Constraints on the CKM angle gamma in B^0 --> barD^0 (D^0) K^*0 from a Dalitz analysis of D^0 --> K_S pi^+ pi^-

TL;DR

This paper measures the CKM angle gamma using a Dalitz analysis of D0 decays from B0 meson processes, providing constraints on gamma and the amplitude ratio r_S with data from the BaBar experiment.

Contribution

It presents a novel Dalitz analysis approach to constrain gamma in B0 decays, incorporating a large dataset and measuring gamma as a function of r_S.

Findings

Gamma estimated as (162 +- 56) degrees or (342 +- 56) degrees.

r_S constrained to be less than 0.55 at 95% probability.

Provides the first direct measurement of gamma using this decay mode.

Abstract

We present constraints on the angle gamma of the Unitarity Triangle with a Dalitz analysis of neutral D decays to K_Spi^+pi^- from the processes B^0 -> barD^0 K^*0 (barB^0 -> D^0 barK^*0) and B0 -> D0 K*0 (barB^0 -> barD^0 barK^*0) with K^*0 -> K^+pi^- (barK^*0 -> K^-pi^+). Using a sample of 371 10^6 BBbar pairs collected with the Babar detector at PEP-II, we measure the angle gamma as a function of r_S, the magnitude of the average ratio between b -> u and b -> c amplitudes. Combining this result with the available information on r_S, we obtain gamma = (162 +- 56) degrees or (342 +- 56) degrees and r_S<0.55 at 95% probability.