n p ---> d gamma for big bang nucleosynthesis
Journal
Physical Review
Journal Volume
C60
Pages
065205
Date Issued
1999-07
Author(s)
Abstract
The cross section for np→dγ is calculated at energies relevant to big-bang nucleosynthesis using the recently developed effective field theory that describes the two-nucleon sector. The E1 amplitude is computed up to N3LO and depends only upon nucleon-nucleon phase shift data. In contrast, the M1 contribution is computed up to next-to-leading order, and the four-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 ∼ 1 MeV is estimated to be ≲4%.
Type
journal article