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Abstract:

Measurements of the combined CP asymmetries in B¯0→Ds−D+$$ {\overline{B}}^0\to {D}_s^{-}{D}^{+} $$ and B¯s0→Ds−D−$$ {\overline{B}}_s^0\to {D}_s^{-}{D}^{-} $$ decays are made using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The measurements are found to beACPB¯0→Ds−D+=0.0009±0.0053±0.0040,ACPB¯s0→Ds−D−=0.103±0.053±0.010,$$ {\displaystyle \begin{array}{l}{A}_{CP}\left({\overline{B}}^0\to {D}_s^{-}{D}^{+}\right)=0.0009\pm 0.0053\pm 0.0040,\\ {}{A}_{CP}\left({\overline{B}}_s^0\to {D}_s^{-}{D}^{-}\right)=0.103\pm 0.053\pm 0.010,\end{array}} $$where the first and second uncertainties are statistical and systematic, respectively. This is the first measurement of this asymmetry in B¯s0$$ {\overline{B}}_s^0 $$ decays, and the most precise measurement to date for B¯0$$ {\overline{B}}^0 $$ decays. Both measurements are found to be consistent with CP symmetry.

Abstract:

A measurement of the CKM angle γ using the decay channels B±→ DK± and B±→ Dπ±, where the D meson decays to D→KS0π+π−$$ D\to {K}_{\mathrm{S}}^0{\pi}^{+}{\pi}^{-} $$ or D→KS0K+K−$$ D\to {K}_{\mathrm{S}}^0{K}^{+}{K}^{-} $$, is performed with a data sample corresponding to an integrated luminosity of 5.8 fb−1, collected during 2024 by the upgraded LHCb experiment. CP violation is observed through a difference in the distributions of the Dalitz plot of the D decay between the B+ and B− mesons. The CKM angle γ is determined to be γ = (68.1 ± 6.7)°. Other parameters related to the examined B meson decay modes are also measured. This is the first measurement of the CKM angle γ using the upgraded LHCb detector.

Abstract:

A search for the charmless purely baryonic decay Âìb0→Âìpp¯$$ {\Lambda}_b^0\to \Lambda p\overline{p} $$ is performed using proton-proton collision data recorded by the LHCb experiment at a centre-of-mass energy of s=13$$ \sqrt{s}=13 $$ TeV and corresponding to an integrated luminosity of 6.0 fb−1. The signal decay is observed with a significance of 5.1 standard deviations. Its branching fraction is measured for the first time, relative to that of the topologically similar decay Âìb0→ÂìK+K−$$ {\Lambda}_b^0\to \Lambda {K}^{+}{K}^{-} $$. Contributions from intermediate charmonium resonances decaying to the pp¯$$ p\overline{p} $$ and K+K− final states are explicitly excluded with a requirement on the invariant mass of the companion hadron system, mhh¯<2.85$$ m\left(h\overline{h}\right)<2.85 $$ GeV, where h stands for a proton or a charged kaon. The relative branching fraction is found to beBÂìb0→Âìpp¯BÂìb0→ÂìK+K−=5.1±1.3stat±0.3syst×10−2.$$ \frac{\mathcal{B}\left({\Lambda}_b^0\to \Lambda p\overline{p}\right)}{\mathcal{B}\left({\Lambda}_b^0\to \Lambda {K}^{+}{K}^{-}\right)}=\left(5.1\pm {1.3}_{\left(\mathrm{stat}\right)}\pm {0.3}_{\left(\mathrm{syst}\right)}\right)\times {10}^{-2}. $$

Abstract:

This paper presents the first measurement of the forward-backward asymmetry, AFB, and the flat term, FH, that parameterise the angular distribution of the B+ → π+μ+μ− decay. The proton-proton collision dataset used in the analysis corresponds to an integrated luminosity of 9 fb−1, collected with the LHCb experiment between 2011 and 2018. The analysis is performed in two intervals of dimuon mass squared, one above and one below the region containing the J/ψ and ψ(2S) narrow charmonium resonances. The Standard Model predictions lie within the obtained 68% confidence level interval in the high-mass and within the 99% interval in the low-mass region.

Abstract:

A search for the rare decay $B^{+}→\stackrel{¯}{\mathrm{Âì}}p{\mathrm{μ}}^{+}{\mathrm{μ}}^{−}$ is performed using proton-proton collision data recorded by the LHCb experiment at a center-of-mass energy of $\sqrt{s}=13\mathrm{TeV}$ , corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{−1}$ . An excess of events is found with respect to the background-only expectation, with a signal significance of 3.5 standard deviations, in the low invariant-mass region of $m(\stackrel{¯}{\mathrm{Âì}}p)<2.8\mathrm{GeV}/c^2$ . The branching fraction is measured to be ${\mathcal{B}}_{\mathrm{low}}(B^{+}→\stackrel{¯}{\mathrm{Âì}}p{\mathrm{μ}}^{+}{\mathrm{μ}}^{−})=(1.70_{−0.56}^{+0.65}(\mathrm{stat})Â\pm 0.17(\mathrm{syst})Â\pm 0.14(\mathrm{ext}))×{10}^{−8}$ , where the last uncertainty is due to external inputs on $\mathcal{B}(B^{+}→J/\mathrm{ψ}\stackrel{¯}{\mathrm{Âì}}p)×\mathcal{B}(J/\mathrm{ψ}→{\mathrm{μ}}^{+}{\mathrm{μ}}^{−})$ . With no significant signal observed in the high $m(\stackrel{¯}{\mathrm{Âì}}p)$ region above $2.8\mathrm{GeV}/c^2$ , an upper limit is set to be ${\mathcal{B}}_{\mathrm{high}}(B^{+}→\stackrel{¯}{\mathrm{Âì}}p{\mathrm{μ}}^{+}{\mathrm{μ}}^{−})<2.8(3.7)×{10}^{−9}$ at the 90% (95%) confidence level.