The branching fraction of the rare Bs0 → ϕ μ+μ− decay is measured using data collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to integrated luminosities ...of 1, 2, and 6 fb−1 , respectively. The branching fraction is reported in intervals of q2, the square of the dimuon invariant mass. In the q2 region between 1.1 and 6.0 GeV2/ c4, the measurement is found to lie 3.6 standard deviations below a standard model prediction based on a combination of light cone sum rule and lattice QCD calculations. In addition, the first observation of the rare Bs0 → f2′ ( 1525 ) μ+μ− decay is reported with a statistical significance of 9 standard deviations and its branching fraction is determined.
A measurement of the C P asymmetry in D0 → K0SK0S decays is reported, based on a data sample of proton-proton collisions collected by the LHCb experiment from 2015 to 2018, corresponding to an ...integrated luminosity of 6 fb−1. The flavor of the D0 candidate is determined using the charge of the D*± meson, from which the decay is required to originate. The D0 → K+K− decay is used as a calibration channel. The time-integrated CP asymmetry for the D0 → K0SK0S mode is measured to be A CP (D0 → K0SK0S) = (−3.1 ± 1.2 ± 0.4 ± 0.2), where the first uncertainty is statistical, the second is systematic, and the third is due to the uncertainty on the C P asymmetry of the calibration channel. This is the most precise determination of this quantity to date.
The ratio of the B0s and B0 fragmentation fractions, fs/fd, in proton-proton collisions at the LHC, is obtained as a function of B -meson transverse momentum and collision center-of-mass energy from ...the combined analysis of different B-decay channels measured by the LHCb experiment. The results are described by a linear function of the meson transverse momentum or with a function inspired by Tsallis statistics. Precise measurements of the branching fractions of the B0s → J/ψϕ and B0s → D−s π+ decays are performed, reducing their uncertainty by about a factor of 2 with respect to previous world averages. Numerous B0s decay branching fractions, measured at the LHCb experiment, are also updated using the new values of fs/fd and branching fractions of normalization channels. These results reduce a major source of systematic uncertainty in several searches for new physics performed through measurements of B0s branching fractions.
Upgrades to the LHCb computing infrastructure in the first long shutdown of the LHC have allowed for high quality decay information to be calculated by the software trigger making a separate offline ...event reconstruction unnecessary. Furthermore, the storage space of the triggered candidate is an order of magnitude smaller than the entire raw event that would otherwise need to be persisted. Tesla is an application designed to process the information calculated by the trigger, with the resulting output used to directly perform physics measurements.
A measurement of CP violation in the decay B+ → K+ π0 is reported using data corresponding to an integrated luminosity of 5.4 fb−1 collected with the LHCb experiment at a center-of-mass energy of √s ...= 13 TeV. The CP asymmetry is measured to be 0.025 ± 0.015 ± 0.006 ± 0.003, where the uncertainties are statistical, systematic, and due to an external input. This is the most precise measurement of this quantity. It confirms and significantly enhances the observed anomalous difference between the direct CP asymmetries of the B0 → K+ π− and B+ → K+ π0 decays, known as the K π puzzle.
The first observation of the suppressed semileptonic B0s → K− μ+ νμ decay is reported. Using a data sample recorded in p p collisions in 2012 with the LHCb detector, corresponding to an integrated ...luminosity of 2 fb−1, the branching fraction B(B0s → K−μ+νμ) is measured to be 1.06 ± 0.05 (stat) ± 0.08 (syst) × 10−4, where the first uncertainty is statistical and the second one represents the combined systematic uncertainties. The decay B0s → D−sμ+νμ, where D−s is reconstructed in the final state K+ K−π−, is used as a normalization channel to minimize the experimental systematic uncertainty. Theoretical calculations on the form factors of the B0s → K− and B0s → D−s transitions are employed to determine the ratio of the Cabibbo-Kobayashi-Maskawa matrix elements |Vub|/|Vcb| at low and high B0s → K− momentum transfer.
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