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Conference paperAbarr Q, Allison P, Alvarez-Muñiz J, et al., 2025,
Searching for Ultrahigh Energy Neutrinos with PUEO
PUEO, the Payload for Ultrahigh Energy Observations, is a long duration balloon-borne experiment with the primary science goal of detecting the impulsive Askaryan emission from ultrahigh energy (UHE, >1 EeV) neutrinos interacting in the ice sheet of Antarctica. The ultrahigh energy neutrino flux is yet to be detected, and so a successful measurement by PUEO will give us information about the where and how these neutrinos are produced; this may be through a process called the GZK effect when ultrahigh energy cosmic rays interact with the cosmic microwave background, or it may be directly within the environment of cosmic ray accelerators. In order to detect radio Askaryan emission, PUEO consists of a broadband interferometric radio detector of 96 antennas which point down at the ice. Additionally, it has a drop-down low-frequency subsystem which will deploy after launch. This improves PUEO’s ability to detect tau neutrinos and charged cosmic rays, which can both produce geomagnetic air shower emission. This contribution will outline PUEO’s science case, present its expected sensitivity, and share status updates from our preparation to launch PUEO from McMurdo Station, Antarctica in December 2025.
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Conference paperAli S, Besson DZ, Alden N, et al., 2025,
Study of an Isolated Double-pulse Cosmic Ray Candidate Recorded with the Askaryan Radio Array
The radio-frequency emissions produced by particle showers on Earth, resulting from cosmic rays (CRs) and ultra-high energy neutrinos (UHE-ν) originating from astrophysical sources share significant similarities, enabling radio detectors initially designed for UHE-ν searches to also study CRs. The Askaryan Radio Array (ARA), an experiment currently operating within the ice at the South Pole, is primarily designed to detect UHE-νs. To date, ARA has deployed five stations, with each station equipped with antennas installed at depths up to 200 meters in the ice. Data recorded by ARA Station-2 (A2) suggest a potential CR origin for a subset of events identified in a UHEν search. This subset includes a double-pulse event potentially from a downward propagating CR-induced air shower, with in-air geomagnetic emission followed by in-ice Askaryan emission producing the two pulses. A detailed investigation of this CR candidate event using comprehensive simulations has been conducted with the goal of identifying the parameters of a CR-induced air shower that best match the experimentally observed quantities. We simulate predicted CR signals in ARA by combining an impacting CR shower simulation framework (FAERIE) with a realistic detector simulation (AraSim). We determine the event topology based on the vertex reconstruction of both the putative geomagnetic and Askaryan signals. After inferring the event geometry, we show that the simulation matches the observed time structure of the event (channel-by-channel relative signal arrival times) for the recorded event.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
General search for supersymmetric particles in scenarios with compressed mass spectra using proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>TeV</mml:mi> </mml:math>
, Physical Review D, Vol: 112, ISSN: 2470-0010<jats:p> A general search is presented for supersymmetric particles (sparticles) in scenarios featuring compressed mass spectra using proton-proton collisions at a center-of-mass energy of 13 TeV, recorded with the CMS detector at the LHC. The analyzed data sample corresponds to an integrated luminosity of <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mn>138</a:mn> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:msup> <a:mi>fb</a:mi> <a:mrow> <a:mo>−</a:mo> <a:mn>1</a:mn> </a:mrow> </a:msup> </a:math> . A wide range of potential sparticle signatures are targeted, including pair production of electroweakinos, sleptons, and top squarks. The search focuses on events with a high transverse momentum system from initial-state-radiation jets recoiling against a potential sparticle system with significant missing transverse momentum. Events are categorized based on their lepton multiplicity, jet multiplicity, number of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mi>b</c:mi> </c:math> -tagged jets, and kinematic variables sensitive to the sparticle masses and mass splittings. The sensitivity extends to higher parent sparticle masses than previously probed at the LHC for production of pairs of electroweakinos, sleptons, and top squarks with mass spectra featuring small mass splittings (compressed mass spectra). The observed results demonstrate agreemen
