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The neutral-current effects in the exclusive lepton pair production with a circularly polarized photon beam on a proton target are discussed. We derive the parity-violating asymmetry for the lepton produced by rightand left-handed photons. It is expressed in terms of the well-known electromagnetic and weak form factors of the nucleons. Numerical calculations are given in the standard Weinberg-Salam model. We show the asymmetry as a function of the lepton energy in some kinematical configurations. The neutral-current effects are of order 10-7 "'-'10-' in the lepton production angle range from 1o to 10° for the incident photon energy of 20 GeV.

The weak neutral·current effects in electron-polarized deuteron scattering are investigated in the Weinberg-Salam, SU(3)x UO) and SU(2hxSU(2)RX UO) gauge models. We derive the parity-violating asymmetry for the scattered electron. It is expressed in terms of wellknown electromagnetic and weak form factors of the nucleon. The asymmetries are expected to be of the order of 1O~6 and 1O~5 at the incident electron energy of 0.5 GeV and 2 GeV for each gauge model. The experiment at 0.5 Ge V gives the strong constraints on these gauge models and at 2 Ge V may be useful to discriminate them.

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