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arXiv · 0704.3537

Dijet correlations at RHIC, leading-order $k_t$-factorization approach versus next-to-leading order collinear approach

Antoni Szczurek·Anna Rybarska·Gabriela Slipek
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Abstract

We compare results of $k_t$-factorization approach and 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 UGDF/UPDF used. For collinear 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 $2 \to 2$ contributions associated with soft radiations summed up in the $k_t$-factorization approach dominate at $ϕ\sim π$ and at equal moduli of jet transverse momenta. The collinear NLO $2 \to 3$ 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.

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Antoni Szczurek, Anna Rybarska, Gabriela Slipek. 2007-04-26. Dijet correlations at RHIC, leading-order $k_t$-factorization approach versus next-to-leading order collinear approach. https://doi.org/10.1103/physrevd.76.034001

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