Studies of Hyperons and Antihyperons in Nuclei

TL;DR

This paper explores hyperon and antihyperon production in nuclei using antiproton beams, modeling hypernuclear excited states and analyzing hadron-antihadron momentum correlations to understand their nuclear potentials.

Contribution

It introduces a model for excited double hypernuclei formation and compares predictions with experimental pion spectra, also analyzing momentum correlations to probe hyperon potentials.

Findings

Excited hypernuclear states dominate over ground states in the model.

Different initial nuclei lead to different double hypernuclei production.

Momentum correlations can reveal potential differences between hyperons and antihyperons.

Abstract

Stored antiproton beams at the international FAIR facility will provide unique opportunities to study hyperons as well as antihyperons in nuclear systems. Precise $\gamma$-spectroscopy of multi-strange hypernuclei will serve as a laboratory for the hyperon-hyperon interaction. Exclusive hadron-antihadron pair production close to threshold can measure the potential of a antihadron relative to that of the coincident hadrons. In the present work we explore the production of excited states in double hypernuclei following the micro-canonical break-up of an initially excited double hypernucleus which is created by the absorption and conversion of a stopped $\Xi^{-}$ hyperon. Generally the formation of excited hypernuclear states relative to ground states dominates in this model. For different initial target nuclei which absorb the $\Xi^-$, different double hypernuclei nuclei dominate. We also compare the model predictions with the correlated pion spectra measured by the E906 collaboration. In antiproton nucleus reactions the event-by-event transverse momentum correlations of hadron-antihadron pairs produced close to threshold contain information on the difference between the nuclear potential of the hadron and the associated antihadron. For produced D-meson pairs at 6.7\gevc1 the sensitivity of the transverse momenta correlation will probably be to small to deduce differences between the potentials for D$^+$ and D$^-$ mesons. However, for {\PgX\PagX} pairs produced at 2.9\gevc1 the asymmetry is sufficiently sensitive to predicted differences between the {\PgX} and {\PagX} potentials even if the momentum and density dependence of the the potential are taken into account.