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The universal freeze-out criterion at SPS and RHIC

Boris Tomasik·Urs Achim Wiedemann
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Abstract

We formulate a freeze-out criterion for ultra-relativistic heavy ion collisions in terms of the pion escape probability from the collision region. We find that the increase in pion phase-space density from SPS to RHIC reported at this conference has a small influence on particle freeze-out because of the small pi-pi cross-section. Our treatment takes into account dynamical expansion, chemical composition and momentum of the escaping particle for particle freeze-out. It supports a freeze-out at rather low temperature - below 100 MeV - and earlier decoupling of high p_t particles.

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Boris Tomasik, Urs Achim Wiedemann. 2002-08-29. The universal freeze-out criterion at SPS and RHIC. https://doi.org/10.1016/s0375-9474(02)01552-x

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