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arXiv · 1811.07611

$S$-factor and scattering parameters from ${}^3$He + ${}^4$He $\rightarrow {}^7$Be + $\gamma$ data

Xilin Zhang·Kenneth M. Nollett·Daniel R. Phillips
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Abstract

We use the next-to-leading-order (NLO) amplitude in an effective field theory (EFT) for ${}^3$He + ${}^4$He $\rightarrow {}^7$Be + $\gamma$ 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 $^7$Be 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 $S(0)= 0.578^{+0.015}_{-0.016}$ keV b at 68% degree of belief. We also find significant constraints on $^3$He-$^4$He scattering parameters.

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Xilin Zhang, Kenneth M. Nollett, Daniel R. Phillips. 2018-11-19. $S$-factor and scattering parameters from ${}^3$He + ${}^4$He $\rightarrow {}^7$Be + $\gamma$ data. https://arxiv.org/abs/1811.07611

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