First measurement of the decay-time-integrated $C\!P$ asymmetry in $B_s^0 \to D_s^- \pi^+$ decays

TL;DR

This paper reports the first measurement of the decay-time-integrated CP asymmetry in B_s^0 to D_s^- pi^+ decays using LHCb data, finding results consistent with the Standard Model and constraining new physics.

Contribution

It presents the first measurement of the CP asymmetry in B_s^0 decays, using proton-proton collision data at 13 TeV from LHCb, with results that align with Standard Model predictions.

Findings

Measured CP asymmetry: (-1.4 ± 5.9 (stat) ± 1.1 (syst)) × 10^{-3}

Results are consistent with Standard Model expectations

Provides constraints on new physics in b-hadron decays

Abstract

A measurement of the flavour-untagged decay-time-integrated ${C\!P}$ asymmetry in the flavour-specific decay ${B_s^0 \to D_s^-\pi^+}$, ${\langle A^s_{\rm untagged}\rangle}$, is performed using proton-proton collision data collected by the LHCb experiment between 2016 and 2018 at a center-of-mass energy of ${13\,{\rm TeV}}$, corresponding to a total integrated luminosity of ${5.4\,{\rm fb}^{-1}}$. The ${C\!P}$ asymmetry is measured in two $D_s^-$ meson decay modes, ${D_s^- \to K^-K^+\pi^-}$ and ${D_s^- \to \pi^-\pi^+\pi^-}$. The combined result, $\langle A^s_{\rm untagged}\rangle = ( -1.4 \pm 5.9\,\rm{(stat)} \pm 1.1\,\rm{(syst)}) \times 10^{-3}$, is consistent with the Standard Model expectation and provides a direct constraint on new physics in tree-level $b$-hadron decays.