Measurement of interference between W and Z exchange in electron-neutrino electron scattering.

A measurement of the reaction {nu}{sub {ital e}}+{ital e}{sup {minus}}{r arrow}{nu}{sub {ital e}}+{ital e}{sup {minus}} was performed using a beam-stop source of {nu}{sub {ital e}}. Based upon 234{plus minus}35 events, we obtain a cross section of {sigma}({nu}{sub {ital ee}})=(9.9{plus minus}1.5(stat){plus minus}1.0(syst)){times}10{sup {minus}42} cm{sup 2} {times}({ital E}{sub {nu}} (GeV)). This reaction is mediated by the exchange of {ital W} and {ital Z} bosons and is thus sensitive to the interference between them. This interference is measured to be {minus}1.07{plus minus}0.17(stat){plus minus}0.11(syst), consistent with the destructive interference ({minus}1.08) predicted by the standard model.