A study of $C\!P$ violation in the decays $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^{\pm}$ ($h = K, \pi$) and $B^\pm\to[\pi^+\pi^-\pi^+\pi^-]_D h^{\pm}$

TL;DR

This paper reports the first measurement of $C ext{P}$ violation in specific $B^ ext{±}$ decays involving four-body charm final states, using LHCb data to explore local asymmetries and determine $ ext{C} ext{P}$-violating observables.

Contribution

It introduces the first analysis of $C ext{P}$ violation in these decay modes, utilizing phase-space binning and external charm decay parameters for sensitivity to the angle $oldsymbol{ extgamma}$.

Findings

First observation of $C ext{P}$ violation in these decay modes.

Measurement of phase-space integrated $C ext{P}$ asymmetries.

Determination of observables sensitive to the angle $oldsymbol{ extgamma}$.

Abstract

The first study of $C\!P$ violation in the decay mode $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^\pm$, with $h=K,\pi$, is presented, exploiting a data sample of proton-proton collisions collected by the LHCb experiment that corresponds to an integrated luminosity of $9$ fb$^{-1}$. The analysis is performed in bins of phase space, which are optimised for sensitivity to local $C\!P$ asymmetries. $C\!P$-violating observables that are sensitive to the angle $\gamma$ of the Unitarity Triangle are determined. The analysis requires external information on charm-decay parameters, which are currently taken from an amplitude analysis of LHCb data, but can be updated in the future when direct measurements become available. Measurements are also performed of phase-space integrated observables for $B^\pm\to[K^+K^-\pi^+\pi^-]_D h^\pm$ and $B^\pm\to[\pi^+\pi^-\pi^+\pi^-]_D h^\pm$ decays.