Constraints on R-parity violating couplings from lepton universality

We analyze the one loop corrections to leptonic W and Z decays in an R-parity violating extension to the minimal supersymmetric standard model. We find that lepton universality violation in the Z line-shape variables alone would strengthen the bounds on the magnitudes of the {lambda}{sup '} couplings, but a global fit on all data leaves the bounds virtually unchanged at |{lambda}{sub 33k}{sup '}|{<=}0.42 and |{lambda}{sub 23k}{sup '}|{<=}0.50 at the 2{sigma} level. Bounds from W decays are less stringent: |{lambda}{sub 33k}{sup '}|{<=}2.4 at 2{sigma}, as a consequence of the weaker Fermilab experimental bounds on lepton universality violation in W decays. We also point out the potential of constraining R-parity violating couplings from the measurement of the {upsilon} invisible width. (c) 2000 The American Physical Society.