Measurement of $\gamma$ from $B \rightarrow DK$ decays at LHCb

TL;DR

This paper presents the first measurements of the CKM angle gamma using B to DK decays at LHCb, employing multiple methods to achieve the most precise direct measurement from a single experiment.

Contribution

It introduces new measurements of gamma using B to DK decays with three methods and a novel time-dependent approach with B_s to D_s K decays, improving precision.

Findings

Gamma measured as (57 ± 16)° from D^0 Dalitz analysis.

Combined gamma value is 67.2° with 68% CL interval [55.1°, 79.1°].

First use of time-dependent approach with B_s decays for gamma measurement.

Abstract

We report results from the first measurements of the CKM angle $\gamma$ using $B\rightarrow DK$ decays with the LHCb experiment. Three well established methods are used to extract the CP observables. The updated measurement of $\gamma$ in the three-body $D^0$ Dalitz space results in $\gamma = (57\pm 16)^\circ$. When combining the observables from all \bdk studies, the best fit value for $\gamma \in [0,180]^\circ$ is $\gamma = 67.2^\circ$ with $\gamma \in [55.1,79.1]^\circ$ at 68%CL and $\gamma \in [43.9, 89.5]^\circ$ at 95%CL. This represents the most precise $\gamma$ values directly measured by a single experiment. Furthermore, a new time-dependent approach using $B_s \rightarrow D_s K$ decays is used for the first time to measure CP observables and future prospects for $\gamma$ at LHCb are given.