Range corrections in Proton Halo Nuclei

TL;DR

This paper investigates finite-range effects in proton halo nuclei using effective field theory, calculating charge radii and S-factors, and compares results with experimental data, revealing the fine-tuning challenges in proton halo formation.

Contribution

It introduces a systematic low-energy expansion for proton halo nuclei that includes finite-range corrections and applies it to real data, highlighting the fine-tuning issues.

Findings

Finite-range corrections affect charge radius and S-factor calculations.

The low-energy theory provides a quantifiable model error for data fitting.

Proton halos require two fine tunings, making their existence less likely.

Abstract

We analyze the effects of finite-range corrections in halo effective field theory for S-wave proton halo nuclei. We calculate the charge radius to next-to-leading order and the astrophysical S-factor for low-energy proton capture to fifth order in the low-energy expansion. As an application, we confront our results with experimental data for the S-factor for proton capture on Oxygen-16 into the excited $1/2^+$ state of Fluorine-17. Our low-energy theory is characterized by a systematic low-energy expansion, which can be used to quantify an energy-dependent model error to be utilized in data fitting. Finally, we show that the existence of proton halos is suppressed by the need for two fine tunings in the underlying theory.