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Abstract:

The first evidence for the decay B-→D**0τ-ν¯τ is obtained using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb-1, at centre-of-mass energies of 7, 8, and 13 TeV. Here, the D**0 meson represents any of the three excited charm mesons D1(2420)0, D2*(2460)0, and D1′(2400)0. The B-→D**0τ-ν¯τ signal is measured with a significance of 3.5σ, including systematic uncertainties. The combined branching fraction B(B-→D1,2**0τ-ν¯τ)×B(D1,2**0→D*+π-), where D1,2**0 denotes both D1(2420)0 and D2*(2460)0 contributions, is measured to be [0.051±0.013(stat)±0.006(syst)±0.009(ext)]%, where the last uncertainty reflects that of the branching fraction of the normalization channel B-→D1,2**0Ds-(*). The ratio between the tauonic and muonic semileptonic B decays, with the latter taken from world average values, is also determined and found to be R(D1,2**0)=0.13±0.03(stat)±0.01(syst)±0.02(ext).

Abstract:

A study of the charmless baryonic decays Bs0→K0pp¯ is presented, where Bs0 denotes either a B0 or a Bs0 meson. The analysis is based on proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8, and 13 TeV, corresponding to an integrated luminosity of 9 fb−1. The decay Bs0→K0pp¯ is observed for the first time, with a measured branching fraction of (9.14 ± 1.69 ± 0.90 ± 0.33 ± 0.20) × 10−7 and a significance of 5.6σ. The uncertainties respectively account for statistical and systematic contributions, the precision of the branching fraction of the normalisation channel B0→ K0π+π− and the fragmentation fraction ratio fs/fd. The branching fraction determined for B0→K0pp¯ is (2.82 ± 0.08 ± 0.12 ± 0.10) × 10−6, which is the most precise measurement to date.

Abstract:

An angular analysis of the decay Bs0→ ϕe+e− is presented, using proton-proton collision data collected with the LHCb detector between 2011 and 2018 at centre-of-mass energies of 7, 8 and 13 TeV. The combined dataset corresponds to an integrated luminosity of 9 fb−1. Observables are determined by fitting time-integrated projections of the angular distribution in three bins of dielectron mass squared, q2, corresponding to [0.1, 1.1], [1.1, 6.0] and [15.0, 19.0] GeV2/c4. The results are compatible with predictions based on the Standard Model of particle physics.

Abstract:

A first determination of the strong-phase difference between $D^0$ and $\stackrel{¯}{D^0}→K^{+}{K}^{−}{\mathrm{Ï€}}^{+}{\mathrm{Ï€}}^{−}$ is performed using $e^{+}{e}^{−}→\mathrm{ψ}(3770)→D\stackrel{¯}{D}$ data collected by the BESIII detector corresponding to an integrated luminosity of $20.3{\mathrm{fb}}^{−1}$ . The measurements are made in four pairs of bins in phase space, which are chosen to provide optimal sensitivity to the angle $\mathrm{γ}$ of the unitarity triangle in $B^{Â\pm }→D{K}^{Â\pm }$ decays. From these measurements, it follows that the $CP$ -even fraction of the decay is $F_{+}=0.754Â\pm 0.010_{\mathrm{stat}}Â\pm 0.008_{\mathrm{syst}}$ . In addition, the branching fraction of $D^0→K^{+}{K}^{−}{\mathrm{Ï€}}^{+}{\mathrm{Ï€}}^{−}$ is measured to be $(2.863Â\pm 0.028_{\mathrm{stat}}Â\pm 0.045_{\mathrm{syst}})×{10}^{−3}$ , which is twice as precise as previous results obtained at other experiments. Published by the American Physical Society 2025