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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2026,
Search for nonresonant new physics signals in high-mass dilepton events produced in association with b-tagged jets in proton-proton collisions at TeV
, Journal of High Energy Physics, Vol: 2026A 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,
ITRF/LhARA conceptual design report
, STFC Technical Reports, Publisher: UKRIThis 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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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
Measurement of CP asymmetry in D0→KS0KS0 decays with Run 3 data
, Journal of High Energy Physics, Vol: 2026A measurement of CP asymmetry in D0→KS0KS0 decays is reported, based on a data sample of proton-proton collisions collected with the LHCb detector in 2024 at a centre-of-mass energy of 13.6 TeV, corresponding to an integrated luminosity of 6.2 fb<sup>−1</sup>. The D0→KS0π+π− decay is used as calibration channel to cancel residual detection and production asymmetries. The time-integrated CP asymmetry for the D0→KS0KS0 mode is measured to be (Formula presented.) where the first uncertainty is statistical, and the second is systematic. This measurement represents the most precise single-experiment determination of this quantity to date.
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Journal articleZsoldos S, Zito M, Zietara K, et al., 2026,
Sensitivity of the Hyper-Kamiokande experiment to neutrino oscillation parameters using accelerator neutrinos
, European Physical Journal C, Vol: 86, ISSN: 1434-6044This paper presents the expected sensitivity to the neutrino oscillation parameters of the Hyper-Kamiokande long-baseline program. The Hyper-Kamiokande experiment, currently under construction in Japan, will measure the oscillations of accelerator-produced neutrinos with thousands of selected events per sample: this corresponds to an increase of statistics of a factor 25–100 with respect to recent results from the currently-running long-baseline neutrino oscillation experiment in Japan, T2K. In the most favorable scenario we will achieve the discovery of Charge-Parity (CP) violation in neutrino oscillation at 5σ C.L. in less than 3 years. With 10 years of data-taking, and assuming a neutrino : antineutrino beam running ratio of 1:3, a CP violation discovery at 5σ C.L. is possible for more than 60% of the actual values of the CP-violating phase, δCP. Moreover, we will measure δCP with a precision ranging from 20∘, in the case of maximal CP violation, to 6∘, in the case of CP conservation. We aim to achieve a 0.5% resolution on the Δm322 parameter, and a resolution between 3% and 0.5% on the sin2θ23 parameter, depending on its true value. These results are obtained by extending the analysis methods of T2K with dedicated tuning to take into account the Hyper-Kamiokande design: the larger far detector, the more powerful beam, the upgraded near detector ND280, and the planned additional Intermediate Water Cherenkov Detector.
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Journal articleAad G, Bertrand R, Laatu L, et al., 2026,
Optimised neural networks for online processing of ATLAS calorimeter data on FPGAs
, European Physical Journal C, Vol: 86, ISSN: 1434-6044A study of neural network architectures for the reconstruction of the energy deposited in the cells of the ATLAS liquid-argon calorimeters under high pile-up conditions expected at the HL-LHC is presented. These networks are designed to run on the FPGA-based readout hardware of the calorimeters under strict size and latency constraints. Several architectures, including Dense, recurrent (RNN), and convolutional (CNN) neural networks, are optimised using a Bayesian procedure that balances energy resolution against network size. The optimised Dense, CNN, and combined Dense+RNN architectures achieve a transverse energy resolution of approximately 80 MeV, outperforming both the optimal filtering (OF) method currently in use and RNNs of similar complexity. A detailed comparison across the full dynamic range shows that Dense, CNN, and Dense+RNN accurately reproduce the energy scale, while OF and RNNs underestimate the energy. Deep evidential regression is implemented within the Dense architecture to address the need for reliable per-event energy uncertainties. This approach provides predictive uncertainty estimates with minimal increase in network size. The predicted uncertainty is found to be consistent, on average, with the difference between the true deposited energy and the predicted energy.
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Journal articleOishi K, Aoki M, Kuribayashi S, et al., 2026,
Development of the Range Counter for the COMET Phase-α Experiment
, NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT, Vol: 1082, ISSN: 0168-9002 -
Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
First Exclusive Reconstruction of the B^{*+}, B^{*0}, and B_{s}^{*0} Mesons and Precise Measurement of Their Masses.
