Higher twist effects in parity-violating electron deuteron scattering

Parity-Violating Deep Inelastic Scattering (PVDIS) of polarized electrons from deuterium can in principle probe higher twist quark-quark correlations beyond the parton model. As first observed by Bjorken and Wolfenstein, the dominant contribution to the electron polarization asymmetry, proportional to the axial vector electron coupling, receives corrections at twist-four from the matrix element of a single four-quark operator. In particular, because the contribution of the relevant twist four operator satisfies the Callan-Gross relation, the ratio of parity-violating longitudinal and transverse cross sections, R-gamma Z, is identical to that for purely electromagnetic scattering, R-gamma Z up to perturbative and power suppressed contributions. This result simplifies the interpretation of the asymmetry for experiments planned at the Thomas Jefferson National Accelerator Facility (JLab). The results of MIT Bag Model calculations are used to give benchmark estimates of the relevant twist four operator contribution to the leading term in the asymmetry as a function of Bjorken x and Q(2). These are compared with corrections to the asymmetry due to violation of charge symmetry in the parton distribution functions.