Measurement of the angle ϕ_3 with Dalitz analysis of three-body D^0 decay from B\to D^0 K process

Abstract

A new method to measure the angle $ϕ_3$ of the CKM unitarity triangle using a Dalitz analysis of the three-body decay of the $D^0$ meson from the $B\to D^0 K$ process has been introduced recently. The method employs the interference between $D^0$ and $\bar{D^0}$ to extract both the weak and strong phases. We present a study of statistical and systematic errors of this method using Monte Carlo simulation. A fit of the $D^0$ Dalitz distribution has been performed based on a 140 fb$^{-1}$ sample collected by the Belle detector. We observe the indication of a CP asymmetry with the significance of 2.4 standard deviations. The 90% confidence interval obtained for the $ϕ_3$ value is $61^{\circ}<ϕ_3<142^{\circ}$.