Measurement of the CKM angle $\gamma$ using the $B^{\pm}\rightarrow D^{*} h^{\pm}$ channels

TL;DR

This paper measures the CKM angle gamma using B+/- to D* h+/- decays, analyzing CP violation without relying on amplitude models, based on LHCb data at multiple energies, and reports a gamma value around 69 degrees.

Contribution

It provides a model-independent measurement of the CKM angle gamma using D* decay phase space analysis from LHCb data, including new hadronic parameters.

Findings

Measured gamma as (69 +13/-14) degrees.

Reported hadronic parameters for B decays.

Analysis is independent of amplitude models.

Abstract

A measurement of the $CP$-violating observables from $B^{\pm}\rightarrow D^* K^{\pm}$ and $B^{\pm}\rightarrow D^* \pi^{\pm}$ decays is presented, where $D^* (D) $ is an admixture of $D^{*0}$ and $\bar{D}^{*0}$ ($D^0$ and $\bar{D}^0$) states and is reconstructed through the decay chains $ D^* \rightarrow D\pi^0/\gamma$ and $D \to K_S^0 \pi^+\pi^-/K_S^0 K^+K^-$. The measurement is performed by analysing the signal yield variation across the $D$ decay phase space and is independent of any amplitude model. The data sample used was collected by the LHCb experiment in proton-proton collisions and corresponds to a total integrated luminosity of 9 fb$^{-1}$ at centre-of-mass energies of 7, 8 and 13 TeV. The CKM angle $\gamma$ is determined to be $(69^{+13}_{-14})^{\circ}$ using the measured $CP$-violating observables. The hadronic parameters $r^{D^* K^{\pm}}_B, r^{D^* \pi^{\pm}}_B, \delta^{D^* K^{\pm}}_B, \delta^{D^* \pi^{\pm}}_B$, which are the ratios and strong phase differences between favoured and suppressed $B^{\pm}$ decays, are also reported.