Eur. Phys. J. C (2009) 59: 891-898
https://doi.org/10.1140/epjc/s10052-008-0854-5

Regular Article - Theoretical Physics

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

Department of Physics, University of Illinois, Chicago, IL, 60607, USA

^* e-mail: gnayak@uic.edu

Received: 5 November 2008
Published online: 9 January 2009

Abstract

In this paper we implement the Schwinger–Keldysh closed-time path integral formalism in non-equilibrium QCD in accordance to the definition of the Collins–Soper fragmentation function. We consider a high-p _T parton in QCD medium at initial time τ ₀ with an arbitrary non-equilibrium (non-isotropic) distribution function 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.