Search for $C\!P$ violation in $\Lambda^0_b \to p K^-$ and $\Lambda^0_b \to p \pi^-$ decays

TL;DR

This paper reports the most precise measurements to date of $C ext{P}$ violation asymmetries in specific $ ext{Lambda}_b^0$ decays, using LHCb data from proton-proton collisions.

Contribution

It provides the first high-precision measurements of $C ext{P}$ violation asymmetries in $ ext{Lambda}_b^0$ decays to $pK^-$ and $p ext{pi}^-$, improving the sensitivity over previous studies.

Findings

Measured $A_{CP}^{pK^-} = -0.020 \

Measured $A_{CP}^{p ext{pi}^-} = -0.035 \

Difference $A_{CP}^{pK^-} - A_{CP}^{p ext{pi}^-} = 0.014 \

Abstract

A search for $C\!P$ violation in $\Lambda^0_b \to p K^-$ and $\Lambda^0_b \to p \pi^-$ decays is presented using a sample of $pp$ collisions collected with the LHCb detector and corresponding to an integrated luminosity of 3.0 fb$^{-1}$. The $C\!P$-violating asymmetries are measured to be $A_{\mathrm{CP}}^{pK^-} = -0.020 \pm 0.013\pm 0.019$ and $A_{\mathrm{CP}}^{p\pi^-} = -0.035 \pm 0.017 \pm 0.020 $, and their difference $A_{\mathrm{CP}}^{pK^-}-A_{\mathrm{CP}}^{p\pi^-} = 0.014 \pm 0.022 \pm 0.010$, where the first uncertainties are statistical and the second systematic. These are the most precise measurements of such asymmetries to date.