A Search for the Rare Leptonic Decays B+ -> mu+ nu and B+ -> e+ nu

TL;DR

This paper reports a search for rare leptonic decays of B+ mesons into mu+ nu and e+ nu, setting upper limits on their branching fractions due to no significant signals observed.

Contribution

First search for B+ -> mu+ nu and B+ -> e+ nu decays using Belle data, establishing upper limits on their branching ratios.

Findings

No significant evidence for the decays was found.

Upper limits on branching fractions were set at 1.7 x 10^{-6} and 9.8 x 10^{-7}.

Results constrain new physics models affecting leptonic B decays.

Abstract

We present a search for the decays B+ -> mu+ nu_mu and B+ -> e+ nu_e in a 253 fb-1 data sample collected at the \Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy B factory. We find no significant evidence for a signal and set 90% confidence level upper limits of B(B+ -> mu+ nu_mu) < 1.7 x 10^{-6} and B(B+ -> e+ nu_e) < 9.8 x 10^{-7}.