, Phys Rev Lett, Vol: 136Using proton-proton collision data collected by the CMS experiment at sqrt[s]=13 TeV in 2016-2018, corresponding to an integrated luminosity of 140 fb^{-1}, the first full reconstruction of the three vector B meson states, B^{*+}, B^{*0}, and B_{s}^{*0}, is performed. The mass differences between the excited mesons and their corresponding ground states are measured to be m(B^{*+})-m(B^{+})=45.277±0.039±0.027 MeV, m(B^{*0})-m(B^{0})=45.471±0.056±0.028 MeV, and m(B_{s}^{*0})-m(B_{s}^{0})=49.407±0.132±0.041 MeV, where the first uncertainties are statistical and the second are systematic. These results improve on the precision of previous measurements by an order of magnitude.
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Journal articleNakanishi F, Abe K, Abe S, et al., 2026,
First Associated Neutrino Search for a Failed Supernova Candidate with Super-Kamiokande
, Astrophysical Journal Letters, Vol: 997, ISSN: 2041-8205In 2024, a failed supernova (SN) candidate, M31-2014-DS1, was reported in the Andromeda galaxy (M31), located at a distance of approximately 770 kpc. In this Letter, we search for neutrinos from this failed SN using data from Super-Kamiokande (SK). Based on the estimated time of black hole formation inferred from optical and infrared observations, we define a search window for neutrino events in the SK data. Using this window, we develop a dedicated analysis method for failed SNe and apply it to M31-2014-DS1, by conducting a cluster search using the timing and energy information of candidate events. No significant neutrino excess is observed within the search region. Consequently, we place an upper limit on the time-integrated electron antineutrino luminosity from M31-2014-DS1 and discuss its implications for various failed SN models and their neutrino emission characteristics. Despite the 18 MeV threshold adopted to suppress backgrounds, the search remains sufficiently sensitive to constrain the Shen-TM1 equation of state, in a more optimistic emission scenario with progenitor stars of 40 M<inf>⊙</inf> and relatively high mean electron-antineutrino energies of about 23.2 MeV, yielding a 90% confidence level upper limit of 1.76 × 10<sup>53</sup> erg on the time-integrated electron antineutrino luminosity, moderately above the expected value of 1.35 × 10<sup>53</sup> erg.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
First Observation of CP Violation and Measurement of Polarization in B^{+}→ρ(770)^{0}K^{*}(892)^{+} Decays.
, Phys Rev Lett, Vol: 136An amplitude analysis of the B^{+}→(π^{+}π^{-})(K_{S}^{0}π^{+}) decay is performed in the mass regions 0.30<m_{π^{+}π^{-}}<1.10 GeV/c^{2} and 0.75<m_{K_{S}^{0}π^{+}}<1.20 GeV/c^{2}, using pp collision data recorded with the LHCb detector corresponding to an integrated luminosity of 9 fb^{-1}. The polarization fractions and CP asymmetries for B^{+}→ρ(770)^{0}K^{*}(892)^{+} decays are measured. Violation of the CP symmetry in the decay B^{+}→ρ(770)^{0}K^{*}(892)^{+} is observed for the first time, with a significance exceeding 9 standard deviations. The CP asymmetry is measured to be A_{CP}=0.507±0.062(stat)±0.024(syst) and the CP-averaged longitudinal polarization fraction of f_{L}=0.720±0.028(stat)±0.009(syst). The measurements help to shed light on the polarization puzzle of B mesons decaying to two vector mesons.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Search for b-hadron decays to long-lived particles in the CMS endcap muon detectors
, Physical Review D, Vol: 113, ISSN: 2470-0010A search for long-lived particles originating from the decay of b hadrons produced in proton-proton collisions with a center-of-mass energy of 13 TeV at the LHC is presented. The analysis is performed on a dataset recorded in 2018, corresponding to an integrated luminosity of 41.6 fb<sup>-1</sup>. Interactions of the long-lived particles in the CMS endcap muon system would create hadronic or electromagnetic showers, producing clusters of detector hits. Selected events contain at least one such high-multiplicity cluster in the muon endcaps and require the presence of a displaced muon. The most stringent upper limits to date on the branching fraction B(B - ΚΦ), where the long-lived particle Φ decays to a pair of hadrons, are obtained for Φ masses of 0.3-3.0 GeV and Φ mean proper decay lengths in the range of 1-500 cm.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
Observation of B_{c}^{+}→Dh^{+}h^{-} Decays.
