A model-independent measurement of the CKM angle γ in the decays B±→ [K+K−π+π−]Dh± and B±→ [π+π−π+π−]Dh± (h = K, π)

Abstract

A model-independent determination of the CKM angle γ is presented, using the B± → [K+K−π+π−]Dh± and B± → [π+π−π+π−]Dh± decays, with h = K, π. This measurement is the first phase-space binned study of these decay modes, and uses a sample of proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9 fb−1. The phase-space bins are optimised for sensitivity to γ, and in each bin external inputs from the BESIII experiment are used to constrain the charm strong-phase parameters. The result of this binned analysis is γ=53.9−8.9+9.5°$$ \gamma ={\left(53.{9}{-8.9}^{+9.5}\right)}^{{}^{\circ}} $$, where the uncertainty includes both statistical and systematic contributions. Furthermore, when combining with existing phase-space integrated measurements of the same decay modes, a value of γ=52.6−6.4+8.5°$$ \gamma ={\left(52.{6}{-6.4}^{+8.5}\right)}^{{}^{\circ}} $$ is obtained, which is one of the most precise determinations of γ to date.