Measurement of the CKM angle gamma from a combination of B->Dh analyses

TL;DR

This paper combines three measurements from LHCb to determine the CKM angle gamma using B->Dh decays, providing precise confidence intervals and a best-fit value, accounting for D0-D0bar mixing effects.

Contribution

It presents a combined analysis of multiple B->Dh decay measurements to improve the precision of the CKM angle gamma determination.

Findings

Best-fit gamma from B->DK decays is 72.0° with 68% CL interval [56.4°,86.7°]

Best-fit gamma from B->Dpi decays is 18.9° with 68% CL interval [7.4°,99.2°]

Combined B->DK and B->Dpi results give gamma = 72.6° with 68% CL interval [55.4°,82.3°]

Abstract

A combination of three LHCb measurements of the CKM angle gamma is presented. The decays B->DK and B->Dpi are used, where D denotes an admixture of D0 and D0-bar mesons, decaying into K+K-, pi+pi-, K+-pi-+, K+-pi-+pi+-pi-+, KSpi+pi-, or KSK+K- final states. All measurements use a dataset corresponding to 1.0 fb-1 of integrated luminosity. Combining results from B->DK decays alone a best-fit value of gamma = 72.0 deg is found, and confidence intervals are set gamma in [56.4,86.7] deg at 68% CL, gamma in [42.6,99.6] deg at 95% CL. The best-fit value of gamma found from a combination of results from B->Dpi decays alone, is gamma = 18.9 deg, and the confidence intervals gamma in [7.4,99.2] deg or [167.9,176.4] deg at 68% CL, are set, without constraint at 95% CL. The combination of results from B->DK and B->Dpi decays gives a best-fit value of gamma = 72.6 deg and the confidence intervals gamma in [55.4,82.3] deg at 68% CL, gamma in [40.2,92.7] deg at 95% CL are set. All values are expressed modulo 180 deg, and are obtained taking into account the effect of D0-D0bar mixing.