ProtoDUNE Single-Phase (ProtoDUNE-SP) is a 770-ton liquid argon time projection chamber that operated in a hadron test beam at the CERN Neutrino Platform in 2018. We present a measurement of the total inelastic cross section of charged kaons on argon as a function of kaon energy using 6 andbeam momentum settings. The flux-weighted average of the extracted inelastic cross section at each beam momentum setting was measured to befor thesetting andfor thesetting.
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Published by the American Physical Society 2024 Free, publicly-accessible full text available November 1, 2025 -
A bstract A comprehensive study of the local and nonlocal amplitudes contributing to the decay
B 0→K *0(→K +π − )μ +μ − is performed by analysing the phase-space distribution of the decay products. The analysis is based onpp collision data corresponding to an integrated luminosity of 8.4 fb− 1collected by the LHCb experiment. This measurement employs for the first time a model of both one-particle and two-particle nonlocal amplitudes, and utilises the complete dimuon mass spectrum without any veto regions around the narrow charmonium resonances. In this way it is possible to explicitly isolate the local and nonlocal contributions and capture the interference between them. The results show that interference with nonlocal contributions, although larger than predicted, only has a minor impact on the Wilson Coefficients determined from the fit to the data. For the local contributions, the Wilson Coefficient , responsible for vector dimuon currents, exhibits a 2.1$$ {\mathcal{C}}_9 $$ σ deviation from the Standard Model expectation. The Wilson Coefficients ,$$ {\mathcal{C}}_{10} $$ and$$ {\mathcal{C}}_9^{\prime } $$ are all in better agreement than$$ {\mathcal{C}}_{10}^{\prime } $$ with the Standard Model and the global significance is at the level of 1.5$$ {\mathcal{C}}_9 $$ σ . The model used also accounts for nonlocal contributions fromB 0→ K *0[τ +τ − → μ +μ − ] rescattering, resulting in the first direct measurement of thebsττ vector effective-coupling .$$ {\mathcal{C}}_{9\tau } $$ Free, publicly-accessible full text available September 1, 2025 -
A search for hidden-charm pentaquark states decaying to a range ofandfinal states, as well as doubly charmed pentaquark states toand, is made using samples of proton-proton collision data corresponding to an integrated luminosity ofrecorded by the LHCb detector at. Since no significant signals are found, upper limits are set on the pentaquark yields relative to that of thebaryon in thedecay mode. The known pentaquark states are also investigated, and their signal yields are found to be consistent with zero in all cases.
© 2024 CERN, for the LHCb Collaboration 2024 CERN Free, publicly-accessible full text available August 1, 2025 -
A bstract A search for the fully reconstructed
$$ {B}_s^0 $$ → μ +μ − γ decay is performed at the LHCb experiment using proton-proton collisions at = 13 TeV corresponding to an integrated luminosity of 5$$ \sqrt{s} $$ . 4 fb− 1. No significant signal is found and upper limits on the branching fraction in intervals of the dimuon mass are set$$ {\displaystyle \begin{array}{cc}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[2{m}_{\mu },1.70\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<7.7\times {10}^{-8},&\ m\left({\mu}^{+}{\mu}^{-}\right)\in \left[\textrm{1.70,2.88}\right]\textrm{GeV}/{c}^2,\\ {}\mathcal{B}\left({B}_s^0\to {\mu}^{+}{\mu}^{-}\gamma \right)<4.2\times {10}^{-8},& m\left({\mu}^{+}{\mu}^{-}\right)\in \left[3.92,{m}_{B_s^0}\right]\textrm{GeV}/{c}^2,\end{array}} $$ at 95% confidence level. Additionally, upper limits are set on the branching fraction in the [2
m μ , 1. 70] GeV/c 2dimuon mass region excluding the contribution from the intermediateϕ (1020) meson, and in the region combining all dimuon-mass intervals.Free, publicly-accessible full text available July 1, 2025 -
The LHCb upgrade represents a major change of the experiment. The detectors have been almost completely renewed to allow running at an instantaneous luminosity five times larger than that of the previous running periods. Readout of all detectors into an all-software trigger is central to the new design, facilitating the reconstruction of events at the maximum LHC interaction rate, and their selection in real time. The experiment's tracking system has been completely upgraded with a new pixel vertex detector, a silicon tracker upstream of the dipole magnet and three scintillating fibre tracking stations downstream of the magnet. The whole photon detection system of the RICH detectors has been renewed and the readout electronics of the calorimeter and muon systems have been fully overhauled. The first stage of the all-software trigger is implemented on a GPU farm. The output of the trigger provides a combination of totally reconstructed physics objects, such as tracks and vertices, ready for final analysis, and of entire events which need further offline reprocessing. This scheme required a complete revision of the computing model and rewriting of the experiment's software.more » « lessFree, publicly-accessible full text available May 1, 2025
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The production of 𝜂 and 𝜂′ mesons is studied in proton-proton and proton-lead collisions collected with the LHCb detector. Proton-proton collisions are studied at center-of-mass energies of 5.02 and 13TeV and proton-lead collisions are studied at a center-of-mass energy per nucleon of 8.16TeV. The studies are performed in center-of-mass (c.m.) rapidity regions 2.5<𝑦c.m.<3.5 (forward rapidity) and −4.0<𝑦c.m.<−3.0 (backward rapidity) defined relative to the proton beam direction. The 𝜂 and 𝜂′ production cross sections are measured differentially as a function of transverse momentum for 1.5<𝑝T<10GeV and 3<𝑝T<10GeV, respectively. The differential cross sections are used to calculate nuclear modification factors. The nuclear modification factors for 𝜂 and 𝜂′ mesons agree at both forward and backward rapidity, showing no significant evidence of mass dependence. The differential cross sections of 𝜂 mesons are also used to calculate 𝜂/𝜋0 cross-section ratios, which show evidence of a deviation from the world average. These studies offer new constraints on mass-dependent nuclear effects in heavy-ion collisions, as well as 𝜂 and 𝜂′ meson fragmentation.more » « lessFree, publicly-accessible full text available February 1, 2025
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Garisto, R (Ed.)The ratios of branching fractions R(D*)= B(B0 --> D*+tau- nu(bar))/ B(B0--> D*+mu- nu(bar)) and R(D)= B(B0 --> D0tau- nu(bar))/ B(B0 --> D0mu- nu(bar)) are measured, assuming isospin symmetry, using a sample of proton-proton collision data corresponding to 3.0 fb−1 of integrated luminosity recorded by the LHCb experiment during 2011 and 2012. The tau lepton is identified in the decay mode τ− → μ−ντν¯μ. The measured values are R*D*)= 0.281+/- 0.018+/- 0.024 and R(D0)=0.441+/- 0.060+/- 0.066, where the first uncertainty is statistical and the second is systematic. The correlation between these measurements is ρ= −0.43. The results are consistent with the current average of these quantities and are at a combined 1.9 standard deviations from the predictions based on lepton flavor universality in the standard modelmore » « less