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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Physics Letters B, Vol: 876, Pages: 140359-140359, ISSN: 0370-2693
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Journal articleTomalak O, Meyer AS, Wret C, et al., 2026, , Physical Review D, Vol: 113, ISSN: 2470-0010
<jats:p> The nucleon axial-vector form factor, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:msub> <a:mi>G</a:mi> <a:mi>A</a:mi> </a:msub> </a:math> , is critical to determine the electroweak interactions of leptons with nucleons. Important examples of processes influenced by <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" display="inline"> <c:msub> <c:mi>G</c:mi> <c:mi>A</c:mi> </c:msub> </c:math> are elastic (anti)neutrino-nucleon scattering and muon capture by the proton. Sparse experimental data results in a large uncertainty on the momentum dependence of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:msub> <e:mi>G</e:mi> <e:mi>A</e:mi> </e:msub> </e:math> and has motivated the consideration of new experimental probes and first-principles lattice quantum chromodynamics (QCD) evaluations. The comparison of new and precise theoretical predictions for <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:msub> <g:mi>G</g:mi> <g:mi>A</g:mi> </g:msub> </g:math> with future experimental data necessitates the application of radiat
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Journal articleMiki S, Abe K, Abe S, et al., 2026, , Phys Rev Lett, Vol: 136
In recent neutrino detectors, neutrons produced in neutrino reactions play an important role. Muon capture on oxygen nuclei is one of the processes that produce neutrons in water Cherenkov detectors. We measured neutron multiplicity in the process using cosmic ray muons that stop in the gadolinium-loaded Super-Kamiokande detector. For this measurement, neutron detection efficiency is obtained with the muon capture events followed by gamma rays to be 50.2_{-2.1}^{+2.0}%. By fitting the observed multiplicity considering the detection efficiency, we measure neutron multiplicity in muon capture as P(0)=24±3%, P(1)=70_{-2}^{+3}%, P(2)=6.1±0.5%, P(3)=0.38±0.09%. This is the first measurement of the multiplicity of neutrons associated with muon capture on oxygen without neutron energy threshold.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2026, , The European Physical Journal C, Vol: 86
<jats:title>Abstract</jats:title> <jats:p> Constraints on Wilson coefficients (WCs) corresponding to dimension-6 operators of the standard model effective field theory (SMEFT) are determined from a simultaneous fit to seven sets of CMS measurements probing Higgs boson, electroweak vector boson, top quark, and multijet production. Measurements of electroweak precision observables are also included and provide complementary constraints to those from the CMS experiment. The CMS measurements, using LHC proton-proton collision data at <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\sqrt{s}=13\,\text {Te}\text {V} $$</jats:tex-math> <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:mspace/> <mml:mrow> <mml:mtext>Te</mml:mtext> <mml:mspace/> </mml:mrow> </mml:mrow> </mml:math> </jats:alternatives> </jats:inline-formula> , corresponding to integrated luminosities of 36.3 or 138 <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$\,\text {fb}^{-1}$$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML">
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Journal of Instrumentation, Vol: 21, Pages: P04002-P04002
<jats:title>Abstract</jats:title> <jats:p> The trigger system of the CMS detector is pivotal in the acquisition of data for physics measurements and searches. Studies of final states characterized by hadronic decays of tau leptons require the reconstruction and the identification of genuine tau leptons against quark- and gluon-initiated jets at the trigger level. This is a difficult task, particularly as improvements to the LHC have resulted in an increased number of interactions per bunch crossing in recent years. To address this challenge, a series of machine-learning algorithms with high identification efficiency and low computational cost have been incorporated into the high-level trigger for hadronically decaying tau leptons. In this paper, these developments and the trigger performance are summarized using data collected by the CMS experiment in proton-proton collisions at √( <jats:italic>s</jats:italic> ) = 13.6 TeV in 2022–2023, corresponding to an integrated luminosity of 62 fb <jats:sup>-1</jats:sup> . </jats:p>
