Observation of B+ -> rho+ rho0

TL;DR

This paper reports the first observation of the B+ -> rho+ rho0 decay, measuring its branching fraction and polarization, providing new insights into charmless B meson decays at the Upsilon(4S) resonance.

Contribution

It presents the first observation and measurement of the B+ -> rho+ rho0 decay, including branching fraction and polarization, using data from the Belle detector.

Findings

Branching fraction Br(B+ -> rho+ rho0) = (31.7 +- 7.1 (stat.) +3.8-6.7 (sys.)) x 10^{-6}

Longitudinal polarization fraction = (94.8 +- 10.6 (stat.) +- 2.1 (sys.))%

First observation of this charmless vector-vector decay mode.

Abstract

We report the first observation of the charmless vector-vector decay process B+ ->rho+ rho0. The measurement uses a 78 fb^{-1} data sample collected with the Belle detector at the KEKB asymmetric e+e- collider operating at the Upsilon(4S) resonance. We obtain a branching fraction of Br(B+ ->rho+ rho0)=(31.7+-7.1(stat.)+3.8-6.7(sys.))*10^{-6}. An analysis of the rho helicity-angle distributions gives a longitudinal polarization of Gamma_{L}/Gamma=(94.8+-10.6(stat.)+-2.1(sys.))%.