# Measurement of branching fraction and direct $CP$ asymmetry in charmless $B^+ \to K^+K^- \pi^+$ decays at Belle

## TL;DR

This paper measures the branching fraction and direct CP asymmetry in the charmless decay of B+ mesons to K+K−π+ using Belle data, revealing an excess in the low invariant mass region and significant CP violation.

## Contribution

First measurement of branching fraction and CP asymmetry in B+ → K+K−π+ decays at Belle, with detailed analysis of the invariant mass distribution and CP violation evidence.

## Key findings

- Branching fraction: (5.38 ± 0.40 ± 0.35)×10⁻⁶
- Direct CP asymmetry: -0.170 ± 0.073 ± 0.017
- Evidence of large CP asymmetry in low K+K− mass region

## Abstract

We report a study of the charmless hadronic decay of the charged $B$ meson to the three-body final state $K^+ K^- \pi^+$. The results are based on a data sample that contains $772\times10^6$ $B \bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+ e^-$ collider. The measured inclusive branching fraction and the direct $CP$ asymmetry are $(5.38\pm0.40\pm0.35)\times 10^{-6}$ and $-0.170\pm0.073\pm0.017$, respectively, where the first uncertainties are statistical and the second are systematic. The $K^{+}K^{-}$ invariant mass distribution of the signal candidates shows an excess in the region below $1.5$ GeV/$c^2$, which is consistent with the previous studies from BaBar and LHCb. In addition, strong evidence of a large direct $CP$ asymmetry is found in the $K^{+}K^{-}$ low-invariant-mass region.