Interplay of single-particle and collective modes in the $^{12}$C(p,2p) reaction near 100 MeV

TL;DR

This study uses a three-particle scattering formalism to analyze the $^{12}$C(p,2p)$^{11}$B reaction at 98.7 MeV, revealing the importance of core excitation in reaction mechanisms and matching experimental data.

Contribution

It extends the scattering formalism to include core excitation effects, providing a more comprehensive understanding of the reaction dynamics.

Findings

Core excitation significantly contributes to the reaction cross section.

Theoretical calculations align with experimental data when including core excitation.

Reaction populates excited states not accessible via single-particle mechanisms.

Abstract

The $^{12}$C(p,2p)$^{11}$B reaction at $E_p =98.7$ MeV proton beam energy is analyzed using a rigorous three-particle scattering formalism extended to include the internal excitation of the nuclear core or residual nucleus. The excitation proceeds via the core interaction with any of the external nucleons. We assume the $^{11}$B ground and low-lying excited states [$\frac32^-$ (0.0 MeV), $\frac52^-$ (4.45 MeV), $\frac72^-$ (6.74 MeV)] and the excited states [$\frac12^-$ (2.12 MeV), $\frac32^-$ (5.02 MeV)] to be members of $K=\frac32^-$ and $K=\frac12^-$ rotational bands, respectively. The dynamical core excitation results in a significant cross section for the reaction leading to the $\frac52^-$ (4.45 MeV) excited state of $^{11}$B that cannot be populated through the single-particle excitation mechanism. The detailed agreement between the theoretical calculations and data depends on the used optical model parametrizations and the kinematical configuration of the detected nucleons.