Weak Neutral Currents in Electron and Muon Scattering*

Contributions to inelastic scattering arising from the interference of a weak neutral current with the electromagnetic current are calculated using the Weinberg model and the quark parton model. These interferences produce nonvanishing (dd daf) , -(L) (do d$(R)), (dostL) do-(R)) which give rise to sizeable affects when compared to the purely electromagnetic scattering. (Submitted to Phys. Rev. Comments) * Supported in part by the U.S. Atomic Energy Commission. Preliminary measurements of inelastic neutrino and anti-neutrino reactions at CERN’ and NAL2 indicate the possibility of neutral neutrino currents which are in turn coupled to hadrons. These measurements of v + N v -Ix and F+N V + x are in rough agreement with the predictions of the Weinberg SU(2) X U(1) model gauge theory of weak interactions coupled with the model of nucleons composed of fractionally-charged quarks. 3 In particular the fact that the observed neutrino and anti-neutrino cross sections are not equal requires an interference between vector and axial vector currents and necessarily excludes the possibility that the effect is electromagnetic in origin (such as the charge radius of the neutrino). It is the purpose of this modest note to point out that in the same model, quite sizeable weak neutral current effects are predicted in charged lepton deep inelastic scattering l* + N L* + x. 495 The estimates reported in this paper can be regarded as indicating typical magnitudes for neutral current effects, with the specific numbers dependent on the Weinberg model as well as on the parton model. Because the discovery of weak neutral currents coupled to leptons is fundamental to the connection of weak interactions with electromagnetism and because rough theoretical estimates indicate that the measurements are not beyond present experimental possibilities, moderately difficult experimental searches for such weak effects should be considered at present accelerators. We consider in this paper three experimental measurements of weak neutral current contributions to deep inelastic lepton scattering unpolarized lepton vs. antilepton scattering (typically a SLAC experiment): R(j-j+) &(I-+N+-+x) -da(j++N -,J?++x) t do(e+ N -e+ x) + da(j+ + N j+ + x) (1)