Search for B→πℓ+ℓ- decays at Belle

Abstract

We present a search for the decays B+→π+ℓ+ℓ- and B0→π0ℓ+ℓ-, where ℓ+ℓ- is either a μ+μ- or e+e- pair, with a data sample of 657×106 BB̄ 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 an upper limit on the isospin-averaged branching fraction B(B→πℓ+ℓ-)<6.2×10-8 at the 90% confidence level. © 2008 The American Physical Society.