Measurement of CP violation in the decay $B^{+} \rightarrow K^{+} \pi^{0}$

TL;DR

This paper reports the most precise measurement to date of direct CP violation in the decay $B^{+} ightarrow K^{+} \pi^{0}$, providing crucial data for understanding anomalies in B meson decay asymmetries.

Contribution

It presents the first high-precision measurement of CP asymmetry in $B^{+} ightarrow K^{+} \pi^{0}$ decay, surpassing previous experimental accuracy.

Findings

Measured CP asymmetry as 0.025 ± 0.015 ± 0.006 ± 0.003

Confirms previous measurements, reinforcing the $K ext{-} ext{pi}$ puzzle

Enhances understanding of CP violation in B meson decays

Abstract

A measurement of direct CP violation in the decay $B^{+} \rightarrow K^{+} \pi^{0}$ is reported using a data sample corresponding to an integrated luminosity of 5.4 $\textrm{fb}^{-1}$, collected with the LHCb experiment at a center-of-mass energy of $\sqrt{s}=13$ TeV. The CP asymmetry is measured to be $0.025 \pm 0.015 \pm 0.006 \pm 0.003$, where the uncertainties are statistical, systematic, and due to an external input, respectively. This is the most precise measurement of the CP asymmetry in the decay $B^{+} \rightarrow K^{+} \pi^{0}$ and exceeds the precision on the current world average. This direct CP asymmetry is a key input to studies of a long-standing anomaly in $B$ meson decays, known as the $K\pi$-puzzle. The asymmetry is consistent with the previous measurements of this quantity, confirming and significantly enhancing the observed anomalous difference between the direct CP asymmetries of the $B^{0} \rightarrow K^{+} \pi^{-}$ and $B^{+} \rightarrow K^{+} \pi^{0}$ decays.