Study of nuclear correlation effects via 12C(p,n)12N(g.s.,1+) at 296 MeV

TL;DR

This study measures polarization observables in the 12C(p,n)12N reaction at 296 MeV to investigate nuclear correlation effects, revealing discrepancies with theoretical models partly explained by pionic correlations.

Contribution

It introduces detailed polarization measurements and compares them with advanced models, highlighting the role of pionic correlations in nuclear structure.

Findings

Cross section under-predicted by models at high momentum transfer

Non-locality of nuclear mean field partially explains discrepancies

Pionic correlations contribute to observed cross section enhancements

Abstract

We report measurements of the cross section and a complete set of polarization observables for the Gamow--Teller ${}^{12}{\rm C}(\vec{p},\vec{n}){}^{12}{\rm N}({\rm g.s.},1^+)$ reaction at a bombarding energy of 296 MeV. The data are compared with distorted wave impulse approximation calculations employing transition form factors normalized to reproduce the observed beta-decay $ft$ value. The cross section is significantly under-predicted by the calculations at momentum transfers $q \gtrsim $ 0.5 ${\rm fm^{-1}}$. The discrepancy is partly resolved by considering the non-locality of the nuclear mean field. However, the calculations still under-predict the cross section at large momentum transfers of $q$ $\simeq$ 1.6 ${\rm fm^{-1}}$. We also performed calculations employing random phase approximation response functions and found that the observed enhancement can be attributed in part to pionic correlations in nuclei.