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2025,
Search for charged lepton flavor violating <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Z</mml:mi> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msup> <mml:mi>Z</mml:mi> <mml:mo>′</mml:mo> </mml:msup> </mml:math> boson decays in proton-proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mtext> </mml:mtext> <mml:mtext> </mml:mtext> <mml:mi>TeV</mml:mi> </mml:math>
, Physical Review D, Vol: 112, ISSN: 2470-0010<jats:p> A search for flavor violating decays of the <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>Z</a:mi> </a:math> boson to charged leptons is performed using data from proton-proton collisions at <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msqrt> <c:mi>s</c:mi> </c:msqrt> <c:mo>=</c:mo> <c:mn>13</c:mn> <c:mtext> </c:mtext> <c:mtext> </c:mtext> <c:mi>TeV</c:mi> </c:math> collected with the CMS detector at the LHC, corresponding to an integrated luminosity of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mn>138</e:mn> <e:mtext> </e:mtext> <e:mtext> </e:mtext> <e:msup> <e:mi>fb</e:mi> <e:mrow> <e:mo>−</e:mo> <e:mn>1</e:mn> </e:mrow> </e:msup> </e:math> . Each of the decays <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mi>Z</g:mi> <g:mo stretchy="false">→</g:mo> <g:mi>e</g:mi>
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
Measurement of event shapes in minimum-bias events from proton-proton collisions at √s = 13 TeV
, Physical Review D, Vol: 112, ISSN: 2470-0010A measurement of event-shape variables is presented, using a data sample produced in a special run with approximately one inelastic proton-proton collision per bunch crossing. The data were collected with the CMS detector at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 64 μb<sup>−1</sup>. A number of observables related to the overall distribution of charged particles in the collisions are corrected for detector effects and compared with simulations. Inclusive event-shape distributions, as well as differential distributions of event shapes as functions of charged-particle multiplicity, are studied. None of the models investigated are able to satisfactorily describe the data. Moreover, there are significant features common amongst all generator setups studied, particularly showing data being more isotropic than any of the simulations. Multidimensional unfolded distributions are provided, along with their correlations.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for New Physics in Jet Multiplicity Patterns of Multilepton Events at sqrt[s]=13 TeV.
, Phys Rev Lett, Vol: 135A first search for beyond the standard model physics in jet multiplicity patterns of multilepton events is presented, using a data sample corresponding to an integrated luminosity of 138 fb^{-1} of 13 TeV proton-proton collisions recorded by the CMS detector at the LHC. The search uses observed jet multiplicity distributions in one-, two-, and four-lepton events to explore possible enhancements in jet production rate in three-lepton events with and without bottom quarks. The data are found to be consistent with the standard model expectation. The results are interpreted in terms of supersymmetric production of electroweak chargino-neutralino superpartners with cascade decays terminating in prompt hadronic R-parity violating interactions.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
Observation of Orbitally Excited B_{c}^{+} States.
, Phys Rev Lett, Vol: 135The observation of a wide peaking structure in the B_{c}^{+}γ mass spectrum is reported using proton-proton collision data collected by the LHCb detector at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9 fb^{-1}. The statistical significance over the background-only hypothesis exceeds seven standard deviations. The width of the observed structure is larger than the expectation from a single-peak hypothesis, and is well described by an effective minimal model consisting of two narrow peaks located at 6704.8±5.5±2.8±0.3 MeV/c^{2} and 6752.4±9.5±3.1±0.3 MeV/c^{2}. The uncertainty terms are statistical, systematic, and associated to the knowledge of the B_{c}^{+} mass, respectively. The measured peak locations are in line with theoretical predictions for lowest excited P-wave B_{c}^{+} states, marking the first observation of orbitally excited beauty-charm mesons and providing important insights into the internal dynamics of hadrons containing two heavy quarks.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Determination of the spin and parity of all-charm tetraquarks
, NATURE, Vol: 648, Pages: 58-+, ISSN: 0028-0836 -
Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