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Journal articleSummers S, Tapper A, Årrestad TK, et al., 2026, , Machine Learning: Science and Technology, Vol: 7, Pages: 021501-021501
<jats:title>Abstract</jats:title> <jats:p>The need for microsecond speed machine learning (ML) inference for particle physics experiments has emerged in recent years, in particular for the forthcoming upgrades to the experiments at the Large Hadron Collider at CERN. A community has grown around the need to develop the custom hardware platforms and tools required. The material presented in this report is drawn from the latest workshop held by the fast ML for science community and comprises of a collection of perspectives on the status of fast ML in different scientific domains, and the supporting technology.</jats:p>
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Journal articleAbdullahi AM, Abratenko P, Andrade Aldana D, et al., 2026, , Phys Rev Lett, Vol: 136
We present MicroBooNE's first search for dark sector e^{+}e^{-} explanations of the long-standing MiniBooNE anomaly. The MiniBooNE anomaly has garnered significant attention over the past 20 years including previous MicroBooNE investigations into both anomalous electron and photon excesses, but its origin still remains unclear. In this Letter, we provide the first direct test of dark sector models in which dark neutrinos, produced through neutrino-induced scattering, decay into missing energy and visible e^{+}e^{-} pairs comprising the MiniBooNE anomaly. Many such models have recently gained traction as a viable solution to the anomaly while evading past bounds. Using an exposure of 6.87×10^{20} protons-on-target in the Booster Neutrino Beam, we implement a selection targeting forward-going, coherently produced e^{+}e^{-} events. After unblinding, we observe 95 events, which we compare with the constrained background-only prediction of 69.7±17.3. This analysis sets the world's first direct limits on these dark sector models and, at the 95% confidence level, excludes the entirety of the single dark neutrino and majority of the dual dark neutrino, parameter space that is viable as a solution to the MiniBooNE anomaly.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2026, , Phys Rev Lett, Vol: 136
This Letter reports the first measurement of photonuclear D^{0} meson production in ultraperipheral heavy ion collisions. The study is performed using lead-lead collision data, with an integrated luminosity of 1.34 nb^{-1}, collected by the CMS experiment at a nucleon-nucleon center-of-mass energy of 5.36 TeV. Photonuclear events, where one of the colliding nuclei breaks up and the other remains intact, are selected based on breakup neutron emissions and by requiring no particle activity in a large rapidity interval in the direction of the photon-emitting nucleus. The D^{0} mesons are reconstructed via the D^{0}→K^{-}π^{+} decay channel, with the cross section measured as a function of D^{0} meson transverse momentum and rapidity. The results are compared with next-to-leading-order perturbative QCD calculations that employ recent parametrizations of the lead nuclear parton distribution functions, as well as with predictions based on the color glass condensate framework. This measurement is the first photonuclear collision study characterizing parton distribution functions of lead nuclei for parton fractional momenta x (relative to the nucleon) ranging approximately from a few 10^{-4} to 10^{-2} for different hard energy scale Q^{2} selections.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Journal of High Energy Physics, Vol: 2026
