np -> d gamma for big-bang nucleosynthesis - art. no. 065205

The cross section for np-->d gamma is calculated at energies relevant to bi g-bang nucleosynthesis using the recently developed effective field theory that describes the two-nucleon sector. The E1 amplitude is computed up to ( NLO)-L-3 and depends only upon nucleon-nucleon phase shift data. In contras t, the M1 contribution is computed up to next-to-leading order, and the fou r-nucleon-one-magnetic-photon counterterm that enters is determined by the cross section for cold neutron capture. The uncertainty in the calculation for nucleon energies up to E similar to 1 MeV is estimated to be less than or similar to 4%. [S0556-2813(99)02612-6].