On the possibility of Bose condensation of pions in ultrarelativistic collisions of nuclei

Journal Article · Wed Jun 01 04:00:00 EDT 1994 · Journal of Experimental and Theoretical Physics

OSTI ID:28458

Voskresenskii, D N ^[1]

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1. Moscow Engineering Physics Institute (Russian Federation)

The properties of the pion subsystem that arises in the process of ultrarelativistic collisions of nuclei are studied. For this a model of the expanding pion fireball is used in which, right up to the time the fireball breaks up, it is assumed that local thermal quasiequilibrium is present but chemical equilibrium is absent. The properties of a pion system with a Bose condensate are studied in the approximation of an ideal relativistic pion gas. The value of the critical Bose-condensation temperature T{sub c} of the pions is estimated, and it is shown that this value apparently exceeds the characteristic value that determines the slope of the experimental pion spectra in ultrarelativistic collisions of nuclei. The yield of pions is found, and is shown to be enhanced in the region of small momenta. It is shown that if there is a condensate at the initial time it is also preserved during subsequent uniform isentropic expansion. It is demonstrated that the photon acquires mass as a consequence of the interaction of the {pi}{sup +} and {pi}{sup {minus}} condensates with the electromagnetic vacuum. It is shown that the {rho}{sup 0} meson acquires a large additional mass as a consequence of the analogous effect. Arguments are given in favor of a substantial decrease in the yield of dileptons in the presence of a Bose condensate of pions. The properties of a system with a pion condensate at finite temperatures are studied. The specifics of Bose condensation of pions in the {sigma}-model are considered. It is shown that the nucleon mass decreases as the density of the pion condensate increases, and can even vanish for p > P{sub c} {approximately} p{sub nucl}, where p{sub nucl} is the density of the atomic nucleus. This decrease of the nucleon mass can manifest itself in an enhanced yield of N{bar N} pairs from the region of the pion fireball. 21 refs.

• OSTI ID: 28458
• Journal Information: Journal of Experimental and Theoretical Physics, Journal Name: Journal of Experimental and Theoretical Physics Journal Issue: 6 Vol. 78; ISSN 1063-7761; ISSN JXTPAS
• Country of Publication: United States
• Language: English

Related Subjects

66 PHYSICS
DEEP INELASTIC HEAVY ION REACTIONS
NUCLEAR FIREBALL MODEL
NUCLEI
PION CONDENSATION