<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> A search for signatures of a dark analog to quantum chromodynamics is performed. The analysis targets long-lived dark mesons that decay into standard-model particles, with a high branching fraction of the dark mesons decaying into muons. The dark mesons are formed by the hadronisation of dark partons, which are produced by a decay of the Higgs boson. The search is performed using a data set corresponding to an integrated luminosity of 41.6 fb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> , which was collected in proton-proton collisions at <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ \sqrt{s}=13 $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msqrt> <mml:mi>s</mml:mi> </mml:msqrt> <mml:mo>=</mml:mo> <mml:mn>13</mml:mn> </mml:math> </jats:alternatives> </jats:inline-formula> TeV by the CMS experiment at the CERN LHC in 2018 using non-prompt muon triggers. The search is based on resonant muon pair signatures. Machine-learning techniques are employed in the analysis, utilising boosted decision trees to discriminate between signal and background. No significant excess is observed above the standard model expectation. Upper limits on the branching fraction of the Higgs boson decaying to dark partons are determine
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Journal articleAbbaslu S, Abud AA, Acciarri R, et al., 2026, , Instruments, Vol: 10, Pages: 18-18
<jats:p>The 2x2 Demonstrator, a prototype for the Deep Underground Neutrino Experiment (DUNE) liquid argon (LAr) Near Detector, was exposed to the Neutrinos from the Main Injector (NuMI) neutrino beam at Fermi National Accelerator Laboratory (Fermilab). This detector is a prototype of a new modular design for a liquid argon time-projection chamber (LArTPC), comprising a two-by-two array of four modules, each further segmented into two optically isolated LArTPCs. The 2x2 Demonstrator features a number of pioneering technologies, including a low-profile resistive field shell to establish drift fields, native 3D ionization pixelated imaging, and a high-coverage dielectric light readout system. The 2.4-tonne active mass detector is flanked upstream and downstream by supplemental solid-scintillator tracking planes, repurposed from the MINERvA experiment, which track ionizing particles exiting the argon volume. The antineutrino beam data collected by the detector over a 4.5 day period in 2024 include over 30,000 neutrino interactions in the LAr active volume—the first neutrino interactions reported by a DUNE detector prototype. During its physics-quality run, the 2x2 Demonstrator operated at a nominal drift field of 500 V/cm and maintained good LAr purity, with a stable electron lifetime of approximately 1.25 ms. This paper describes the detector and supporting systems, summarizes the installation and commissioning, and presents the initial validation of collected NuMI beam and off-beam self-triggers. In addition, it highlights observed interactions in the detector volume, including candidate muon antineutrino events.</jats:p>
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Physical Review D, Vol: 113, ISSN: 2470-0010
<jats:p> Measurements of the spin correlation coefficients in the beam basis are presented for top quark-antiquark ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mi>t</a:mi> <a:mover accent="true"> <a:mi>t</a:mi> <a:mo stretchy="false">¯</a:mo> </a:mover> </a:math> ) systems produced in proton-proton collisions at <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" display="inline"> <e:msqrt> <e:mi>s</e:mi> </e:msqrt> <e:mo>=</e:mo> <e:mn>13</e:mn> <e:mtext> </e:mtext> <e:mtext> </e:mtext> <e:mi>TeV</e:mi> </e:math> collected by the CMS experiment in 2016–2018, and corresponding to an integrated luminosity of <g:math xmlns:g="http://www.w3.org/1998/Math/MathML" display="inline"> <g:mn>138</g:mn> <g:mtext> </g:mtext> <g:mtext> </g:mtext> <g:msup> <g:mi>fb</g:mi> <g:mrow> <g:mo>−</g:mo> <g:mn>1</g:mn> </g:mrow> </g:msup> </g:math> . The <i:math xmlns
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Journal of High Energy Physics, Vol: 2026
<jats:title> A <jats:sc>bstract</jats:sc> </jats:title> <jats:p> Measurements of properties of top quark-antiquark pair production in association with a W boson in proton-proton collisions at a center-of-mass energy of 13 TeV are presented, using a data sample corresponding to an integrated luminosity of 138 fb <jats:sup> <jats:italic>−</jats:italic> 1 </jats:sup> , recorded by the CMS experiment at the CERN LHC. Events are selected based on the presence of either two leptons with the same electric charge or three leptons, and multiple jets and b-tagged jets. We present measurements of differential production cross sections as a function of kinematic variables sensitive to different aspects of the process modeling, using a