Coupled-channels treatment of ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ in effective field theory

Abstract

The E1 and M1 contributions to ${}^7\mathrm{Be}(p,\gamma {)}^8\mathrm{B}$ at low energies are calculated in halo effective field theory. The excited ${}^7{\mathrm{Be}}^{\star }$ core is included as an explicit degree of freedom in a coupled-channels calculation. The E1 transition is calculated up to next-to-next-to-leading order. The leading contribution from M1 transition that gives significant contribution in a narrow energy region around the $1^{+}$ resonance state of ${}^8$B is included. We compare our results with previous halo effective field theory calculations that also included the ${}^7{\mathrm{Be}}^{\star }$ as an explicit degree of freedom. We disagree with these previous calculations in both the formal expressions and also in the analysis. Bayesian inference of the data gives $S_{17}(0)=21.0(7)$ eV b when combined with the expected theory error.

Comments: 21 pages, 11 figures, 4 tables, updated manuscript, results unchanged