S-factor and Scattering Parameters from (formula presented)He + (formula presented)He (formula presented)Be + (formula presented) Data

Abstract

We use the next-to-leading-order (NLO) amplitude in an effective field theory (EFT) for (formula presented) to perform the extrapolation of higher-energy data to solar energies. At this order the EFT describes the capture process using an s-wave scattering length and effective range, the asymptotic behavior of (formula presented) and its excited state, and short-distance contributions to the E1 capture amplitude. We use a Bayesian analysis to infer the multi-dimensional posterior of these parameters from capture data below 2 MeV. The total S factor (formula presented) keV b at 68% degree of belief. We also find significant constraints on (formula presented)–(formula presented) scattering parameters.