Possibility of cold nuclear compression in antiproton-nucleus collisions

TL;DR

This study investigates the potential for antiprotons to induce local nuclear compression in oxygen-16 nuclei during collisions, using a microscopic transport model to estimate the likelihood and characteristics of such events.

Contribution

It introduces a two-stage scheme to evaluate nuclear compression in antiproton-nucleus collisions, combining dynamical modeling with realistic antibaryon coupling constants.

Findings

Antiprotons with momentum below the Fermi level can create compressed nuclear zones.

The probability of compression-induced annihilation events is approximately 10^{-5} at certain energies.

Maximum nuclear density can reach about twice the saturation density during compression.

Abstract

We study the dynamical response of the oxygen-16 nucleus to an incident antiproton using the Giessen Boltzmann-Uehling-Uhlenbeck microscopic transport model with relativistic mean fields. A special emphasis is put on the possibility of a dynamical compression of the nucleus induced by the moving antiproton. Realistic antibaryon coupling constants to the mean meson fields are chosen in accordance with empirical data. Our calculations show that an antiproton embedded in the nuclear interior with momentum less than the nucleon Fermi momentum may create a locally compressed zone in the nucleus with a maximum density of about twice the nuclear saturation density. To evaluate the probability of the nuclear compression in high-energy antiproton-nucleus collisions, we adopt a two-stage scheme. This scheme takes into account the antiproton deceleration due to the cascade of antiproton-nucleon rescatterings inside the nucleus (first stage) as well as the nuclear compression by the slow antiproton before its annihilation (second stage). With our standard model parameters, the fraction of antiproton annihilation events in the compressed zone is about $10^{-5}$ for $\bar p ^{16}$O collisions at $p_{\rm lab}=3-10$ GeV/c. Finally, possible experimental triggers aimed at selecting such events are discussed.