Parity-violating photon circular polarization in p plus d → 3He + γ with pion-less effective field theory

The nonleptonic weak interaction in the few-nucleon system at very low energies is studied with the calculation of the photon circular polarization in the pd -> (3)Hey reaction (P-gamma(pd)). For very low energies, one may treat the pion as heavy and integrate it out from the QCD symmetry-based model-independent effective field theory, leaving only short-range strong interactions which are introduced in term of pionless effective field theory formulation. We investigate a complete set of the parity-violating electromagnetic transitions in the pd 3Hey process. In this paper the interferences of strong, electromagnetic, Coulomb, and parity-violating weak interactions are presented with the calculation of a full set of appropriate diagrams at the leading order. We have obtained energy-dependent P-gamma(Pd) results as a function of the laboratory energy values 0.5 <= E-Lab <= 3 MeV in terms of the low-energy coupling constants. The contributions of the initial S- and P-wave proton-deuteron systems have been considered to make the final He-3 ground state in this energy region.