Search

In the collinear twist-three approach, we calculate for the first time the gluon contribution to double-(longitudinal-transverse) spin asymmetry ALT for open charm production in proton-proton collisions measurable at RHIC. Utilizing the Ward-Takahashi identity for the nonpole part of the hard scattering amplitude, we derive a factorized, gauge invariant formula for the asymmetry. The result may be combined with the previous studies of single-spin asymmetry in the same channel and allows for a systematic analysis of three-gluon correlations inside a transversely polarized nucleón. [ABSTRACT FROM AUTHOR]

Motivated by the problem of thermalization in heavy ion collisions, we present numerical simulations of the nonequilibrium evolution of the 0(N) model in 1 + 2 dimensions with longitudinal expansion and in the presence of a background field. We work in the next-to-leading-order approximation of the 1/N expansion and consider both the strong and weak coupling cases. Special emphasis is put on the difference between the two-particle irreducible formalism and the classical statistical approach. In the two-particle irreducible case at strong coupling, we find some evidence of the Bose-Einstein (exponential) distribution in the expanding system. [ABSTRACT FROM AUTHOR]

Recently, X. Chen et al. proposed a new approach to the gauge invariant decomposition of the nucleon spin into the helicity and orbital angular momentum of quarks and gluons. The key ingredient in their construction is the separation of the gauge field into physical and "pure gauge" parts. We suggest a simple separation scheme and show that the resulting gluon helicity coincides with the first moment of the conventional polarized gluon distribution measurable in high energy experiments. [ABSTRACT FROM AUTHOR]

We confront the theoretical result of single spin asymmetry AN in forward pA collisions p↑A→hX including the gluon saturation effect with the recent preliminary experimental data from the PHENIX and STAR Collaborations at the Relativistic Heavy Ion Collider. While we find overall reasonable agreement with the STAR data, our results indicate that the strong nuclear suppression of the asymmetry AN∼A-1/3 observed by the PHENIX Collaboration cannot be explained within the present understanding of this problem. [ABSTRACT FROM AUTHOR]

I review high energy, small angle scattering in Regge theory, QCD and strongly coupled N = 4 SYM theory with emphasis on the behavior of scattering amplitudes near the unitarity limit.