time in tt¯ events, using 140 fb-1 of s=13 TeV pp collision data collected with the ATLAS detector at the LHC. The LJP is a two-dimensional observable of the sub-structure of hadronic jets that acts as a proxy for the kinematics of parton showers and hadron formation. The observable is constructed from charged particles and is measured for R=1.0 anti-kt jets with transverse momentum above 350 GeV containing the full decay products of either a top quark or a daughter W boson. The other top quark in the event is identified from its decay into a b-quark, an electron or a muon and a neutrino. The measurement is corrected for detector effects and compared with a range of Monte Carlo predictions sensitive to different aspects of the hadronic decays of the heavy particles. In the W-boson-initiated jets, all the predictions are incompatible with the measurement. In the top quark initiated jets, disagreement with all predictions is observed in smaller subregions of the plane, and with a subset of the predictions across the fiducial plane. The measurement could be used to improve the tuning of Monte Carlo generators, for better modelling of hadronic decays of heavy quarks and bosons, or to improve the performance of jet taggers.
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Journal articleAalbers J, Abe K, Adrover M, et al., 2025,
Neutrinoless double beta decay sensitivity of the XLZD rare event observatory
, Journal of Physics G: Nuclear and Particle Physics, Vol: 52, ISSN: 0954-3899The XLZD collaboration is developing a two-phase xenon time projection chamber with an active mass of 60–80 t capable of probing the remaining weakly interacting massive particle-nucleon interaction parameter space down to the so-called neutrino fog. In this work we show that, based on the performance of currently operating detectors using the same technology and a realistic reduction of radioactivity in detector materials, such an experiment will also be able to competitively search for neutrinoless double beta decay in 136Xe using a natural-abundance xenon target. XLZD can reach a 3σ discovery potential half-life of 5.7 × 1027 years (and a 90% CL exclusion of 1.3 × 1028 years) with 10 years of data taking, corresponding to a Majorana mass range of 7.3–31.3 meV (4.8–20.5 meV). XLZD will thus exclude the inverted neutrino mass ordering parameter space and will start to probe the normal ordering region for most of the nuclear matrix elements commonly considered by the community.
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Journal article, 2025,
Review of searches for vector-like quarks, vector-like leptons, and heavy neutral leptons in proton–proton collisions at √s=13 TeV at the CMS experiment
, Physics Reports, Vol: 1115, Pages: 570-677, ISSN: 0370-1573 -
Journal article, 2025,
Searches for Higgs boson production through decays of heavy resonances
, Physics Reports, Vol: 1115, Pages: 368-447, ISSN: 0370-1573 -
Journal article, 2025,
Enriching the physics program of the CMS experiment via data scouting and data parking
, Physics Reports, Vol: 1115, Pages: 678-772, ISSN: 0370-1573 -
Journal article, 2025,
Review of top quark mass measurements in CMS
, Physics Reports, Vol: 1115, Pages: 116-218, ISSN: 0370-1573 -
Journal article, 2025,
Stairway to discovery: A report on the CMS programme of cross section measurements from millibarns to femtobarns
, Physics Reports, Vol: 1115, Pages: 3-115, ISSN: 0370-1573 -
Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Proton reconstruction with the TOTEM Roman pot detectors for high-β* LHC data
, JOURNAL OF INSTRUMENTATION, Vol: 20
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