Evidence of strong dynamic core excitation in $^{19}$C resonant break-up

TL;DR

This paper analyzes the resonant break-up of $^{19}$C on protons, demonstrating that including core excitation effects is crucial for accurately modeling the process and matching experimental data.

Contribution

It introduces a valence-core model for $^{19}$C that incorporates core excitations, improving the understanding of its break-up behavior.

Findings

Core excitation effects are essential for accurate cross section predictions.

Inert core models significantly underestimate experimental data.

The model supports the $5/2^{+}$ state assignment for the observed resonance.

Abstract

The resonant break-up of $^{19}$C on protons measured at RIKEN [Phys. Lett. B 660, 320 (2008)] is analyzed in terms of a valence-core model for $^{19}$C including possible core excitations. The analysis of the angular distribution of a prominent peak appearing in the relative-energy spectrum could be well described with this model and is consistent with the previous assignment of $5/2^{+}$ for this state. Inclusion of core-excitation effects are found to be essential to give the correct magnitude of the cross section for this state. By contrast, the calculation assuming an inert $^{18}$C core is found to largely underestimate the data.