Dijet correlations at BNL RHIC: Leading-order k(t)-factorization approach versus next-to-leading order collinear approach

作者：Szczurek A^*; Rybarska A; Slipek G

来源：Physical Review D - Particles, Fields, Gravitation and Cosmology, 2007, 76(3): 034001.

DOI：10.1103/PhysRevD.76.034001

We compare results of the k(t)-factorization approach and the next-to-leading-order collinear-factorization approach for dijet correlations in proton-proton collisions at RHIC energies. We discuss correlations in azimuthal angle as well as correlations in two-dimensional space of transverse momenta of two jets. Some k(t)-factorization subprocesses are included for the first time in the literature. Different unintegrated gluon/parton distributions are used in the k(t)-factorization approach. The results depend on unintegrated gluon distribution functions (UGDF)/unintegrated parton distribution UPDF) used. For the collinear next-to-leading order (NLO) case, the situation depends significantly on whether we consider correlations of any two jets or correlations of leading jets only. In the first case, the 2 -> 2 contributions associated with soft radiations summed up in the k(t)-factorization approach dominate at phi similar to pi and at equal moduli of jet transverse momenta. The collinear NLO 2 -> 3 contributions dominate over k(t)-factorization cross section at small relative azimuthal angles as well as for asymmetric transverse-momentum configurations. In the second case, the NLO contributions vanish at small relative azimuthal angles and/or large jet transverse-momentum disbalance due to simple kinematical constraints. There are no such limitations for the k(t)-factorization approach. All this makes the two approaches rather complementary. The role of several cuts is discussed and quantified.

• 出版日期2007-8