, Phys Rev Lett, Vol: 136Searches are presented for B_{c}^{+}→Dh^{+}h^{-} decays, where D is a charmed meson and h^{±} is a charged pion or kaon, using pp collision data collected by the LHCb experiment corresponding to an integrated luminosity of 9 fb^{-1}. The decays B_{c}^{+}→D^{+}K^{+}π^{-}, B_{c}^{+}→D^{*+}K^{+}π^{-}, and B_{c}^{+}→D_{s}^{+}K^{+}K^{-} are observed for the first time. Their branching fractions, expressed as ratios relative to that of the B_{c}^{+}→B_{s}^{0}π^{+} decay, are determined to be R(B_{c}^{+}→D^{+}K^{+}π^{-})=(1.96±0.23±0.08±0.10)×10^{-3}, R(B_{c}^{+}→D^{*+}K^{+}π^{-})=(3.67±0.55±0.24±0.20)×10^{-3}, R(B_{c}^{+}→D_{s}^{+}K^{+}K^{-})=(1.61±0.35±0.13±0.07)×10^{-3}, where the first uncertainty is statistical, the second is systematic, and the third is due to the limited precision on the D-meson branching fractions. The decay channels proceed primarily through excited K^{0} or D^{0} resonances or ϕ mesons, and open a new avenue for studies of charge-parity violation in beauty mesons.
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Journal articleHayrapetyan A, Makarenko V, Tumasyan A, et al., 2026,
Simultaneous Probe of the Charm and Bottom Quark Yukawa Couplings Using tt[over ¯]H Events.
, Phys Rev Lett, Vol: 136A search for the standard model Higgs boson decaying to a charm quark-antiquark pair, H→cc[over ¯], produced in association with a top quark-antiquark pair (tt[over ¯]H) is presented. The search is performed with data from proton-proton collisions at sqrt[s]=13 TeV, corresponding to an integrated luminosity of 138 fb^{-1}. Advanced machine learning techniques are employed for jet flavor identification and event classification. The Higgs boson decay to a bottom quark-antiquark pair is measured simultaneously and the observed tt[over ¯]H(H→bb[over ¯]) event rate relative to the standard model expectation is 0.91_{-0.22}^{+0.26}. The observed (expected) upper limit on the product of production cross section and branching fraction σ(tt[over ¯]H)B(H→cc[over ¯]) is 0.11 (0.13) pb at 95% confidence level, corresponding to 7.8 (8.7) times the standard model prediction. When combined with the previous search for H→cc[over ¯] via associated production with a W or Z boson, the observed (expected) 95% confidence interval on the Higgs-charm Yukawa coupling modifier, κ_{c}, is |κ_{c}|<3.5 (2.7), the most stringent constraint to date.
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Journal articleAbubakar S, Acero MA, Acharya B, et al., 2026,
Precision Measurement of Neutrino Oscillation Parameters with 10 Years of Data from the NOvA Experiment.
, Phys Rev Lett, Vol: 136This Letter reports measurements of muon-neutrino disappearance and electron-neutrino appearance and the corresponding antineutrino processes between the two NOvA detectors in the NuMI neutrino beam. These measurements use a dataset with double the neutrino mode beam exposure that was previously analyzed, along with improved simulation and analysis techniques. A joint fit to these samples in the three-flavor paradigm results in the most precise single-experiment constraint on the atmospheric neutrino mass splitting, Δm_{32}^{2}=2.431_{-0.034}^{+0.036}(-2.479_{-0.036}^{+0.036})×10^{-3} eV^{2} if the mass ordering is normal (inverted). In both orderings, a region close to maximal mixing with sin^{2}θ_{23}=0.55_{-0.06}^{+0.02} is preferred. The NOvA data show a mild preference for the normal mass ordering with a Bayes factor of 2.4 (corresponding to 70% of the posterior probability), indicating that the normal ordering is 2.4 times more probable than the inverted ordering. When incorporating a 2D Δm_{32}^{2}-sin^{2}2θ_{13} constraint based on Daya Bay data, this preference strengthens to a Bayes factor of 6.6 (87%).