Search for the decay B0→ ϕϕ
, Journal of High Energy Physics, Vol: 2025A search for the decay B<sup>0</sup>→ ϕϕ is made using pp collision data collected with the LHCb detector at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb<sup>−1</sup>. No significant signal is observed, and an upper limit on the branching fraction of 1.3 (1.4) × 10<sup>−8</sup> at 90 (95)% confidence level is set. This result supersedes the previous LHCb study and improves the upper limit by a factor of two.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2025,
Identification of tau leptons using a convolutional neural network with domain adaptation
, Journal of Instrumentation, Vol: 20, Pages: P12032-P12032<jats:title>Abstract</jats:title> <jats:p> A tau lepton identification algorithm, <jats:sc>DeepTau</jats:sc> , based on convolutional neural network techniques, has been developed in the CMS experiment to discriminate reconstructed hadronic decays of tau leptons (τ <jats:sub>h</jats:sub> ) from quark or gluon jets and electrons and muons that are misreconstructed as τ <jats:sub>h</jats:sub> candidates. The latest version of this algorithm, v2.5, includes domain adaptation by backpropagation, a technique that reduces discrepancies between collision data and simulation in the region with the highest purity of genuine τ <jats:sub>h</jats:sub> candidates. Additionally, a refined training workflow improves classification performance with respect to the previous version of the algorithm, with a reduction of 30–50% in the probability for quark and gluon jets to be misidentified as τ <jats:sub>h</jats:sub> candidates for given reconstruction and identification efficiencies. This paper presents the novel improvements introduced in the <jats:sc>DeepTau</jats:sc> algorithm and evaluates its performance in LHC proton-proton collision data at √( <jats:italic>s</jats:italic> ) = 13 and 13.6 TeV collected in 2018 and 2022 with integrated luminosities of 60 and 35 fb <jats:sup>-1</jats:sup> , respectively. Techniques to calibrate the performance of the τ <jats:sub>h</jats:sub> identification algorithm in simulation with respect
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Journal articleZsoldos S, Zito M, Zimmerman ED, et al., 2025,
Testing T2K’s Bayesian constraints with priors in alternate parameterisations
, European Physical Journal C, Vol: 85, ISSN: 1434-6044Bayesian analysis results require a choice of prior distribution. In long-baseline neutrino oscillation physics, the usual parameterisation of the mixing matrix induces a prior that privileges certain neutrino mass and flavour state symmetries. Here we study the effect of privileging alternate symmetries on the results of the T2K experiment. We find that constraints on the level of CP violation (as given by the Jarlskog invariant) are robust under the choices of prior considered in the analysis. On the other hand, the degree of octant preference for the atmospheric angle depends on which symmetry has been privileged.
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Journal articleCollaboration TCMS, 2025,
Search for heavy pseudoscalar and scalar bosons decaying to a top quark pair in proton–proton collisions at <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mstyle/> <mml:mtext>TeV</mml:mtext> </mml:mrow> </mml:math>
, Reports on Progress in Physics, Vol: 88, Pages: 127801-127801, ISSN: 0034-4885<jats:title>Abstract</jats:title> <jats:p> A search for pseudoscalar or scalar bosons decaying to a top quark pair ( <jats:inline-formula> <jats:tex-math> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mrow> <mml:mtext>t</mml:mtext> </mml:mrow> <mml:mrow> <mml:mover> <mml:mtext>t</mml:mtext> <mml:mo stretchy="false">¯</mml:mo> </mml:mover> </mml:mrow> </mml:mrow> </mml:math> </jats:inline-formula> ) in final states with one or two charged leptons is presented. The analyzed proton–proton collision data was recorded at <jats:inline-formula> <jats:tex-math> </jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> <mml:mstyle scriptlevel="0"/> <mml:mtext>TeV</mml:mtext> </mml:mrow
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
Search for <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>γ</mml:mi> <mml:mi>H</mml:mi> </mml:math> production and constraints on the Yukawa couplings of light quarks to the Higgs boson
