Department of Physics and Astronomy

Nuclear and Particle Physics Seminar

Monday, October 4

12:30pm-1:30pm

Stevenson Center, Room 6333

Walter Greiner
Goethe-Universität, Frankfurt

Clusters of Matter and Antimatter

We study the possibility of producing a new kind of nuclear system which in addition to ordinary nucleons contains a few antibaryons. The properties of such systems are described within the relativistic mean-field model by employing G-parity transformed interactions for antibaryons. Calculations are first done for infinite systems and then for finite nuclei from 4He to 208Pb. It is demonstrated that the presence of a real antibaryon leads to a strong rearrangement of the target nucleus resulting in a significant increase of its binding energy and local compression. Noticeable effects remain even after antibaryon coupling constants are reduced by a factor of 3-4 compared to G-parity motivated values. We have performed detailed calculations of the antibaryon annihilation rates in the nuclear environment by applying the kinetic approach. It is shown that due to significant reduction of reaction Q-values, the in-medium annihilation rates should be strongly suppressed leading to relatively long-lived antibaryon-nucleus systems. Multi-nucleon annihilation channels are analyzed too. We have also estimated formation probabilities of antiproton+A bound systems in antiproton-A reactions and have found that their observation is feasible at the future GSI antibaryon facility. Several observable signatures are proposed. The possibility of producing multi-quark-antiquark clusters is discussed.

Clusters of baryons and antibaryons lead to strong, cold compression of nuclear matter, thus furnishing the possibility to study compressed baryon matter at low temperature. This must be seen in contrast to the hot, strong compression caused in nuclear shock waves in high energy heavy ion collisions.