Dilepton production in heavy-ion collisions

Conference · Fri Dec 31 04:00:00 EST 1993

OSTI ID:57050

Ko, Che Ming ^[1]

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1. Texas A&M Univ., College Station, TX (United States)

According to the transport model for heavy-ion collisions at the Bevalac/SIS energies of around 1 GeV/nucleon, a nuclear matter with a density of 2-3 times the normal nuclear matter density can be created. This dense matter is also highly excited, with a delta to nucleon ratio reaching about 30%. Decays of these deltas give rise to an appreciable number of pions in the matter. Rho mesons can then be formed from pion-pion interactions. Heavy-ion collisions thus offer the possibility to study both the properties of dense matter and the in-medium properties of hadrons. There are already some indications that medium effects play an important role in understanding the experimental data. For example, the observation of an enhanced yield of pions with low transverse kinetic energies in heavy-ion experiments has led to the suggestion that this may be due to the softening of the pion dispersion relation in the dense matter formed in the collision. Also, deltas through their interactions with other hadrons have been shown to be largely responsible for the production of kaons, antikaons, and antiprotons from heavy-ion collisions at energies that are below their production threshold in the nucleon-nucleon interaction in free space. Futhermore, it has been demonstrated in the relativistic transport model that the reduction of kaon, antikaon, and antiproton masses due to the attractive scalar field in the dense matter can account for the observed enhancement of their yields as a result of the reduced production threshold. Because of the relatively weak interactions with other particles, dileptons created from a dense matter, unlike hadrons mentioned in the above, do not suffer final-state interactions and are thus expected to carry more direct information about the properties of dense matter and the in-medium properties of hadrons.

• Research Organization: Lawrence Berkeley Lab., CA (United States)
• OSTI ID: 57050
• Report Number(s): LBL--35984; CONF-9310315--; ON: DE95000804; CNN: Grant PHY-9212209
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DELTA BARYONS
ELECTRONS
GEV RANGE
HEAVY ION REACTIONS
MULTIPLE PRODUCTION
NUCLEI