Alpha-Alpha scattering, chiral symmetry and 8Be lifetime

TL;DR

This paper investigates alpha-alpha scattering using a chiral two-pion exchange potential, establishing a correlation between the Q-factor and lifetime of 8Be, and compares theoretical predictions with experimental data.

Contribution

It introduces a model-independent correlation between the Q-factor and 8Be lifetime based on a chiral potential approach, aligning theoretical results with experimental observations.

Findings

Predicted 8Be decay width Gamma ≈ 4.4 eV, close to experimental 5.57 eV.

Chiral two-pion exchange potential is attractive and singular, requiring renormalization.

Phase shift analysis up to 15 MeV can be explained by peripheral nuclear contributions.

Abstract

Alpha-alpha scattering is discussed in terms of a chiral two pion exchange potential which turns out to be attractive and singular at the origin, hence demanding renormalization. When 8Be is treated as a resonance state a model independent correlation between the Q-factor and lifetime 1/Gamma for the decay into two alpha particles arises. For a wide range of parameters compatible with potential model analyses of low energy pi-alpha scattering it is found Gamma = 4.4(4)eV} in fairly good agreement with the experimental value Gamma = 5.57 (25) eV. The remaining discrepancy as well as the phase shift up to ELAB=15MeV could be accommodated by the leading nuclear peripheral contributions due to the 3H+p and 3He+n continuum.