, Physical Review D, Vol: 112, ISSN: 2470-0010<jats:p> A search for <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>γ</a:mi> <a:mi>H</a:mi> </a:math> production is performed with data from the CMS experiment at the LHC corresponding to an integrated luminosity of <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:mn>138</c:mn> <c:mtext> </c:mtext> <c:mtext> </c:mtext> <c:msup> <c:mi>fb</c:mi> <c:mrow> <c:mo>−</c:mo> <c:mn>1</c:mn> </c:mrow> </c:msup> </c:math> at a proton-proton center-of-mass collision energy of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:mrow> <e:mn>13</e:mn> <e:mtext> </e:mtext> <e:mtext> </e:mtext> <e:mi>TeV</e:mi> </e:mrow> </e:math> . The analysis focuses on the topology of a boosted Higgs boson recoiling against a high-energy photon. The final states of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mi>H</g:mi> <g:mo stretchy="false">→</g:mo>
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
Study of charm mixing and CP violation with D0→ K±π∓π±π∓ decays
, Journal of High Energy Physics, Vol: 2025A study of charm mixing and CP violation in D<sup>0</sup> → K<sup>±</sup>π<sup>∓</sup>π<sup>±</sup>π<sup>∓</sup> decays is performed using data collected by the LHCb experiment in proton-proton collisions from 2015 to 2018, corresponding to an integrated luminosity of 6 fb<sup>−1</sup>. The ratio of promptly produced D<sup>0</sup> → K<sup>+</sup>π<sup>−</sup>π<sup>+</sup>π<sup>−</sup> to D<sup>0</sup> → K<sup>−</sup>π<sup>+</sup>π<sup>−</sup>π<sup>+</sup> decay rates is measured as a function of D<sup>0</sup> decay time, both inclusive over phase space and in bins of phase space. Taking external inputs for the D0−D¯0 mixing parameters x and y allows constraints to be obtained on the hadronic parameters of the charm decay. When combined with previous measurements from charm-threshold experiments and at LHCb, improved knowledge is obtained for these parameters, which is valuable for studies of the angle γ of the Unitarity Triangle. An alternative analysis is also performed, in which external inputs are taken for the hadronic parameters, and the mixing parameters are determined, including ∆x and ∆y, which are nonzero in the presence of CP violation. It is found that x=0.85−0.24+0.15%, y=0.21−0.27+0.29%, ∆x = (−0.02 ± 0.04) % and Δy=0.02−0.03+0.04%. These results are consistent with previous measurements and the hypothesis of CP conservation.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
Measurement of the B0→ ρ(770)0γ branching fraction
, Journal of High Energy Physics, Vol: 2025The ratio between the branching fractions of the B<sup>0</sup> → ρ(770)<sup>0</sup>γ and B<sup>0</sup> → K<sup>*</sup>(892)<sup>0</sup>γ decays is measured with proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb<sup>−1</sup>. The measured value is (Formula presented.) where the first uncertainty is statistical and the second systematic. The branching fraction for B<sup>0</sup>→ ρ(770)<sup>0</sup>γ decays is hence obtained as (Formula presented.) where the last uncertainty is due to the branching fraction of the normalisation mode. This result assumes that both the ρ(770)<sup>0</sup> and K<sup>*</sup>(892)<sup>0</sup> decays saturate the dihadron mass spectra considered in the analysis. It is consistent with the current world-average value and by far the most precise measurement to date.
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Journal articleBenedikt M, Zimmermann F, Auchmann B, et al., 2025,
Future Circular Collider Feasibility Study Report: Volume 1 Physics, Experiments, Detectors
, European Physical Journal C, Vol: 85, ISSN: 1434-6044Volume 1 of the FCC Feasibility Report presents an overview of the physics case, experimental programme, and detector concepts for the Future Circular Collider (FCC). This volume outlines how FCC would address some of the most profound open questions in particle physics, from precision studies of the Higgs and EW bosons and of the top quark, to the exploration of physics beyond the Standard Model. The report reviews the experimental opportunities offered by the staged implementation of FCC, beginning with an electron-positron collider (FCC-ee), operating at several centre-of-mass energies, followed by a hadron collider (FCC-hh). Benchmark examples are given of the expected physics performance, in terms of precision and sensitivity to new phenomena, of each collider stage. Detector requirements and conceptual designs for FCC-ee experiments are discussed, as are the specific demands that the physics programme imposes on the accelerator in the domains of the calibration of the collision energy, and the interface region between the accelerator and the detector. The report also highlights advances in detector, software and computing technologies, as well as the theoretical tools/reconstruction techniques that will enable the precision measurements and discovery potential of the FCC experimental programme. The content and structure of this report are guided by the scope and priorities defined in the mandate of the FCC Feasibility Study. It is therefore not intended to serve as an exhaustive review of the full physics potential of FCC. Several topics, already covered in earlier reports such as the FCC CDR, are not reiterated here or are addressed only briefly, in alignment with the study’s focus. This volume reflects the outcome of a global collaborative effort involving hundreds of scientists and institutions, aided by a dedicated community-building coordination, and provides a targeted assessment of the scientific opportunities and experimental foundations of the F
