The ratio of the Λ 0 b baryon lifetime to that of the ¯¯¯ B 0 meson is measured using 1.0 fb − 1 of integrated luminosity in 7 TeV center-of-mass energy p p collisions at the LHC. The Λ 0 b ...baryon is observed for the first time in the decay mode Λ 0 b → J / ψ p K − , while the ¯¯¯ B 0 meson decay used is the well known ¯¯¯ B 0 → J / ψ π + K − mode, where the π + K − mass is consistent with that of the ¯¯¯¯ K * 0 ( 892 ) meson. The ratio of lifetimes is measured to be 0.976 ± 0.012 ± 0.006 , in agreement with theoretical expectations based on the heavy quark expansion. Using previous determinations of the ¯¯¯ B 0 meson lifetime, the Λ 0 b lifetime is found to be 1.482 ± 0.018 ± 0.012 ps . In both cases, the first uncertainty is statistical and the second systematic.
A search for the rare decays B 0 s → μ + μ − and B 0 → μ + μ − is performed at the LHCb experiment. The data analyzed correspond to an integrated luminosity of 1 fb − 1 of p p collisions at a ...center-of-mass energy of 7 TeV and 2 fb − 1 at 8 TeV. An excess of B 0 s → μ + μ − signal candidates with respect to the background expectation is seen with a significance of 4.0 standard deviations. A time-integrated branching fraction of B ( B 0 s → μ + μ − ) = ( 2.9 + 1.1 − 1.0 ) × 10 − 9 is obtained and an upper limit of B ( B 0 → μ + μ − ) < 7.4 × 10 − 10 at 95% confidence level is set. These results are consistent with the standard model expectations.
Direct and mixing-induced CP-violating asymmetries in B0s→K+K− decays are measured for the first time using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0 fb−1, ...collected with the LHCb detector at a centre-of-mass energy of 7 TeV. The results are C KK = 0.14 ± 0.11 ± 0.03 and S KK = 0.30 ± 0.12 ± 0.04, where the first uncertainties are statistical and the second systematic. The corresponding quantities are also determined for B 0 → π + π − decays to be C ππ = −0.38 ± 0.15 ± 0.02 and S ππ = −0.71 ± 0.13 ± 0.02, in good agreement with existing measurements.
The results of a search for the rare two-body charmless baryonic decays TeX and TeX are reported. The analysis uses a data sample, corresponding to an integrated luminosity of 0.9 fb−1, of pp ...collision data collected by the LHCb experiment at a centre-of-mass energy of 7 TeV. An excess of TeX candidates with respect to background expectations is seen with a statistical significance of 3.3 standard deviations. This is the first evidence for a two-body charmless baryonic B 0 decay. No significant TeX signal is observed, leading to an improvement of three orders of magnitude over previous bounds. If the excess events are interpreted as signal, the 68.3% confidence level intervals on the branching fractions are $ TeX $ where the first uncertainty is statistical and the second is systematic.
A search for charmless three-body decays of B 0 and B0s mesons with a K0S meson in the final state is performed using the pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, ...collected at a centre-of-mass energy of 7 TeV recorded by the LHCb experiment. Branching fractions of the B0(s)→K0Sh+h′− decay modes (h (′) = π, K), relative to the well measured B0→K0Sπ+π− decay, are obtained. First observation of the decay modes B0s→K0SK±π∓ and B0s→K0Sπ+π− and confirmation of the decay B0→K0SK±π∓ are reported. The following relative branching fraction measurements or limits are obtained $ B(B0→K0SK±π∓)B(B0→K0Sπ+π−)=0.128±0.017(stat.)±0.009(syst.),B(B0→K0SK+K−)B(B0→K0Sπ+π−)=0.385±0.031(stat.)±0.023(syst.),B(B0s→K0Sπ+π−)B(B0→K0Sπ+π−)=0.29±0.06(stat.)±0.03(syst.)±0.02(fs/fd),B(B0s→K0SK±π∓)B(B0→K0Sπ+π−)=1.48±0.12(stat.)±0.08(syst.)±0.12(fs/fd)B(B0s→K0SK+K−)B(B0→K0Sπ+π−)∈0.004;0.068at90%CL.
