Measurement of the branching fraction for γ (1S) → τ+τ-

Abstract We have studied the leptonic decay of the γ (1 S ) resonance into tau pairs using the CLEO II detector. A clean sample of tau pair events is identified via events containing two charged particles where exactly one of the particles is an identified electron. We find B ( γ (1 S ) → τ + τ − ) = (2.61±0.12 −0.13 +0.09 )%. The result is consistent with expectations from lepton universality