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Journal articleAbubakar S, Acero MA, Acharya B, et al., 2026,
Explanation of the seasonal variation of cosmic multiple muon events observed with the NOvA Near Detector
, Physical Review D, Vol: 113, ISSN: 2470-0010The flux of cosmic ray muons at the Earth’s surface exhibits seasonal variations due to changes in the temperature of the atmosphere affecting the production and decay of mesons in the upper atmosphere. Using 1473 live days of data collected by the NuMI Off-axis ν<inf>e</inf> Appearance (NOvA) Near Detector during 2018–2022, we studied the seasonal pattern in the multiple-muon event rate. The data confirm an anticorrelation between the multiple-muon event rate and effective atmospheric temperature, consistent across all the years of data. Previous analyses from MINOS and NOvA saw a similar anticorrelation but did not include an explanation. We find that this anticorrelation is driven by altitude–geometry effects as the average muon production height changes with the season. This has been studied with a CORSIKA cosmic ray simulation package by varying atmospheric parameters, and provides an explanation to a longstanding discrepancy between the seasonal phases of single and multiple-muon events.
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Journal articleAbratenko P, Alterkait O, Andrade Aldana D, et al., 2026,
First measurement of differential cross sections for muon neutrino charged current interactions on argon with a two-proton final state using the MicroBooNE detector
, Physics Letters Section B Nuclear Elementary Particle and High Energy Physics, Vol: 872, ISSN: 0370-2693We present the first measurement of differential cross sections for charged-current muon neutrino interactions on argon with one muon, two protons, and no pions in the final state. These final states are dominated by two-nucleon knockout interactions, which are complicated to model and for which there is currently limited information about the characteristics of these interactions in existing neutrino-nucleus scattering data. Detailed investigations of two-nucleon knockout are vital to support upcoming experiments exploring the nature of the neutrino. Among the different kinematic quantities measured, the opening angle between the two protons, the angle between the total proton momentum and the muon, and the total transverse momentum of the final state system are most sensitive to the underlying physics processes as embodied in various theoretical models.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2026,
Measurements of the inclusive W and Z boson production cross sections and their ratios in proton-proton collisions at TeV
, Journal of High Energy Physics, Vol: 2026Measurements are presented of the W and Z boson production cross sections in proton-proton collisions at a center-of-mass energy of 13.6 TeV. Data collected in 2022 and corresponding to an integrated luminosity of 5.01 fb<sup>−1</sup> with one or two identified muons in the final state are analyzed. The results for the products of total inclusive cross sections and branching fractions for muonic decays of W and Z bosons are (acceptance) nb for W<sup>+</sup> boson production, (acceptance) nb for W<sup>−</sup> boson production, and (acceptance) nb for the Z boson production in the dimuon mass range of 60–120 GeV, all with negligible statistical uncertainties. Furthermore, the corresponding fiducial cross sections, as well as cross section ratios for both fiducial and total phase space, are provided. The ratios include charge-separated results for W boson production (W<sup>+</sup> and W<sup>−</sup>) and the sum of the two contributions (W<sup>±</sup>), each relative to the measured Z boson production cross section. Additionally, the ratio of the measured cross sections for W<sup>+</sup> and W<sup>−</sup> boson production is reported. All measurements are in agreement with theoretical predictions, calculated at next-to-next-to-leading order accuracy in quantum chromodynamics.
