# Bayesian analysis of capture reactions $^3\mathrm{He}(\alpha,\gamma)^7\mathrm{Be}$ and $^3\mathrm{H}(\alpha,\gamma)^7\mathrm{Li}$

## TL;DR

This paper uses Bayesian methods to analyze key nuclear capture reactions, comparing effective field theory models to determine the dominant contributions and providing insights into reaction cross sections relevant for astrophysics.

## Contribution

It introduces a Bayesian framework for model comparison of two EFT power countings in nuclear capture reactions, highlighting the role of two-body currents at different orders.

## Key findings

- Two-body currents are favored at leading order for $^3$He($ o$)$^7$Be with elastic scattering data.
- Both models are equally favored without elastic scattering constraints.
- The model with leading order two-body currents is favored for $^3$H($ o$)$^7$Li regardless of elastic data.

## Abstract

Bayesian analysis of the radiative capture reactions $^3\mathrm{He}(\alpha,\gamma)^7\mathrm{Be}$ and $^3\mathrm{H}(\alpha,\gamma)^7\mathrm{Li}$ are performed to draw inferences about the cross sections at threshold. We do a model comparison of two competing effective field theory power countings for the capture reactions. The two power countings differ in the contribution of two-body electromagnetic currents. In one power counting, two-body currents contribute at leading order, and in the other they contribute at higher orders. The former is favored for $^3\mathrm{He}(\alpha,\gamma)^7\mathrm{Be}$ if elastic scattering data in the incoming channel is considered in the analysis. Without constraints from elastic scattering data, both the power countings are equally favored. For $^3\mathrm{H}(\alpha,\gamma)^7\mathrm{Li}$, the first power counting with two-body current contributions at leading order is favored with or without constraints from elastic scattering data.