Measurement of $C\!P$ asymmetries in two-body $B_{(s)}^{0}$-meson decays to charged pions and kaons

TL;DR

This paper reports measurements of time-dependent and time-integrated $C ext{P}$ asymmetries in specific $B$-meson decays using LHCb data, providing evidence of $C ext{P}$ violation in $B_s^0 o K^+K^-$ for the first time.

Contribution

First measurement of $C ext{P}$ asymmetries in $B_{(s)}^0$ decays to charged pions and kaons using 3.0 fb$^{-1}$ of LHCb data, including the first evidence of $C ext{P}$ violation in $B_s^0 o K^+K^-$.

Findings

Measured $C ext{P}$ asymmetries with statistical and systematic uncertainties.

Evidence of $C ext{P}$ violation in $B_s^0 o K^+K^-$ decay.

Quantified asymmetries in multiple decay channels.

Abstract

The time-dependent $C\!P$ asymmetries in $B^0\to\pi^+\pi^-$ and $B_s^0\to K^+\!K^-$ decays are measured using a data sample of $pp$ collisions corresponding to an integrated luminosity of 3.0 fb$^{-1}$, collected with the LHCb detector at centre-of-mass energies of 7 and 8 TeV. The same data sample is used to measure the time-integrated $C\!P$ asymmetries in $B^0\to K^+\pi^-$ and $B_s^0\to\pi^+ K^-$ decays. The results are $C_{\pi^+\pi^-} = -0.34 \pm 0.06 \pm 0.01$, $S_{\pi^+\pi^-} = -0.63 \pm 0.05 \pm 0.01$, $C_{K^+\!K^-} = 0.20 \pm 0.06 \pm 0.02$, $S_{K^+\!K^-} = 0.18 \pm 0.06 \pm 0.02$, $C_{K^+\!K^-}^{\Delta\Gamma} = -0.79 \pm 0.07 \pm 0.10$, $A_{C\!P}^{B^0} = -0.084 \pm 0.004 \pm 0.003$, and $A_{C\!P}^{B_s^0} = 0.213 \pm 0.015 \pm 0.007$, where the first uncertainties are statistical and the second systematic. Evidence for $C\!P$ violation is found in the $B_s^0\to K^+\!K^-$ decay for the first time.