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Journal articleAlt C, Blanchet A, Bordoni S, et al., 2026,
Modeling scintillation photon transport and reconstruction algorithms for the time-of-flight detector in the T2K neutrino experiment
, Journal of Instrumentation, Vol: 21The T2K ND280 upgrade aims to reduce the systematic uncertainty of the CP-violating phase,δ <inf>CP</inf>, to reject non-CP violation hypothesis at 3σconfidence level. A crucial component of the ND280 upgrade, alongside the Super Fine Grained Detector (SuperFGD) and two High-Angle Time Projection Chambers (TPCs), is the Time-of-Flight (ToF) detector, which significantly enhances background rejection and particle identification capabilities. The ToF detector features six modules in a cube configuration, each with 20 plastic scintillator bars measuring 220×12×1 cm<sup>3</sup>and is equipped with Silicon Photomultiplier (MPPC) arrays at both ends to capture scintillation light. This letter outlines the modelling of the detector response and the signal reconstruction process.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
Measurement of the branching fraction of the Λb0→J/ψΛ decay and isospin asymmetry of B → J/ψK decays
, Journal of High Energy Physics, Vol: 2026This paper describes a measurement of the Λb0→J/ψΛ branching fraction using data collected with the LHCb experiment in proton-proton collisions from 2016 to 2018. The dataset corresponds to an integrated luminosity of 5.4 fb<sup>−1</sup>. The branching fraction is determined relative to that of B0→J/ψKS0 decays, (Formula presented.) yielding BΛb0→J/ψΛ=3.34±0.02±0.10±0.08±0.28×10−4, where the first uncertainty is statistical, the second systematic, the third due to external inputs on branching fractions and the fourth due to the ratio of Λb0 baryon and B<sup>0</sup> meson hadronisation fractions. In addition, the isospin asymmetry between the rates of B0→J/ψKS0 and B<sup>+</sup>→ J/ψK<sup>+</sup> decays is measured to be (Formula presented.) where the first uncertainty is statistical and the second systematic.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2026,
A model-independent measurement of the CKM angle γ in the decays B±→ [K+K−π+π−]Dh± and B±→ [π+π−π+π−]Dh± (h = K, π)
, Journal of High Energy Physics, Vol: 2026A model-independent determination of the CKM angle γ is presented, using the B<sup>±</sup> → [K<sup>+</sup>K<sup>−</sup>π<sup>+</sup>π<sup>−</sup>]<inf>D</inf>h<sup>±</sup> and B<sup>±</sup> → [π<sup>+</sup>π<sup>−</sup>π<sup>+</sup>π<sup>−</sup>]<inf>D</inf>h<sup>±</sup> decays, with h = K, π. This measurement is the first phase-space binned study of these decay modes, and uses a sample of proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb<sup>−1</sup>. The phase-space bins are optimised for sensitivity to γ, and in each bin external inputs from the BESIII experiment are used to constrain the charm strong-phase parameters. The result of this binned analysis is γ=53.9−8.9+9.5°, where the uncertainty includes both statistical and systematic contributions. Furthermore, when combining with existing phase-space integrated measurements of the same decay modes, a value of γ=52.6−6.4+8.5° is obtained, which is one of the most precise determinations of γ to date.
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Journal articleAaij R, Abdelmotteleb ASW, Beteta A, et al., 2026,
Observation and Investigation of the Tcc1(4430)+ Structure in B+ → ψ(2S)K0Sπ+ Decays
, Physical Review D, Vol: 113, ISSN: 2470-0010The first four-dimensional amplitude analysis of the B<sup>+</sup> → ψ(2S)K<sup>0</sup><inf>S</inf>π<sup>+</sup> decay is performed with proton-proton collision data collected by the LHCb experiment at √s = 13 TeV, corresponding to an integrated luminosity of 5.4 fb<sup>−1</sup>. The data cannot be fully explained by B<sup>+</sup> → ψ(2S)K*<sup>+</sup> contributions alone. A significantly better description of the data is obtained by adding a T<sup>+</sup><inf>cc</inf> contribution decaying to ψ(2S)π<sup>+</sup>. The properties of the T<sup>+</sup><inf>cc</inf> structure are consistent with the exotic state T<inf>cc1</inf>(4430)<sup>+</sup> reported in the isospin-related B<sup>0</sup> → ψ(2S)K−π<sup>+</sup> decay. Effects of a possible T<inf>cc1</inf>(4430)<sup>+</sup> → D*<inf>1</inf> (2600)<sup>0</sup>D<sup>+</sup> decay mode on the T<inf>cc1</inf>(4430)<sup>+</sup> → ψ(2S)π<sup>+</sup> mass distribution are investigated through a Flatté parametrization, providing constraints on the relative decay strength. A description of the T<inf>cc1</inf>(4430)<sup>+</sup> structure using the triangle singularity mechanism is studied and also found to be consistent with the data.