Prompt production of charmonium χ c0, χ c1 and χ c2 mesons is studied using proton-proton collisions at the LHC at a centre-of-mass energy of TeX TeV. The χ c mesons are identified through their ...decay to J/ψγ, with J/ψ → μ + μ − using photons that converted in the detector. A data sample, corresponding to an integrated luminosity of 1.0 fb−1 collected by the LHCb detector, is used to measure the relative prompt production rate of χ c1 and χ c2 in the rapidity range 2.0 < y < 4.5 as a function of the J/ψ transverse momentum from 3 to 20 GeV/c. First evidence for χ c0 meson production at a high-energy hadron collider is also presented.
Direct and mixing-induced CP-violating asymmetries in B0s→K+K− decays are measured for the first time using a data sample of pp collisions, corresponding to an integrated luminosity of 1.0 fb−1, ...collected with the LHCb detector at a centre-of-mass energy of 7 TeV. The results are C KK = 0.14 ± 0.11 ± 0.03 and S KK = 0.30 ± 0.12 ± 0.04, where the first uncertainties are statistical and the second systematic. The corresponding quantities are also determined for B 0 → π + π − decays to be C ππ = −0.38 ± 0.15 ± 0.02 and S ππ = −0.71 ± 0.13 ± 0.02, in good agreement with existing measurements.
A search for charmless three-body decays of B 0 and B0s mesons with a K0S meson in the final state is performed using the pp collision data, corresponding to an integrated luminosity of 1.0 fb−1, ...collected at a centre-of-mass energy of 7 TeV recorded by the LHCb experiment. Branching fractions of the B0(s)→K0Sh+h′− decay modes (h (′) = π, K), relative to the well measured B0→K0Sπ+π− decay, are obtained. First observation of the decay modes B0s→K0SK±π∓ and B0s→K0Sπ+π− and confirmation of the decay B0→K0SK±π∓ are reported. The following relative branching fraction measurements or limits are obtained $ B(B0→K0SK±π∓)B(B0→K0Sπ+π−)=0.128±0.017(stat.)±0.009(syst.),B(B0→K0SK+K−)B(B0→K0Sπ+π−)=0.385±0.031(stat.)±0.023(syst.),B(B0s→K0Sπ+π−)B(B0→K0Sπ+π−)=0.29±0.06(stat.)±0.03(syst.)±0.02(fs/fd),B(B0s→K0SK±π∓)B(B0→K0Sπ+π−)=1.48±0.12(stat.)±0.08(syst.)±0.12(fs/fd)B(B0s→K0SK+K−)B(B0→K0Sπ+π−)∈0.004;0.068at90%CL.
A first flavor-tagged measurement of the time-dependent C P -violating asymmetry in B 0 s → ϕ ϕ decays is presented. In this decay channel, the C P -violating weak phase arises due to C P violation ...in the interference between B 0 s − ¯¯¯ B 0 s mixing and the b → s ¯ s s gluonic penguin decay amplitude. Using a sample of p p collision data corresponding to an integrated luminosity of 1.0 fb − 1 and collected at a center-of-mass energy of 7 TeV with the LHCb detector, 880 B 0 s → ϕ ϕ signal decays are obtained. The C P -violating phase is measured to be in the interval − 2.46 , − 0.76 rad at a 68% confidence level. The p value of the standard model prediction is 16%.
Using p p collision data corresponding to an integrated luminosity of 1.0 fb − 1 and collected by LHCb in 2011 at a center-of-mass energy of 7 TeV, we report the measurement of direct C P ...violation in B 0 s → K − π + decays, A C P ( B 0 s → K − π + ) = 0.27 ± 0.04 ( stat ) ± 0.01 ( syst ) , with significance exceeding 5 standard deviations. This is the first observation of C P violation in the decays of B 0 s mesons. Furthermore, we provide an improved determination of direct C P violation in B 0 → K + π − decays, A C P ( B 0 → K + π − ) = − 0.080 ± 0.007 ( stat ) ± 0.003 ( syst ) , which is the most precise measurement of this quantity to date.
