Search for $B \to \pi \ell^+\ell^-$ Decays at Belle

TL;DR

This paper reports a search for rare B meson decays to a pion and a lepton pair, setting upper limits on their branching fractions due to no significant signal being observed.

Contribution

First search for B-> pi l+ l- decays at Belle, establishing upper limits on their branching fractions with a large data sample.

Findings

No significant signal observed.

Upper limit on branching fraction: < 6.2 x 10^-8.

Data sample of 657 million BBbar pairs.

Abstract

We present a search for the B-> pi e^+ e^- and B-> pi \mu^+ \mu^- decays, with a data sample of 657 million BBbar pairs collected with the Belle detector at the KEKB $e^+e^-$ collider. Signal events are reconstructed from a charged or a neutral pion candidate and a pair of oppositely charged electrons or muons. No significant signal is observed and we set the upper limit on the isospin-averaged branching fraction BF(B -> \pi \ell^+\ell^-) < 6.2x10^-8 at the 90% confidence level.