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Journal articleZwalinski L, Zou W, Zormpa O, et al., 2025,
Total Cost of Ownership and Evaluation of Google Cloud Resources for the ATLAS Experiment at the LHC
, Computing and Software for Big Science, Vol: 9The ATLAS Google Project was established as part of an ongoing evaluation of the use of commercial clouds by the ATLAS Collaboration, in anticipation of the potential future adoption of such resources by WLCG grid sites to fulfil or complement their computing pledges. Seamless integration of Google cloud resources into the worldwide ATLAS distributed computing infrastructure was achieved at large scale and for an extended period of time, and hence cloud resources are shown to be an effective mechanism to provide additional, flexible computing capacity to ATLAS. For the first time a total cost of ownership analysis has been performed, to identify the dominant cost drivers and explore effective mechanisms for cost control. Network usage significantly impacts the costs of certain ATLAS workflows, underscoring the importance of implementing such mechanisms. Resource bursting has been successfully demonstrated, whilst exposing the true cost of this type of activity. A follow-up to the project is underway to investigate methods for improving the integration of cloud resources in data-intensive distributed computing environments and reducing costs related to network connectivity, which represents the primary expense when extensively utilising cloud resources.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for t-channel scalar and vector leptoquark exchange in the high-mass dimuon and dielectron spectra in proton-proton collisions at TeV
, Journal of High Energy Physics, Vol: 2025A search for t-channel exchange of leptoquarks (LQs) is performed in dimuon and dielectron spectra using proton-proton collision data collected at TeV with the CMS detector at the CERN LHC. The data correspond to an integrated luminosity of 138 fb<sup>−1</sup>. Eight scenarios are considered, in which up or down quarks couple to muons or electrons via a scalar or vector LQ exchange, for dilepton invariant masses above 500 GeV. The LQ masses are probed up to 5 TeV, beyond a regime probed by previous pair-production and single-production searches. The differential distributions of dilepton events are fit to templates that model the nonresonant LQ exchange and various standard model background processes. Limits are set on LQ-fermion coupling strengths for scalar and vector LQ masses in the 1–5 TeV range at 95% confidence level, establishing stringent limits on first- and second-generation LQs.
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Journal articleZwalinski L, Zou W, Zormpa O, et al., 2025,
Estimation of backgrounds from jets misidentified as τ-leptons using the Universal Fake Factor method with the ATLAS detector
, European Physical Journal C, Vol: 85, ISSN: 1434-6044Processes with τ-leptons in the final state are important for Standard Model measurements and searches for physics beyond the Standard Model. The ATLAS experiment at the Large Hadron Collider observes τ-leptons produced in proton–proton collisions only through their decay products. Data analyses involving hadronically decaying τ-leptons face challenges due to backgrounds from jets misidentified as τ-leptons that are not modelled reliably by Monte Carlo simulations. Data-driven methods such as the fake-factor method allow such misidentified backgrounds to be predicted by measuring transfer factors, known as fake factors, in data from dedicated regions. This paper describes a refined technique for determining the fake factors, the Universal Fake Factor method. It evaluates the fake factors for a signal region by using fake factors from samples enriched in different sources of jets misidentified as τ-leptons (light-quark, gluon, b-quark, and pile-up jets). Each fake factor is calculated as a linear combination of fake factors measured in these different enriched samples. For the full Run 2 data set, the systematic uncertainty of the calculated fake factors, evaluated using W(μν) enriched event sample, ranges from 15 to 35% depending on the τ-lepton’s transverse momentum and charged-particle decay multiplicity.
