Fragmentation function in non-equilibrium QCD using closed-time path integral formalism

摘要

In this paper we implement the Schwinger_Keldysh closed-time path integral formalism in non-equilib_rium QCD in accordance to the definition of the Collins_Soper fragmentation function. We consider a high-PT parton in QCD medium at initial time τ0 with an arbitrary non-equilibrium (non-isotropic) distribution function f (( )) fragmenting to a hadron. We formulate the parton-to-hadron fragmentation function in non-equilibrium QCD in the light-cone quantization formalism. It may be possible to include final-state interactions with the medium via a modification of the Wilson lines in this definition of the non-equilibrium fragmentation function. This may be relevant to the study of hadron production from a quark_gluon plasma at RHIC and LHC.