Observation of the decay $B^0 \to \eta' K^*(892)^0$

TL;DR

This paper reports the first observation of the decay $B^0 o ta' K^*(892)^0$ with a measured branching fraction of approximately 2.6 x 10^{-6} and investigates its CP violation, based on a large data sample collected by the Belle detector.

Contribution

First observation of the decay $B^0 o ta' K^*(892)^0$ with measurement of its branching fraction and CP asymmetry.

Findings

Decay observed with 5.0 sigma significance.

Branching fraction measured as (2.6 ± 0.7 (stat) ± 0.2 (syst)) x 10^{-6}.

CP asymmetry measured as -0.22 ± 0.29 (stat) ± 0.07 (syst).

Abstract

We report a search for charmless hadronic decays of neutral $B$ mesons to $\eta' K^{*}(892)^{0}$. The results are based on a 711fb$^{-1}$ data sample that contains $772\times 10^6 B\overline{B}$ pairs, collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric energy $e^+e^-$ collider. We observe the decay for the first time with a significance of 5.0 standard deviations and obtain its branching fraction ${\cal B}[B^0\to\eta' K^{*}(892)^{0}]=[2.6\pm0.7{\rm (stat)}\pm0.2{\rm (syst)}]\times 10^{-6}$. We also measure the $CP$ violating asymmetry as ${\cal A}_{CP}[B^0\to\eta' K^{*}(892)^{0}]=-0.22\pm0.29{\rm (stat)}\pm0.07{\rm syst}$.