Proposal for Testing Lepton Universality in Upsilon Decays at a B Factory Running at Υ(3S)

Abstract

A proposal is presented for detecting new physics at a B factory running at the Υ(3 S ) resonance by testing lepton universality to the few percent level in the leptonic decays of the Υ(1 S ) and Υ(2 S ) resonances tagged by the dipion in the chain decay: Υ(3 S )→π + π - Υ(1 S ,2 S ); Υ(1 S ,2 S )→l + l - , l= e ,µ,τ.