multivariate discriminator in the two-lepton selection region and a simple selection-based method in the three-lepton region. The normalized cross section measurements are generally consistent with the standard model expectations, while we observe larger values compared to the expectations in the absolute cross section measurements, consistent with previous inclusive cross section measurements. In addition, we measure the leptonic charge asymmetry of this process, obtaining an observed value of <jats:inline-formula> <jats:alternatives> <jats:tex-math>$$ {A}_c^{\ell }=-{0.19}_{-0.18}^{+0.16} $$</jats:tex-math> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>A</mml:mi> <mml:mi>c</mml:mi> <mml:mi>ℓ</mml:mi&g
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Journal articleAbbaslu S, Abd Alrahman F, Abed Abud A, et al., 2026, , Physical Review D, Vol: 113, ISSN: 2470-0010
<jats:p> The Deep Underground Neutrino Experiment (DUNE) is a next-generation neutrino experiment with a rich physics program that includes searches for the hypothetical phenomenon of proton decay. Utilizing liquid-argon time-projection chamber technology, DUNE is expected to achieve world-leading sensitivity in the proton decay channels that involve charged kaons in their final states. The first DUNE demonstrator, ProtoDUNE Single-Phase, was a 0.77 kt detector that operated from 2018 to 2020 at the CERN Neutrino Platform, exposed to a mixed hadron and electron test-beam with momenta ranging from 0.3 to <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"> <a:mrow> <a:mn>7</a:mn> <a:mtext> </a:mtext> <a:mtext> </a:mtext> <a:mi>GeV</a:mi> <a:mo>/</a:mo> <a:mi mathvariant="normal">c</a:mi> </a:mrow> </a:math> . We present a selection of low-energy kaons among the secondary particles produced in hadronic reactions, using data from the 6 and <d:math xmlns:d="http://www.w3.org/1998/Math/MathML" display="inline"> <d:mrow> <d:mn>7</d:mn> <d:mtext> </d:mtext> <d:mtext> </d:mtext> <d:mi>GeV</d:mi> <d:mo>/</d:mo> <d:mi mathvariant="normal">c</d:mi> </d:mrow> </d:math> beam runs. The selecti
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026, , Journal of High Energy Physics, Vol: 2026
The pp → W<sup>±</sup>(→ μ<sup>±</sup>ν<inf>μ</inf>)X cross-sections are measured at a proton-proton centre-of-mass energy s=5.02 TeV using a dataset corresponding to an integrated luminosity of 100 pb<sup>−1</sup> recorded by the LHCb experiment. Considering muons in the pseudorapidity range 2.2 < η < 4.4, the cross-sections are measured differentially in twelve intervals of muon transverse momentum between 28 < p<inf>T</inf>< 52 GeV. Integrated over p<inf>T</inf>, the measured cross-sections are (Formula presented.) where the first uncertainties are statistical, the second are systematic, and the third are associated with the luminosity calibration. These integrated results are consistent with theoretical predictions. This analysis introduces a new method to determine the W-boson mass using the measured differential cross-sections corrected for detector effects. The measurement is performed on this statistically limited dataset as a proof of principle and yields (Formula presented.) where the first uncertainty is experimental and the second is theoretical.
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Journal articleHunter ED, Bumbar M, Amsler C, et al., 2026, , Physics of Plasmas, Vol: 33, ISSN: 1070-664X
We present advances in plasma control and diagnosis, leading to the production of exceptionally large quantities of neutral antimatter. We measure the time-dependent temperature and density distribution of antiprotons and positrons while slowly combining them to make antihydrogen atoms in a nested Penning–Malmberg trap. The total antihydrogen yield and the number of atoms escaping the trap as a beam are greatest when the positron temperature is lowest and when antiprotons enter the positron plasma at the smallest radius. We control these parameters by changing the rate at which we lower the electrostatic barrier between the antiproton and positron plasmas and by heating the positrons. With the optimal settings, we produce 2.3 × 10<sup>6</sup> antihydrogen atoms per 15-min run, surpassing the previous state of the art (3.1 × 10<sup>4</sup> atoms in 4 min) and the most recent advances in other experiments by factors of 20 and 5, respectively.
