Coupled-channels treatment of Be7(p,γ)B8 in effective field theory

Abstract

The $E1$ and $M1$ contributions to $^{7}\mathrm{Be}(p,\ensuremath{\gamma})^{8}\mathrm{B}$ at low energies are calculated in halo effective field theory. The excited $^{7}\mathrm{Be}^{★}$ 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 $^{8}\mathrm{B}$ is included. We compare our results with previous halo effective field theory calculations that also included the $^{7}\mathrm{Be}^{★}$ 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.