Antibaryon interactions with the nuclear medium

TL;DR

This study investigates antibaryon interactions with nuclei using relativistic mean-field models, focusing on antiproton binding and absorption, and compares phenomenological and potential-based approaches to understand their in-medium behavior.

Contribution

It provides a detailed analysis of antibaryon-nucleus interactions, incorporating dynamic annihilation effects and comparing phenomenological and potential-based models for antiproton binding energies.

Findings

Antiproton widths are significantly reduced in the nuclear medium.

Binding energies are about 10% smaller with the Paris potential.

Antiproton widths are approximately 20% larger in the potential-based approach.

Abstract

This contribution deals with our recent study of antibaryon interactions with the nuclear medium within the relativistic mean-field approach using antibaryon coupling constants consistent with available experimental data. We performed calculations of $\bar{B}$ ($\bar{B}=\bar{p}, \bar{\Lambda}, \bar{\Sigma}, \bar{\Xi}$) bound states in selected nuclei. Due to the lack of information on the in-medium antihyperon annihilation near threshold only the $\bar{p}$ absorption was considered. It was described by the imaginary part of a phenomenological optical potential fitted to $\bar{p}$-atom data. The annihilation was treated dynamically, taking into account explicitly the reduced phase space for annihilation products in the nuclear medium, as well as the compressed nuclear density due to the antiproton. The energy available for the annihilation products was evaluated self-consistently, considering additional energy shift due to particle momenta in the ${\bar p}$-nucleus system. Corresponding $\bar{p}$ widths were significantly reduced, however, they still remain sizable. Next, the $\bar{p}$-nucleus interaction was constructed using the latest version of the Paris $\bar{N}N$ potential. Related scattering amplitudes were used to define the complex $\bar{p}$ optical potential in the nuclear medium. The resulting $\bar{p}$ $1s$ binding energies are about 10% smaller and widths about 20% larger than those obtained with the phenomenological approach.