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Journal articleZwalinski L, Zou W, Zormpa O, et al., 2026,
Erratum to: Precision measurement of the B0 meson lifetime using B0 → J/ ψ K*0 decays with the ATLAS detector (The European Physical Journal C, (2025), 85, 7, (736), 10.1140/epjc/s10052-025-14232-8)
, European Physical Journal C, Vol: 86, ISSN: 1434-6044When deriving the B0 meson decay width Γd from the measured effective lifetime τB0 formula (1) for the decay of the B0 and B¯0 mesons to the same final state has been used, which included a nonzero asymmetry parameter A. However, since the two mesons decay to flavour specific final states the value of A in this case is zero [1], thus the original formula (1) simplifies to: (Formula presented.) The Γd value published in the original paper (Abstract, Chap. 7 Results, Chap. 8 Conclusions) was Γd=0.6639±0.0005(stat.)±0.0016(syst.)±0.0038(ext.)ps-1. The correct value is Γd=0.6643±0.0005(stat.)±0.0016(syst.)ps-1. In the original paper the external systematic uncertainty was dominated by the uncertainty of the asymmetry parameter A. Since this parameter is not contained in the simplified formula (1’) the uncertainty from external sources, denoted “(ext.)”, now only stems from the parameter y. It no longer shows up in the result, because it is reduced to a negligible level. Furthermore, Γd is used to derive a value for the ratio of decay widths Γd/Γs. The originally published number was Γd/Γs=0.9905±0.0022(stat.)±0.0036(syst.)±0.0057(ext.), while the correct result is Γd/Γs=0.9910±0.0022(stat.)±0.0036(syst.). Due to the smaller total uncertainty of this ratio the new number for the compatibility of the ATLAS result for Γd/Γs with the HQE theory prediction is 1.6σ (was 1.3σ), and the compatibility with the experimental average is 1.7σ (was 1.3σ). All other significances remain as in the original paper.
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Journal articleJung S, Abe K, Asaoka Y, et al., 2026,
Search for nucleon decay via p → νπ+ and n → νπ0 in 0.484 Mton-year of Super-Kamiokande data
, Physical Review D, Vol: 113, ISSN: 2470-0010We present the results of searches for nucleon decays via p → νπ<sup>þ</sup> and n → νπ<sup>0</sup> using a 0.484 Mt · yr exposure of Super-Kamiokande I-V data covering the entire pure water phase of the experiment. Various improvements on the previous 2014 nucleon decay search [Phys. Rev. Lett. 113, 121802 (2014)], which used an exposure of 0.173 Mt · yr, are incorporated. The physics models related to pion production and nuclear interaction are refined with external data, and a more comprehensive set of systematic uncertainties, now including those associated with the atmospheric neutrino flux and pion production channels, is considered. Also, the fiducial volume has been expanded by 21%. No significant indication of a nucleon decay signal is found beyond the expected background. Lower bounds on the nucleon partial lifetimes are determined to be 3.5 × 10<sup>32</sup> yr for p → νπ<sup>þ</sup> and 1.4 × 10<sup>33</sup> yr for n → νπ<sup>0</sup> at 90% confidence level.
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Journal articleAaij R, W Abdelmotteleb AS, Beteta CA, et al., 2026,
Search for K0SðLÞ → π+π−μ+μ− decays at LHCb
, Physical Review D, Vol: 113, ISSN: 2470-0010A search for K<sup>0</sup><inf>S</inf>ðL<inf>Þ</inf> → π<sup>þ</sup>π<sup>−</sup>μ<sup>þ</sup>μ<sup>−</sup> decays is performed using proton-proton collision data collected by the LHCb experiment at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.4 fb<sup>−1</sup>. No K<sup>0</sup><inf>S</inf>ðL<inf>Þ</inf> → π<sup>þ</sup>π<sup>−</sup>μ<sup>þ</sup>μ<sup>−</sup> signals are found and upper limits are set for the first time on the branching fractions BðK<sup>0</sup><inf>S</inf> → π<sup>þ</sup>π<sup>−</sup>μ<sup>þ</sup>μ<sup>−</sup>Þ < 1.4 × 10<sup>−9</sup> and BðK<sup>0</sup><inf>L</inf> → π<sup>þ</sup>π<sup>−</sup>μ<sup>þ</sup>μ<sup>−</sup>Þ < 6.6 × 10<sup>−7</sup>, at the 90% confidence level.
