Search for the lepton-flavor violating decay Bs0 → ϕμ±τ∓

A search for the lepton-flavor violating decays B0 s → ϕμ±τ∓ is presented, using a sample of proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9 fb−1. The τ leptons are selected using decays with three charged pions. No significant excess is observed, and an upper limit on the branching fraction is determined to be B(B0 s → ϕμ±τ∓) < 1.0 × 10−5 at 90% confidence level

Transverse polarization measurement of Λ hyperons in pNe collisions at √sNN = 68.4 GeV with the LHCb detector

A measurement of the transverse polarization of the Λ andΛ hyperons in pNe fixed-target collisions at √ sNN = 68.4 GeV is presented using data collected by the LHCb detector. The polarization is studied using the decay Λ → pπ− together with its charge conjugated process, the integrated values measured are PΛ = 0.029 ± 0.019 (stat) ± 0.012 (syst), PΛ = 0.003 ± 0.023 (stat) ± 0.014 (syst). Furthermore, the results are shown as a function of the Feynman x variable, transverse momentum, pseudorapidity and rapidity of the hyperons, and are compared with previous measurements

Study of b-hadron decays to Λc^+h-h' final states

Decays of Ξ − b and Ω − b baryons to Λ + c h −h ′− final states, with h −h ′− being π −π −, K−π\ud − and K−K− meson pairs, are searched for using data collected with the LHCb detector. The data sample studied corresponds to an integrated luminosity of 8.7 fb−1 of pp collisions collected at centre-of-mass energies √ s = 7, 8 and 13 TeV. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the B− → Λ + c pπ− mode, are measured, with Ξ − b → Λ + c K−π −, Ξ − b → Λ + c K−K− and Ω − b → Λ + c K−K− decays being observed at over 5 σ significance. The Ξ − b → Λ + c K−π − mode is also used to measure the Ξ − b production asymmetry, which is found to be consistent with zero. In addition, the B− → Λ + c pK− decay is observed for the first time, and its branching fraction is measured relative to that of the B− → Λ + c pπ− mode

Precision measurement of the Ξb− baryon lifetime

A sample of pp collision data, corresponding to an integrated luminosity of 5.5 fb−1 and collected by the LHCb experiment during LHC Run 2, is used to measure the ratio of the lifetime of the Ξ− b baryon to that of the Λ0 b baryon, rτ ≡ τΞ− b =τΛ0 b . The value rτ = 1.076 0.013 0.006 is obtained, where the first uncertainty is statistical and the second systematic. This value is averaged with the corresponding value from Run 1 to obtain rRun 1;2 τ = 1.078 0.012 0.007. Multiplying by the world-average value of the Λ0 b lifetime yields τ Run 1;2 Ξ− b = 1.578 0.018 0.010 0.011 ps, where the uncertainties are statistical, systematic, and due to the limited knowledge of the Λ0 b lifetime. This measurement improves the precision of the current world average of the Ξ− b lifetime by about a factor of 2, and is in good agreement with the most recent theoretical predictions

Observation of muonic Dalitz decays of chib mesons and precise spectroscopy of hidden-beauty states

The decays of the χb1(1P), χb2(1P), χb1(2P) and χb2(2P) mesons into the Υ(1S)µ +µ − final state are observed with a high significance using proton-proton collision data collected with the LHCb detector and corresponding to an integrated luminosity of 9 fb−1 . The newly observed decays together with the Υ(2S) → Υ(1S)π +π − and Υ(3S) → Υ(2S)π +π − decay modes are used for precision measurements of the mass and mass splittings for the hidden-beauty states

Study of b-hadron decays to Λc+h−h′− final states

Decays of Ξb− and Ωb− baryons to Λc+h−h′− final states, with h−h′− being π−π−, K−π− and K−K− meson pairs, are searched for using data collected with the LHCb detector. The data sample studied corresponds to an integrated luminosity of 8.7 fb−1 of pp collisions collected at centre-of-mass energies s = 7, 8 and 13 TeV. The products of the relative branching fractions and fragmentation fractions for each signal mode, relative to the B−→Λc+p ̄π− mode, are measured, with Ξb−→Λc+K−π−, Ξb−→Λc+K−K− and Ωb−→Λc+K−K− decays being observed at over 5 σ significance. The Ξb−→Λc+K−π− mode is also used to measure the Ξb− production asymmetry, which is found to be consistent with zero. In addition, the B−→Λc+p ̄K− decay is observed for the first time, and its branching fraction is measured relative to that of the B−→Λc+p ̄π− mode

Search for Time-Dependent CP Violation in D0 →π+π-π0 Decays

A measurement of time-dependent CP violation in D0→π+π-π0 decays using a pp collision data sample collected by the LHCb experiment in 2012 and from 2015 to 2018, corresponding to an integrated luminosity of 7.7 fb-1, is presented. The initial flavor of each D0 candidate is determined from the charge of the pion produced in the D∗(2010)+→D0π+ decay. The decay D0→K-π+π0 is used as a control channel to validate the measurement procedure. The gradient of the time-dependent CP asymmetry ΔY in D0→π+π-π0 decays is measured to be ΔY=(-1.3±6.3±2.4)×10-4, where the first uncertainty is statistical and the second is systematic, which is compatible with CP conservation

Search for the rare decay of charmed baryon <math display="inline"><msubsup><mi mathvariant="normal">Λ</mi><mi>c</mi><mo>+</mo></msubsup></math> into the <math display="inline"><mi>p</mi><msup><mi>μ</mi><mo>+</mo></msup><msup><mi>μ</mi><mo>-</mo></msup></math> final state

International audienceA search for the nonresonant Λc+→pμ+μ- decay is performed using proton-proton collision data recorded at a center-of-mass energy of 13 TeV by the LHCb experiment, corresponding to an integrated luminosity of 5.4  fb-1. No evidence for the decay is found in the dimuon invariant-mass regions where the expected contributions of resonances is subdominant. The upper limit on the branching fraction of the Λc+→pμ+μ- decay is determined to be 2.9(3.2)×10-8  at  90%(95%) confidence level. The branching fractions in the dimuon invariant-mass regions dominated by the η, ρ and ω resonances are also determined

Comprehensive analysis of local and nonlocal amplitudes in the B0 → K*0μ+μ− decay

Abstract A comprehensive study of the local and nonlocal amplitudes contributing to the decay B0 → K*0(→ K+π−)μ+μ− is performed by analysing the phase-space distribution of the decay products. The analysis is based on pp collision data corresponding to an integrated luminosity of 8.4 fb−1 collected 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 $${\mathcal{C}}_9$$ C 9 , responsible for vector dimuon currents, exhibits a 2.1σ deviation from the Standard Model expectation. The Wilson Coefficients $${\mathcal{C}}_{10}$$ C 10 , $${\mathcal{C}}_9^{\prime }$$ C 9 ′ and $${\mathcal{C}}_{10}^{\prime }$$ C 10 ′ are all in better agreement than $${\mathcal{C}}_9$$ C 9 with the Standard Model and the global significance is at the level of 1.5σ. The model used also accounts for nonlocal contributions from B0→ K*0[τ+τ−→ μ+μ−] rescattering, resulting in the first direct measurement of the bsττ vector effective-coupling $${\mathcal{C}}_{9\tau }$$ C 9 τ .</jats:p