Evidence from Identified Particles for Active Quark and Gluon Degrees of Freedom

Abstract

Measurements of intermediate pT (1.5 < pT < 5.0 GeV/c) identified particle distributions in heavy ion collisions at SPS and RHIC energies display striking dependencies on the number of constituent quarks in the corresponding hadron. One finds that elliptic flow at intermediate pT follows a constituent quark scaling law as predicted by models of hadron formation through coalescence. In addition, baryon production is also found to increase with event multiplicity much faster than meson production. The rate of increase is similar for all baryons, and seemingly independent of mass. This indicates that the number of constituent quarks determines the multiplicity dependence of identified hadron production at intermediate pT. We review these measurements and interpret the experimental findings.

arXiv comment8 pages, 5 figures, proceedings for SQM2006 conference in Los Angeles

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• Coalescence Models For Hadron Formation From Quark Gluon Plasma
• Heavy baryon/meson ratios in relativistic heavy ion collisions
• Consequences of a Lambda_c/D enhancement effect on the non-photonic electron nuclear modification factor in central heavy ion collisions at RHIC energy
• The QCD confinement transition: hadron formation
• Phase-Space Coalescence for heavy and light quarks at RHIC