Correlations at intermediatep_T

Abstract

Abstract. Correlations among hadrons in jets produced in heavy-ion collisions are discussed in the framework of the recombination model. The basic correlation at the parton level is among the shower partons arising from kinematical constraint. The resultant correlation between hadrons at intermediate pT is amazingly rich in characteristics. IntroductionThe study of the correlations at intermediate p T in heavy-ion collisions at high energy is important for the understanding of the interaction between a hard parton and the hot dense medium that it traverses. By intermediate p T we mean the region that stands between the soft region (p T < 2 GeV/c) where the recombination of thermal partons is most important and the hard region (p T > 9 GeV/c) where the fragmentation of partons is dominant. Note that this classification of regions is determined by the modes of hadronization, which we shall review briefly, rather than by the nature of scattering, soft or hard. In the intermediate p T region the recombination of the thermal and shower partons is more important than any other component of hadronization and clearly conveys the medium effect on hard partons. And it is in that region where the recent analysis of the data from RHIC reveals a wealth of information on jet structure. We shall examine the properties of correlation in the framework of parton recombination, which is the only viable hadronization scheme that can account for the species dependence of the particles produced. Our emphasis will be on near-side correlation, which depends mainly on the correlation among shower partons in a jet. The away-side correlation involves other issues besides hadronization and will be the subject of a future investigation.