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Journal articleCMSCollaboration, 2026,
Combined effective field theory interpretation of Higgs boson, electroweak vector boson, top quark, and multijet measurements.
, Eur Phys J C Part Fields, Vol: 86, ISSN: 1434-6044Constraints 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 s = 13 Te , corresponding to integrated luminosities of 36.3 or 138 fb - 1 , are chosen to provide sensitivity to a broad set of operators, for which consistent SMEFT predictions can be derived. These are primarily measurements of differential cross sections which are parameterized as functions of the WCs. In measurements targeting t ( t ¯ ) X production, SMEFT effects are modelled at the detector level. Individual constraints on 64 WCs, and constraints on 43 linear combinations of WCs, are obtained.
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Journal articleCMSCollaboration, 2026,
Search for resonances decaying to an anomalous jet and a Higgs boson in proton-proton collisions at s = 13 Te V.
, Eur Phys J C Part Fields, Vol: 86, ISSN: 1434-6044This paper presents a search for new physics through the process where a massive particle, X, decays into a Higgs boson and a second particle, Y. The Higgs boson subsequently decays into a bottom quark-antiquark pair, which is reconstructed as a single large-radius jet. The decay products of Yare also assumed to produce a single large-radius jet. The identification of the Yparticle is enhanced by computing the anomaly score of its candidate jet using an autoencoder, which measures deviations from typical quark- or gluon-induced jets. This allows a simultaneous search for multiple Ydecay scenarios within a single analysis. In the main benchmark process, Yis a scalar particle that decays into a Wboson pair. Two other scalar Ydecay processes are also considered as benchmarks: decays to a light quark-antiquark pair, and decays to a top quark-antiquark pair. A fourth benchmark process considers Yas a hadronically decaying top quark, arising from the decay of a vector-like quark into a top quark and a Higgs boson. Data recorded by the CMS experiment at a center-of-mass energy of 13 Te V in 2016-2018, corresponding to an integrated luminosity of 138 fb - 1 , are analyzed. The search covers Xmasses between 1.4 and 3.0 Te V and Ymasses between 90 and 400 Ge V , with all simulated signals produced in the narrow-width approximation. No significant excess above the standard model background expectation is observed. The most stringent upper limits to date are placed on benchmark signal cross sections for various masses of X and Y particles.
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Journal articleXLZD Collaboration, 2026,
Model-independent searches of new physics in DARWIN with deep learning.
, Eur Phys J C Part Fields, Vol: 86, ISSN: 1434-6044We present a deep learning pipeline to perform a model-independent, likelihood-free search for anomalous (i.e., non-background) events in the proposed next-generation multi-ton scale liquid xenon-based direct detection experiment, DARWIN. We train an anomaly detector comprising a variational autoencoder (VAE) and a classifier on high-dimensional simulated detector response data and construct a 1D anomaly score to reject the background-only hypothesis in the presence of an excess of non-background-like events. We use simulated validation data to determine the power of the method to reject the background-only hypothesis in the presence of a WIMP dark matter signal, without any model-dependent assumption about the nature of the signal. We show that our neural networks learn relevant features of the events from low-level, high-dimensional detector outputs, avoiding lossy and computationally expensive compression into lower-dimensional observables. Our approach is complementary to the usual likelihood-based analysis, in that it reduces the reliance on many of the corrections and cuts that are traditionally part of the analysis chain, with the potential of achieving higher accuracy and significant reduction of analysis time. We envisage the methodology presented in this work augmenting or complementing likelihood-based and other data-driven methods currently utilized in the DARWIN (and in the future, XLZD) analysis pipeline.
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Journal articleAaij R, Abdelmotteleb ASW, Abellan Beteta C, et al., 2025,
First Observation of the Charmless Baryonic Decay B^{+}→Λ[over ¯]pp[over ¯]p.