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Journal articleScandale W, Giroldi S, Hall G, et al., 2026, , Journal of Instrumentation, Vol: 21
Established in 2010, the UA9 Collaboration primarily studies the interactions of high-energy particles with bent silicon crystals using a specialized apparatus on the H8 beam line at CERN-SPS North Area. Crystals of various shapes are studied using high-energy beams of hadrons or leptons for purposes like crystal collimation, beam extraction, reducing hardware irradiation, and importantly, beam merging. The usual crystals are either tiny strips or rectangular slabs, bent along a main axis to create an orthogonal anticlastic response. We introduce an optical technique utilizing autocollimators to accurately determine the two crystal curvatures with an unmatched level of precision. Applying it to crystals addresses the challenge of rapid crystal curvature measurement in the lab, eliminating the trial and error method based on particle irradiation to significantly decrease the required beam time. Comparisons of the optical measurements with beam-based assessments demonstrate a significant similarity between the methods.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026, , Journal of High Energy Physics, Vol: 2026
A search for long-lived heavy neutral leptons produced in B-meson decays and decaying to a μ<sup>±</sup>π<sup>∓</sup> final state is performed with data collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5 fb<sup>−1</sup>. The results are interpreted in both lepton-number-conserving and lepton-number-violating scenarios. No significant excess is observed. Constraints are placed on the squared mixing element |U<inf>μN</inf>|<sup>2</sup> to the active muon neutrino, under the assumption that couplings to other lepton flavours are negligible, in the mass range of 1.6–5.5 GeV.
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Journal articleCampagnari C, Cho S, Choi S, et al., 2026, , Progress of Theoretical and Experimental Physics, Vol: 2026
The SUB-Millicharge ExperimenT (SUBMET) investigates an unexplored parameter spaceof millicharged particles with mass m<inf>χ</inf> < 1.6 GeV/c2 and charge Q<inf>χ</inf> < 10<sup>−3</sup> e. The detec-tor consists of an Eljen-200 plastic scintillator coupled to a Hamamatsu Photonics R7725photomultiplier tube (PMT). PMT afterpulses, delayed pulses produced after an energeticpulse, have been observed in the SUBMET readout system, especially following primarypulses with a large area. We present a prediction method for afterpulse rates based onmeasurable parameters, which reproduces the observed rate with approximately 20% pre-cision. This approach enables a better understanding of afterpulse contributions and, con-sequently, improves the reliability of background predictions
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Journal of High Energy Physics, Vol: 2026
A model-independent measurement of the differential production cross section of the Higgs boson decaying into a pair of W bosons, with a final state including two jets produced in association, is presented. In the analysis, events are selected in which the decay products of the two W bosons consist of an electron, a muon, and missing transverse momentum. The model independence of the measurement is maximized by employing a discriminating variable, developed through machine learning, that is agnostic to the signal hypothesis. The analysis is based on proton-proton collision data at s=13 TeV collected with the CMS detector from 2016–2018, corresponding to an integrated luminosity of 138 fb<sup>−1</sup>. The production cross section is measured as a function of the difference in azimuthal angle between the two jets. The differential cross section measurements are used to constrain Higgs boson couplings within the standard model effective field theory framework.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Journal of High Energy Physics, Vol: 2026
A measurement is presented of the electroweak vector boson scattering production of ZV (V = W, Z) boson pairs associated with two jets in proton-proton collisions at a center-of-mass energy of 13 TeV. The data, corresponding to an integrated luminosity of 138 fb<sup>−1</sup>, were collected at the CERN LHC with the CMS detector during the 2016–2018 data-taking period. The analysis targets final states with a pair of isolated electrons or muons from Z boson decays and three or four jets, depending on the momentum of the vector boson that decays into quarks. Signal strength is measured for events characterized by a large invariant mass of two forward jets with a wide pseudorapidity gap between them. The electroweak production of ZV in association with two jets is measured with an observed (expected) significance of 1.3 (1.8) standard deviations. A combination of the analyses of ZV channel and the previously published WV channel in the lepton plus jets final state places constraints on effective field theory parameters that describe anomalous electroweak production of WW, WZ, and ZZ boson pairs in association with two jets. Several world best limits are set on anomalous quartic gauge couplings in terms of dimension-8 standard model effective field theory operators.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Journal of High Energy Physics, Vol: 2026
An analysis of the flavour structure of dimension-6 effective field theory (EFT) operators in multilepton final states is presented, focusing on the interactions of quarks with Z bosons. For the first time, the flavour structure of these operators is disentangled by simultaneously probing the interactions with different quark generations. The analysis targets the associated production of a top quark pair and a Z boson, as well as diboson processes in final states with at least three leptons, which can be electrons or muons. The data were recorded by the CMS experiment in the years 2016–2018 in proton-proton collisions at a centre-of-mass energy of 13 TeV and correspond to an integrated luminosity of 138 fb<sup>−1</sup>. Consistency with the standard model of particle physics is observed and limits are set on the selected Wilson coefficients, split into couplings to light- and heavy-quark generations.