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Search for charged-lepton flavour violation in top quark interactions with an up-type quark, a muon, and a τ lepton in proton-proton collisions at TeV
, Journal of High Energy Physics, Vol: 2025A search for charged-lepton flavour violation (CLFV) in top quark (t) production and decay is presented. The search uses proton-proton collision data corresponding to 138 fb<sup>−1</sup> collected with the CMS experiment at TeV. The signal consists of the production of a single top quark via a CLFV interaction or top quark pair production followed by a CLFV decay. The analysis selects events containing a hadronically decaying τ lepton and a muon of opposite electric charge, as well as at least three jets, one of which is identified as originating from the fragmentation of a bottom quark. Machine learning classification techniques are used to distinguish signal from standard model background events. The results of this search are consistent with the standard model expectations. The upper limits at 95% confidence level on the branching fraction for CLFV top quark decays to a muon, a τ lepton, and an up or a charm quark are set at < (0.04, 0.08, and 0.12) × 10<sup>−6</sup>, and < (0.81, 1.71, and 2.05) × 10<sup>−6</sup> for scalar, vector, and tensor-like operators, respectively.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2025,
Search for a new scalar resonance decaying to a Higgs boson and another new scalar particle in the final state with two bottom quarks and two photons in proton-proton collisions at TeV
, Journal of High Energy Physics, Vol: 2025A search is presented for a new scalar resonance, X, decaying to a standard model Higgs boson and another new scalar particle, Y, in the final state where the Higgs boson decays to a pair, while the Y particle decays to a pair of photons. The search is performed in the mass range 240–1000 GeV for the resonance X, and in the mass range 70–800 GeV for the particle Y, using proton-proton collision data collected by the CMS experiment at TeV, corresponding to an integrated luminosity of 132 fb<sup>-1</sup>. In general, the data are found to be compatible with the standard model expectation. Observed (expected) upper limits at 95% confidence level on the product of the production cross section and the relevant branching fraction are extracted for the X ? YH process, and are found to be within the range of 0.05–2.69 (0.08–1.94) fb, depending on m<inf>X</inf> and m<inf>Y</inf>. The most significant deviation from the background-only hypothesis is observed for X and Y masses of 300 and 77 GeV, respectively, with a local (global) significance of 3.33 (0.65) standard deviations.
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Journal articleHall G, 2025,
The evolution of particle physics electronics
, JOURNAL OF INSTRUMENTATION, Vol: 20 -
Journal articleCampagnari C, Cho S, Choi S, et al., 2025,
The Design and Mechanical Integration of Scintillation Modules for the SUB-Millicharge ExperimenT (SUBMET)
, PROGRESS OF THEORETICAL AND EXPERIMENTAL PHYSICS, Vol: 2025, ISSN: 2050-3911 -
Journal articleYamauchi K, Abe K, Abe S, et al., 2025,
Search for neutron decay into an antineutrino and a neutral kaon in 0.401 megaton-years exposure of Super-Kamiokande
, Physical Review D, Vol: 112, Pages: 1-13, ISSN: 2470-0010We searched for bound neutron decay via n → ν̄ + K<sup>0</sup> predicted by the grand unified theories in 0.401 Mton · years exposure of all pure water phases in the Super-Kamiokande detector. About 4.4 times more data than in the previous search have been analyzed by a new method including a spectrum fit to kaon invariant mass distributions. No significant data excess has been observed in the signal regions. As a result of this analysis, we set a lower limit of 7.8 × 10<sup>32</sup> years on the neutron lifetime at a 90% confidence level.
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Journal articleAad G, Aakvaag E, Abbott B, et al., 2025,
Erratum to: Search for neutral long-lived particles that decay into displaced jets in the ATLAS calorimeter in association with leptons or jets using pp collisions at (Formula presented.) = 13 TeV (Journal of High Energy Physics, (2024), 2024, 11, (36), 10.1007/JHEP11(2024)036)
, Journal of High Energy Physics, Vol: 2025Corrections to two figures are noted. In the presentation of exclusion limits for the axion-like particle models, the branching ratio for the decay of the associated W and Z bosons into electron or muon final states was not factored out. For the associated W production mode, this represents a numerical factor of 0.214, while for the Z production model it is a factor of 0.0673. The limits in the plot hence become weaker according to these numerical factors. In addition, the Y-axis labels have been updated to explicitly include the branching ratio of the axion-like particle to gluons. The modified figures are figure 9(a) and figure 10(a).
