Measurement of phi_3 in B->D(*)K Decays at Belle

TL;DR

This paper measures the unitarity triangle angle phi_3 using Dalitz plot analysis of D0 decays from B->DK processes, providing a key parameter for understanding CP violation in the quark sector.

Contribution

It introduces a Dalitz plot analysis method to extract phi_3 from B->D(*)K decays, utilizing interference effects and applying it to Belle data for the first time.

Findings

Measured phi_3 as 81 degrees with uncertainties

Established a 95% confidence interval for phi_3

Demonstrated the effectiveness of Dalitz plot analysis in this context

Abstract

We present a measurement of the unitarity triangle angle phi_3 using a Dalitz plot analysis of the three-body decay of the D0 meson from the B+- -> D(*)K+- process. The method employs the interference between D0 and D0bar to extract both the weak and strong phases. We apply this method to the 140 fb-1 of data collected by Belle experiment. The analysis uses B+- -> DK+- and B+- -> D*K+- with D*->Dpi0 modes, where the neutral D meson decays into K_s pi+ pi-. From a combined maximum likelihood fit of B+- -> DK+- and B+- -> D*K+- modes, we obtain phi_3=81^{\circ}+-19^{\circ}+-13(syst)+-11^{\circ}(model). The 95% confidence interval is 35^{\circ}<phi_3<127^{\circ}.