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Journal articleDauncey PD, Shukla R, Vojinovic M, 2026, , Journal of Instrumentation, Vol: 21, Pages: C03019-C03019
<jats:title>Abstract</jats:title> <jats:p>Timing and control firmware was developed to operate a vertical slice of the CMS High-Granularity Calorimeter on- and off-detector systems at beam tests, in the absence of a fully fledged system. It provides various trigger sources (software, regular, random, external), throttling mechanisms and a programmable sequencer for fast commands. A data capture block for local readout of the outgoing event data through direct software access complements this development. Such integration facilitates the development of stand-alone test systems without specializedtiming/trigger distribution or DAQ hardware. The modular design of the firmware and software enableseasier adaptation for other detector subsystems.</jats:p>
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2026, , Physics Letters B, Vol: 874, Pages: 140120-140120, ISSN: 0370-2693
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026, , Phys Rev Lett, Vol: 136
The first observation of single top quark production in association with a W and a Z boson in proton-proton collisions is reported. The analysis uses data at center-of-mass energies of 13 and 13.6 TeV recorded with the CMS detector at the CERN LHC, corresponding to a total integrated luminosity of 200 fb^{-1}. Events with three or four charged leptons, which can be electrons or muons, are selected. Advanced machine-learning algorithms and improved reconstruction methods, compared to an earlier analysis, result in an unprecedented sensitivity to tWZ production. The measured cross sections for tWZ production are 248±52 fb and 242±77 fb for sqrt[s]=13 and 13.6 TeV, respectively. The signal is established with a statistical significance of 5.8 standard deviations, with 3.5 expected, compared to the background-only hypothesis.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026, , Science Bulletin, Vol: 71, Pages: 547-557, ISSN: 2095-9273
A study of the difference in the CP asymmetries between Λ<inf>b</inf><sup>0</sup>→J/ψpπ<sup>-</sup> and Λ<inf>b</inf><sup>0</sup>→J/ψpK<sup>-</sup> decays, ΔA<inf>CP</inf>, is performed using proton-proton collision data collected by the LHCb experiment in the years 2015–2018, corresponding to an integrated luminosity of 6fb<sup>-1</sup>. This quantity is measured to be ΔA<inf>CP</inf>=(4.03±1.18±0.23)%, where the first uncertainty is statistical and the second is systematic. When combined with the previous LHCb result, a value of ΔA<inf>CP</inf>=(4.31±1.06±0.28)% is obtained, corresponding to a significance of 3.9σ against the CP symmetry hypothesis. Studies of triple-product asymmetries, which provide an additional probe of CP violation, show no significant deviation from CP symmetry.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026, , Phys Rev Lett, Vol: 136
A search is presented for the two-body charmed baryonic decays, B[over ¯]_{(s)}^{0}→Λ_{c}^{+}Λ[over ¯]_{c}^{-}, using a data sample collected by the LHCb experiment during 2011-2012 and 2015-2018, corresponding to an integrated luminosity of 9 fb^{-1}. The first observation of the B[over ¯]_{s}^{0}→Λ_{c}^{+}Λ[over ¯]_{c}^{-} decay is reported with 6.2σ significance along with 4.3σ evidence for the B[over ¯]^{0}→Λ_{c}^{+}Λ[over ¯]_{c}^{-} decay. The branching fractions are measured to be B(B[over ¯]^{0}→Λ_{c}^{+}Λ[over ¯]_{c}^{-})=(1.01_{-0.28}^{+0.27}±0.08±0.15)×10^{-5} and B(B[over ¯]_{s}^{0}→Λ_{c}^{+}Λ[over ¯]_{c}^{-})=(5.0±1.3±0.5±0.8)×10^{-5}, where the first uncertainty is statistical, the second systematic, and the third due to external inputs. These results provide novel experimental inputs for the theoretical framework describing two-body baryonic decays of B mesons via W-emission and W-exchange mechanisms.