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Journal articleHayrapetyan A, Tumasyan A, Adam W, et al., 2025,
Performance of heavy-flavour jet identification in Lorentz-boosted topologies in proton-proton collisions at √( <i>s</i> ) = 13 TeV
, Journal of Instrumentation, Vol: 20, Pages: P11006-P11006<jats:title>Abstract</jats:title> <jats:p> Measurements in the highly Lorentz-boosted regime provoke increased interest in probing the Higgs boson properties and in searching for particles beyond the standard model at the LHC. In the CMS Collaboration, various boosted-object tagging algorithms, designed to identify hadronic jets originating from a massive particle decaying to bb̅ or cc̅, have been developed and deployed across a range of physics analyses. This paper highlights their performance on simulated events, and summarizes novel calibration techniques using proton-proton collision data collected at √( <jats:italic>s</jats:italic> ) = 13 TeV during the 2016–2018 LHC data-taking period. Three dedicated methods are used for the calibration in multijet events, leveraging either machine learning techniques, the presence of muons within energetic boosted jets, or the reconstruction of hadronically decaying high-energy Z bosons. The calibration results, obtained through a combination of these approaches, are presented and discussed. </jats:p>
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2025,
A method for correcting the substructure of multiprong jets using the Lund jet plane
, Journal of High Energy Physics, Vol: 2025Many analyses at the CERN LHC exploit the substructure of jets to identify heavy resonances produced with high momenta that decay into multiple quarks and/or gluons. This paper presents a new technique for correcting the substructure of simulated large-radius jets from multiprong decays. The technique is based on reclustering the jet constituents into several subjets such that each subjet represents a single prong, and separately correcting the radiation pattern in the Lund jet plane of each subjet using a correction derived from data. The data presented here correspond to an integrated luminosity of 138 fb<sup>−1</sup> collected by the CMS experiment between 2016–2018 at a center-of-mass energy of 13 TeV. The correction procedure improves the agreement between data and simulation for several different substructure observables of multiprong jets. This technique establishes, for the first time, a robust calibration for the substructure of jets with four or more prongs, enabling future measurements and searches for new phenomena containing these signatures.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
Search for a cH signal in the associated production of at least one charm quark with a Higgs boson in the diphoton decay channel in pp collisions at TeV
, Journal of High Energy Physics, Vol: 2025This paper presents the first search for a cH signal sensitive to the coupling of the charm quark (c) to the Higgs boson (H) in the associated production of at least one charm quark with a Higgs boson decaying to two photons. The results are based on a data set of proton-proton collisions at a center-of-mass energy of 13 TeV collected with the CMS experiment at the LHC, corresponding to an integrated luminosity of 138 fb<sup>−1</sup>. Assuming the standard model (SM) rates for all other Higgs boson production processes, the observed (expected) upper limit at 95% confidence level on the cH signal strength is 243 (355) times the SM prediction. Under the same assumption, the observed (expected) allowed interval on the Higgs boson to charm quark coupling modifier, κ<inf>c</inf>, is |κ<inf>c</inf>| < 38.1 (|κ<inf>c</inf>| < 72.5) at 95% confidence level.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
Inclusive B-meson flavour-tagging algorithm at LHCb
, Journal of High Energy Physics, Vol: 2025A new algorithm is developed to identify the flavour of neutral B mesons at production in pp collisions by utilising all tracks from the hadronisation process. The algorithm is calibrated separately for B<sup>0</sup> and Bs0 mesons using B<sup>0</sup> → J/ψK<sup>+</sup>π<sup>−</sup> and Bs0→Ds−π+ decays from pp collision data collected by the LHCb experiment at a centre-of-mass energy of 13 TeV. This new algorithm improves the tagging power by 35% for B<sup>0</sup> mesons and 20% for Bs0 mesons when compared to the combined performance of the existing LHCb flavour-tagging algorithms.
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Journal articleZwalinski L, Zou W, Zormpa O, et al., 2025,
A continuous calibration of the ATLAS flavour-tagging classifiers via optimal transportation maps
, European Physical Journal C, Vol: 85, ISSN: 1434-6044A calibration of the ATLAS flavour-tagging algorithms using a new calibration procedure based on optimal transportation maps is presented. Simultaneous, continuous corrections to the b-jet, c-jet, and light-flavour jet classification probabilities from jet-tagging algorithms in simulation are derived for b-jets using tt¯→eμννbb data. After application of the derived calibration maps, closure between simulation and observation is achieved for jet flavour observables used in ATLAS analyses of Large Hadron Collider (LHC) Run 2 proton-proton collision data. This continuous calibration opens up new possibilities for the future use of jet flavour information in LHC analyses and also serves as a guide for deriving high-dimensional corrections to simulation via transportation maps, an important development for a broad range of inference tasks.
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