Probing a color glass condensate in high energy heavy ion collisions

Abstract

At very high energies, the partons in the nuclear wavefunction form a color glass condensate. Since the occupation number of partons in the color glass condensate is large, classical methods can be used to compute multi-particle production in the initial instants of a high energy heavy ion collision. Non-perturbative expressions are derived relating the distributions of produced partons to those of wee partons in the wavefunctions of the colliding nuclei. The time evolution of components of the stress-energy tensor is studied and the impact parameter dependence of elliptic flow is extracted. We discuss the space-time picture that emerges and interpret the RHIC data within this framework.

Classical gluon production amplitude for nucleus-nucleus collisions: First saturation correction in the projectile

“…(1.1). This function was extensively studied numerically in [18][19][20][21][22][23][24]. Still it appears desirable to attain a better handle on the analytic form of this function.…”

“…(1.2)) does lead to the k T -factorization formula [49,50], it is not clear whether k T -factorization holds beyond the p+A approximation, again due to our lack of knowledge of c n,m for n, m ≥ 2. Moreover, numerical simulations of the classical gluon production [18][19][20][21][22][23][24] for nucleus-nucleus (A + A) collisions appear to rule out the k T -factorization ansatz, suggesting that this factorized result is only valid for p+A.…”

Time-dependent observables in heavy ion collisions. Part II. In search of pressure isotropization in the φ4 theory

“…For heavy ion collisions analyzed in the saturation framework the leading contribution to, say, the energy-momentum tensor of the produced medium is given by the classical gluon field of the MV model [9][10][11][12][13][14][15]. This is already a very difficult calculation, only possible to be fully done numerically due to the complexity of the analytic attempts [44,45] (see [46][47][48][49][50] for perturbative results valid for proton-proton and proton-nucleus collisions).…”

Classical Gluon Production Amplitude for Nucleus-Nucleus Collisions: First Saturation Correction in the Projectile

“…At the moment we do not have an analytic expression for the function f (Q . This function was extensively studied numerically in [18][19][20][21][22][23][24]. Still it appears desirable to attain a better handle on the analytic form of this function.…”

“…(2)) does lead to the k T -factorization formula [49,50], it is not clear whether k T -factorization holds beyond the p + A approximation, again due to our lack of knowledge of c n,m for n, m ≥ 2. Moreover, numerical simulations of the classical gluon production [18][19][20][21][22][23][24] for nucleus-nucleus (A + A) collisions appear to rule out the k T -factorization ansatz, suggesting that this factorized result is only valid for p + A.…”