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Radiative neutron capture on a proton at BBN energies

S. Ando·R. H. Cyburt·S. W. Hong·C. H. Hyun
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Abstract

The total cross section for radiative neutron capture on a proton, $np \to d γ$, is evaluated at big bang nucleosynthesis (BBN) energies. The electromagnetic transition amplitudes are calculated up to next-to leading order within the framework of pionless effective field theory with dibaryon fields. We also calculate the $dγ\to np$ cross section and the photon analyzing power for the $d\vecγ\to np$ process from the amplitudes. The values of low energy constants that appear in the amplitudes are estimated by a Markov Chain Monte Carlo analysis using the relevant low energy experimental data. Our result agrees well with those of other theoretical calculations except for the $np\to dγ$ cross section at some energies estimated by an R-matrix analysis. We also study the uncertainties in our estimation of the $np\to dγ$ cross section at relevant BBN energies and find that the estimated cross section is reliable to within $\sim$1% error.

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S. Ando, R. H. Cyburt, S. W. Hong, C. H. Hyun. 2006-07-07. Radiative neutron capture on a proton at BBN energies. https://doi.org/10.1103/physrevc.74.025809

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