Parity-Violating Asymmetry in Electron- Polarized Deuteron Scattering

Abstract

5in the electron (or muon) scattering angles from 0 to 35 for a given energy of 1 Ge V in the Weinberg-Salam model. It has been of particular interest to determine the relevant structure of electron-( muon-) quark sector weak neutral-current couplings. ' ) The determination, however, has been rather difficult to study experimentally, because electron (or muon) is coupled with quarks by the electromagnetic and weak interaction, so that one must look for effects that are characteristic of the weak interaction, and for a parity-violation. Parity-violation in longitudinally polarized electrons from unpolarized deuterons has been observed at SLAC. 2 ) That in atomic physics has also been studied, while the experimental situations for bismuth are still confusing. 3 ) So, we need some other experiments to determine the weak neutral-current couplings of electron­ (muon-) quark sector and to discuss the reliability of some gauge models on weak and electro­ magnetic interactions. The neutral current effects in the lepton elastic scattering by polarized proton target have been investigated by Bilen'kii et al. ' ) They have defined the longitudinal asymmetry and have estimated at very high energy of a few handred GeV. They also have defined the transverse asymmetry and have only referred to be small which is the proton part of our parity-violating asymmetry and is suggested to be important in this letter. Because of the high energy of incident leptons, the cross sections discussed by them are quite small and they are far from performing the experiment. Then, when we consider similar reactions, the in­ termediate energy less than a few Ge V is one of the essential parts on feasibility. In this letter, we discuss the parity-violating asymmetry in the process e+ d i ..... e' + d or (p, n) and give the numerical estimates using the standard Weinberg-Salam model 4 ) at the incident electron (or muon) energy of 1 GeV. The relevant Feynman diagrams and the kine­ matical configuration are shown in Figs. 1 and 2. The calculation has been made in the impulse approximation and we have neglected the nuclear corrections such as the final state interaction between proton and neutron which are expected to be smaller contributions to our results. In the impulse approximation, it is well known that the matrix elements of the electro­ magnetic and the weak hadronic currents are given in terms of the Sachs form factors 5 ) when