, Phys Rev Lett, Vol: 135A search for the charmless baryonic decay B^{+}→Λ[over ¯]pp[over ¯]p is performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of 5.4 fb^{-1}. The branching fraction for this decay is measured for the first time relative to that of the topologically similar decay B^{+}→J/ψK^{+}, with J/ψ→Λ[over ¯]pK^{-}. The branching fraction is measured to be B(B^{+}→Λ[over ¯]pp[over ¯]p)=(2.15±0.35±0.12±0.28)×10^{-7}, where the first uncertainty is statistical, the second is systematic, and the third arises from the uncertainty in the normalization channel branching fraction. The CP asymmetry is measured to be A_{CP}=(5.4±15.6±2.4)%, where the uncertainties are statistical and systematic. The background-subtracted invariant-mass distributions of Λ[over ¯]p and p[over ¯]p pairs exhibit pronounced enhancements at both kinematic thresholds, in contrast to a uniform phase-space distribution.
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Journal articleAbe K, Abe S, Akutsu R, et al., 2025,
Results from the T2K Experiment on Neutrino Mixing Including a New Far Detector μ-like Sample.
, Phys Rev Lett, Vol: 135We have made improved measurements of three-flavor neutrino mixing with 19.7(16.3)×10^{20} protons on target in (anti-)neutrino-enhanced beam modes. A new sample of muon-neutrino events with tagged pions has been added at the far detector, as well as new proton and photon-tagged samples at the near detector. Significant improvements have been made to the flux and neutrino interaction modeling. T2K data continue to prefer the normal mass ordering and upper octant of sin^{2}θ_{23} with a near-maximal value of the charge-parity violating phase with best-fit values in the normal ordering of δ_{CP}=-2.18_{-0.47}^{+1.22}, sin^{2}θ_{23}=0.559_{-0.078}^{+0.018} and Δm_{32}^{2}=(+2.506_{-0.052}^{+0.039})×10^{-3} eV^{2}.
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Journal articleChekhovsky V, Hayrapetyan A, Makarenko V, et al., 2025,
Observation of Coherent ϕ(1020) Meson Photoproduction in Ultraperipheral PbPb Collisions at sqrt[s_{NN}]=5.36 TeV.
, Phys Rev Lett, Vol: 135The first observation of coherent ϕ(1020) meson photoproduction off heavy nuclei is presented using ultraperipheral lead-lead collisions at a center-of-mass energy per nucleon pair of 5.36 TeV. The data were collected by the CMS experiment and correspond to an integrated luminosity of 1.62 μb^{-1}. The ϕ(1020) meson signals are reconstructed via the K^{+}K^{-} decay channel. The production cross section is presented as a function of the ϕ(1020) meson rapidity in the range 0.3<|y|<1.0, probing gluons that carry a fraction of the nucleon momentum (x) around 10^{-4}. The observed cross section exhibits little dependence on rapidity and is significantly suppressed, by a factor of ∼5, compared to a baseline model that treats a nucleus as a collection of free nucleons. Theoretical models that incorporate the nuclear shadowing effect generally provide a better description of the ϕ(1020) data than those incorporating gluon saturation. This study establishes a powerful new tool for exploring nuclear effects and nuclear gluonic structure in the small-x regime at a unique energy scale bridging the perturbative and nonperturbative quantum chromodynamics domains.
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Conference paperAlden N, Ali S, Allison P, et al., 2025,
Advancing ARA: the Next-Generation (ARA-Next) DAQ System
The Askaryan Radio Array (ARA) has been operating at the South Pole for over a decade, searching for ultra-high-energy astrophysical and cosmogenic neutrinos using the Askaryan effect. ARA has consistently served as a testbed for innovative trigger designs and advancing electronic upgrades, with ongoing data acquisition (DAQ) improvements over the past 2–3 years and a long-term plan to transition to Radio Frequency System-on-Chip (RFSoC) technology. This upgrade enables real-time data processing and sophisticated triggers, enhancing efficiency by identifying double pulses from in-ice neutrino interactions, using templates for cosmic rays, searching for real-time coincidences with the IceCube detector observations, and filtering anthropogenic noise through directional analysis. In 2024, two of the five ARA stations received DAQ upgrades, improving the existing electronics, with RFSoC-based DAQ foreseen in the coming years. In this proceedings contribution, recent ARA activities are presented, with emphasis on the planned ARA-Next trigger strategies involving RFSoC technology and the 2024–2025 season upgrades of the existing ATRI-based DAQ system to its revised version.
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