Amplitude analysis of the radiative decay Bs0 → K+K−γ

A search for radiative decay of B0 s mesons to orbitally excited K+K− states is performed using proton proton collisions recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1 . The dikaon spectrum in the mass range mKK < 2400 MeV/c 2 is dominated by the ϕ(1020) resonance that accounts for almost 70% of the decay rate. Considering the possible contributions of f2(1270), f ′ 2 (1525) and f2(2010) meson states, the overall tensor contribution to the amplitude is measured to be F{f2} = 16.8 ± 0.5 (stat.) ± 0.7 (syst.)%, mostly dominated by the f ′ 2 (1525) state. Several statistically equivalent solutions are obtained for the detailed resonant structure depending on whether the smaller amplitudes interfere destructively or constructively with the dominant amplitude. The preferred solution that corresponds to the lowest values of the ft fractions along with constructive interference leads to the relative branching ratio measurement B(B0 s → f ′ 2γ) B(B0 s → ϕγ) = 19.4 +0.9 −0.8 (stat.) +1.4 −0.5 (syst.) ± 0.5 (B)%, where the last uncertainty is due to the ratio of measured branching fractions to the K+K− final state. This result represents the first observation of the radiative B0 s → f ′ 2 (1525)γ decay, which is the second radiative transition observed in the B0 s sector

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

Amplitude analysis of the radiative decay Bs0→ K+K−γ

A search for radiative decay of Bs0 mesons to orbitally excited K+K− states is performed using proton proton collisions recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The dikaon spectrum in the mass range mKK < 2400 MeV/c2 is dominated by the φ(1020) resonance that accounts for almost 70% of the decay rate. Considering the possible contributions of f2(1270), f2′(1525) and f2(2010) meson states, the overall tensor contribution to the amplitude is measured to be (Formula presented.) mostly dominated by the f2′(1525) state. Several statistically equivalent solutions are obtained for the detailed resonant structure depending on whether the smaller amplitudes interfere destructively or constructively with the dominant amplitude. The preferred solution that corresponds to the lowest values of the fit fractions along with constructive interference leads to the relative branching ratio measurement (Formula presented.) where the last uncertainty is due to the ratio of measured branching fractions to the K+K− final state. This result represents the first observation of the radiative Bs0→f2′1525γ decay, which is the second radiative transition observed in the Bs0 sector