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Journal articleAbratenko P, Aldana DA, Arellano L, et al., 2026, , Physical Review D, Vol: 113, ISSN: 2470-0010
We present flux-integrated charged-current νμ cross-section measurements on argon for final states containing exactly one n± and no other hadrons except nucleons. The analysis uses data from the MicroBooNE experiment in the Booster Neutrino Beam, corresponding to 1.11 × 1021 protons on target. Total and single-differential cross-section measurements are provided within a phase space restricted to muon momenta above 150 MeV, pion momenta above 100 MeV, and muon-pion opening angles smaller than 2.65 rad. Differential cross sections are reported with respect to the scattering angles of the muon and pion relative to the beam direction, their momenta, and their combined opening angle. The differential cross section with respect to muon momentum is based on a subset of selected events with the muon track fully contained in the detector, whereas the cross section with respect to pion momentum is based on a subset of selected events rich in pions that have not hadronically scattered on the argon before coming to rest. The latter has not been measured on argon before. The total cross section is measured as (3.75 ± 0.07(stat) ± 0.80(syst)) x 10−38 cm2/Ar at a mean energy of approximately 0.8 GeV. Comparisons of the measured cross sections with predictions from multiple neutrino-nucleus interaction generators show good overall agreement, except at very forward muon angles.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026, , Phys Rev Lett, Vol: 136
The first observation of the decay B^{+}→pΛ[over ¯] is presented using proton-proton collision data collected by the LHCb experiment between 2016 and 2018 at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb^{-1}. The signal significance exceeds seven standard deviations. Using the B^{+}→K_{S}^{0}π^{+} decay as a normalization channel, the branching fraction is measured and combined with previous LHCb results based on data collected at 7 and 8 TeV in 2011 and 2012, yielding B(B^{+}→pΛ[over ¯])=(1.24±0.17±0.05±0.03)×10^{-7}, where the first uncertainty is statistical, the second is systematic, and the third comes from the uncertainty on the branching fraction of the normalization channel. The B^{+}→pΛ[over ¯] weak decay parameter is measured to be α_{B}=0.87_{-0.29}^{+0.26}±0.09, indicating the presence of comparable S-wave and P-wave decay amplitudes.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2026, , Journal of High Energy Physics, Vol: 2026
A search for nonresonant new physics phenomena in high-mass dilepton events produced in association with b-tagged jets is performed using proton-proton collision data collected in 2016–2018 by the CMS experiment at the CERN LHC, at a center-of-mass energy of 13 TeV corresponding to an integrated luminosity of 138 fb<sup>−1</sup>. The analysis considers two effective field theory models with dimension-six operators; involving four-fermion contact interactions between two leptons (ℓℓ, electrons or muons) and b or s quarks (bbℓℓ and bsℓℓ). Two lepton flavor combinations (ee and μμ) are required and events are classified as having 0, 1, or ≥2 b-tagged jets in the final state. No significant excess is observed over the standard model backgrounds. Upper limits are set on the production cross section of the new physics signals. These translate into lower limits on the energy scale Λ of 6.9 to 9.0 TeV in the bbℓℓ model, depending on model parameters, and on the ratio of energy scale and effective coupling, Λ/g<inf>*</inf>, of 2.0 to 2.6 TeV in the bsℓℓ model. Lepton flavor universality is also tested by comparing the dielectron (ee) and dimuon (μμ) mass spectra for different b-tagged jet multiplicities. No significant deviation from the standard model expectation of unity is observed.
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ReportAhmed H, Alderton M, Amos RA, et al., 2026, , STFC Technical Reports, Publisher: UKRI
This document, the principal deliverable of the Preliminary Activity, presents the conceptual design for LhARA to serve the ITRF. The conceptual design of the accelerator facility is presented in Chapter 2. Comparison of the laser-hybrid solution with the conventional alternatives has allowed the LhARA approach to be confirmed as the baseline design [15]. The conceptual design for the facility is shown in figure 1.
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