PARTICLE PRODUCTION AT RHIC FROM QUARK RECOMBINATION

Abstract

Particle production at RHIC is discussed within the framework of quark recombination model. After a short introduction on the anomalies discovered at RHIC, we will first present the basic physics ideas common for all the quark recombination models and different implementations in different research groups. Then the main focus turns to the approach of Oregon group. Feynman and Field's independent fragmentation process is re-interpreted in the quark recombination model. In this approach, hard partons with high virtuality evolves into a shower of semihard partons by radiating gluons which can convert into quark-antiquark pairs. Then different fragmentation functions can be rewritten in terms of only a few shower parton distributions within the recombination model. By fitting the data on the fragmentation functions, the shower parton distributions can be determined and then can be used in other processes together with the assumed exponential distributed soft parton distributions. Applications to the particle production at RHIC for both Au + Au and d + Au collisions in mid-rapidity are discussed. In particular, the suppression for meson production in central Au + Au collisions and Cronin effect in d + Au collisions are naturally explained within the recombination models. Finally, strange particle production is briefly discussed.