Proposal for testing lepton universality in Upsilon decays at a B-factory running at ${\rm Y}(3S)$

Abstract

We present a proposal for detecting new physics at a B-factory running at the ${\rm Y}(3S)$ resonance by testing lepton universality to the few percent level in the leptonic decays of the ${\rm Y}(1S)$ and ${\rm Y}(2S)$ resonances tagged by the dipion in the chain decay: ${\rm Y}(3S)\to p{i}^{+}{\pi }^{-}{\rm Y}(1S,2S)$; ${\rm Y}(1S,2S)\to {\ell }^{+}{\ell }^{-}$, $\ell =e,\mu ,\tau$.

Comments: 10 pages, 2 figures, Contributed paper to BNM2006 Workshop, September 13-14, 2006, KEK