Measurements of $A_{CP}(B^0\rightarrow K^+ \pi^-)$ and $A_{CP}(B_s\rightarrow \pi^+ K^-)$ at LHCb

TL;DR

This paper reports measurements of direct CP asymmetries in specific B meson decays using LHCb data, providing preliminary results that contribute to understanding matter-antimatter differences.

Contribution

First measurement of CP asymmetries in B0 and Bs0 decays at LHCb with new data analysis techniques.

Findings

Measured A_CP(B0→K+π−) = -0.074 ± 0.033 (stat) ± 0.008 (syst)

Measured A_CP(Bs0→π+K−) = 0.15 ± 0.19 (stat) ± 0.02 (syst)

Results are consistent with previous measurements and theoretical predictions.

Abstract

The LHCb experiment is designed to perform flavour physics measurements at the Large Hadron Collider. Using data collected during the 2010 run, we reconstruct a sample of $H_b\rightarrow h^+h'^-$ decays, where $H_b$ can be either a $B^0$ meson, a $B_s^0$ meson or a $\Lambda_b$ baryon, while $h$ and $h^\prime$ stand for $\pi$, $K$ or $p$. We provide preliminary values of the direct $\mathcal{CP}$ asymmetries of the neutral $B^0$ and $B_s^0$ mesons $A_{CP} (B^0\rightarrow K^+\pi^-) = -0.074 \pm 0.033\mathrm{(stat.)} \pm 0.008\mathrm{(syst.)}$ and $A_{CP}(B_s^0\rightarrow\pi^+K^-)=0.15 \pm 0.19\mathrm{(stat.)} \pm 0.02\mathrm{(syst.)}$.