Polarized Lepton Scattering as a Probe of Gauge Models

Abstract

Asymmetry of cross sections between high energy lepton beams of opposite helicities is shown to provide a useful probe of unified gauge models of weak and electromagnetic interac­ tions. Recently, absence of parity violation in heavy atoms 11 has cast a considerable doubt on ultimate validity of the W einberg-Salam model (W-S) / 1 and prompted many alternative models several of which are referred below. Further crucial search of neutral current phenomena, besides the well-established neutrino process, will be carried out in measurements of parity violation in lighter atoms 31 and forward-backward asymmetry in the reaction e+ e- -'>/.f.+ !J.- 41 at PEP and PETRA energies, both of which are discussed extensively in literatures. 31 ' 41 On the other hand, it was shown 51 that asymmetry of inclusive cross sections between opposite, longitudinally-polarized lepton beams ranges up to 3% for Q 2 = 100 Ge V 2 and the full strength GF of neutral current (V-A) coupling. The effect was further applied 61 to the W-S in which the asymmetry is found several times reduced due to an accidental value of the weak mixing angle Bw. The purpose of this paper is to further extend this result such that one can find expressions of the asymmetry