Observation of B0bar --> D0 K0bar and B0bar --> D0 K*0bar decays

TL;DR

This paper reports the first observation of B0bar decays to D0 K0bar and D0 K*0bar, measuring their branching fractions with data from the Belle detector, and sets upper limits for other related decay modes.

Contribution

First observation and measurement of B0bar --> D0 K0bar and B0bar --> D0 K*0bar decay branching fractions using Belle data.

Findings

Observed B0bar --> D0 K0bar with branching fraction ~5.0 x 10^{-5}

Observed B0bar --> D0 K*0bar with branching fraction ~4.8 x 10^{-5}

Set upper limits for other decay modes

Abstract

We report on a search for B0bar --> D0 K(*)0bar decays based on 85 10^6 BBar events collected with the Belle detector at KEKB. The B0bar --> D0 K0bar and B0bar --> D0 K*0bar decays have been observed for the first time with the branching fractions Br(B0bar --> D0 K0bar) = (5.0^{+1.3}_{-1.2}+- 0.6) 10^{-5} and Br(B0bar --> D0 K*0bar) = (4.8^{+1.1}_{-1.0}+- 0.5) 10^{-5}. No significant signal has been found for the B0bar --> D*0 K(*)0bar and B0bar --> D(*)0bar K*0bar decay modes, and upper limits at 90% CL are presented.