Measurement of phi_3 with Dalitz Plot Analysis of B->D(*)K Decay

TL;DR

This paper measures the unitarity triangle angle phi_3 using Dalitz plot analysis of B->D(*)K decays, employing interference effects to extract weak and strong phases from experimental data.

Contribution

It introduces a Dalitz plot analysis method for phi_3 measurement in B decays, combining data from B->DK and B->D*K modes to improve phase determination.

Findings

Measured phi_3 as 77 degrees with uncertainties

Obtained a two-standard-deviation interval of 26 to 126 degrees

Analyzed 146 B->DK and 39 B->D*K candidates

Abstract

We present a measurement of the unitarity triangle angle phi_3 using a Dalitz plot analysis of the three-body decay of the neutral D 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 a 140 fb^{-1} data sample collected by the Belle experiment. The analysis uses the modes B->DK and B->D*K, D*->D pi0, where the neutral D meson decays into K_Spi+pi-. We obtain 146 signal candidates for B->DK and 39 candidates for B->D*K. From a combined maximum likelihood fit to the B->DK and B->D*K modes, we obtain phi_3=77^{\circ}^{+17}_{-19}(stat)+-13^{\circ}(syst)}+-11^{\circ}(model). The corresponding two standard deviation interval is 26^{\circ}<phi_3<126^{\circ}.