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Abstract:

This paper describes a measurement of the Âìb0→J/ψÂì branching fraction using data collected with the LHCb experiment in proton-proton collisions from 2016 to 2018. The dataset corresponds to an integrated luminosity of 5.4 fb−1. The branching fraction is determined relative to that of B0→J/ψKS0 decays,BÂìb0→J/ψÂìBB0→J/ψKS0=0.750±0.005±0.022±0.005±0.062, yielding BÂìb0→J/ψÂì=3.34±0.02±0.10±0.08±0.28×10−4, where the first uncertainty is statistical, the second systematic, the third due to external inputs on branching fractions and the fourth due to the ratio of Âìb0 baryon and B0 meson hadronisation fractions. In addition, the isospin asymmetry between the rates of B0→J/ψKS0 and B+→ J/ψK+ decays is measured to beAI=−0.0135±0.0004±0.0133, where the first uncertainty is statistical and the second systematic.

Abstract:

An amplitude analysis of the $B^{+}→({\mathrm{Ï€}}^{+}{\mathrm{Ï€}}^{−})(K_{\mathrm{S}}^0{\mathrm{Ï€}}^{+})$ decay is performed in the mass regions $0.30<m_{{\mathrm{Ï€}}^{+}{\mathrm{Ï€}}^{−}}<1.10\mathrm{GeV}/c^2$ and $0.75<m_{K_{\mathrm{S}}^0{\mathrm{Ï€}}^{+}}<1.20\mathrm{GeV}/c^2$ , using $pp$ collision data recorded with the LHCb detector corresponding to an integrated luminosity of $9{\mathrm{fb}}^{−1}$ . The polarization fractions and $CP$ asymmetries for $B^{+}→\mathrm{ÒÏ}(770{)}^0{K}^{*}(892{)}^{+}$ decays are measured. Violation of the $CP$ symmetry in the decay $B^{+}→\mathrm{ÒÏ}(770{)}^0{K}^{*}(892{)}^{+}$ is observed for the first time, with a significance exceeding 9 standard deviations. The $CP$ asymmetry is measured to be ${\mathcal{A}}_{CP}=0.507Â\pm 0.062(\mathrm{stat})Â\pm 0.024(\mathrm{syst})$ and the $CP$ -averaged longitudinal polarization fraction of $f_L=0.720Â\pm 0.028(\mathrm{stat})Â\pm 0.009(\mathrm{syst})$ . The measurements help to shed light on the polarization puzzle of $B$ mesons decaying to two vector mesons.

Abstract:

Searches are presented for $B_c^{+}→D{h}^{+}{h}^{−}$ decays, where $D$ is a charmed meson and $h^{Â\pm }$ is a charged pion or kaon, using $pp$ collision data collected by the LHCb experiment corresponding to an integrated luminosity of $9{\mathrm{fb}}^{−1}$ . The decays $B_c^{+}→D^{+}{K}^{+}{\mathrm{Ï€}}^{−}$ , $B_c^{+}→D^{*+}{K}^{+}{\mathrm{Ï€}}^{−}$ , and $B_c^{+}→D_s^{+}{K}^{+}{K}^{−}$ are observed for the first time. Their branching fractions, expressed as ratios relative to that of the $B_c^{+}→B_s^0{\mathrm{Ï€}}^{+}$ decay, are determined to be $\mathcal{R}(B_c^{+}→D^{+}{K}^{+}{\mathrm{Ï€}}^{−})=(1.96Â\pm 0.23Â\pm 0.08Â\pm 0.10)×{10}^{−3}$ , $\mathcal{R}(B_c^{+}→D^{*+}{K}^{+}{\mathrm{Ï€}}^{−})=(3.67Â\pm 0.55Â\pm 0.24Â\pm 0.20)×{10}^{−3}$ , $\mathcal{R}(B_c^{+}→D_s^{+}{K}^{+}{K}^{−})=(1.61Â\pm 0.35Â\pm 0.13Â\pm 0.07)×{10}^{−3}$ , where the first uncertainty is statistical, the second is systematic, and the third is due to the limited precision on the $D$ -meson branching fractions. The decay channels proceed primarily through excited $K^0$ or $D^0$ resonances or $\mathrm{Ï•}$ mesons, and open a new avenue for studies of charge-parity violation in beauty mesons.

Abstract:

A model-independent determination of the CKM angle γ is presented, using the B± → [K+K−π+π−]Dh± and B± → [π+π−π+π−]Dh± decays, with h = K, π. This measurement is the first phase-space binned study of these decay modes, and uses a sample of proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The phase-space bins are optimised for sensitivity to γ, and in each bin external inputs from the BESIII experiment are used to constrain the charm strong-phase parameters. The result of this binned analysis is γ=53.9−8.9+9.5°, where the uncertainty includes both statistical and systematic contributions. Furthermore, when combining with existing phase-space integrated measurements of the same decay modes, a value of γ=52.6−6.4+8.5° is obtained, which is one of the most precise determinations of γ to date.

Abstract:

A search for the charmless baryonic decay $B^{+}→\stackrel{¯}{\mathrm{Âì}}p\stackrel{¯}{p}p$ is performed using proton-proton collision data recorded by the LHCb experiment, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{−1}$ . The branching fraction for this decay is measured for the first time relative to that of the topologically similar decay $B^{+}→J/\mathrm{ψ}{K}^{+}$ , with $J/\mathrm{ψ}→\stackrel{¯}{\mathrm{Âì}}p{K}^{−}$ . The branching fraction is measured to be $\mathcal{B}(B^{+}→\stackrel{¯}{\mathrm{Âì}}p\stackrel{¯}{p}p)=(2.15Â\pm 0.35Â\pm 0.12Â\pm 0.28)×{10}^{−7}$ , where the first uncertainty is statistical, the second is systematic, and the third arises from the uncertainty in the normalization channel branching fraction. The $CP$ asymmetry is measured to be ${\mathcal{A}}_{CP}=(5.4Â\pm 15.6Â\pm 2.4)\%$ , where the uncertainties are statistical and systematic. The background-subtracted invariant-mass distributions of $\stackrel{¯}{\mathrm{Âì}}p$ and $\stackrel{¯}{p}p$ pairs exhibit pronounced enhancements at both kinematic thresholds, in contrast to a uniform phase-space distribution.