Nd→H3γ with effective field theory

The cross section of neutron-deuteron radiative capture nd→H3γ is calculated at energies relevant to big-bang nucleosynthesis (20⩽E⩽200keV) with pionless effective field theory. At these energies, magnetic transition M1 gives the dominant contribution. The M1 amplitude is calculated up to next-to-next-to leading order (N2LO) with insertion of three-body force. Results are in good agreement within few percent theoretical uncertainty in comparison with available calculated data below E=200keV.