QCD transverse-momentum resummation in gluon fusion processes - High Energy Physics - PhenomenologyReport as inadecuate

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Abstract: We consider the production of a generic system of non-strongly interactingparticles with a high total invariant mass M in hadron collisions. We examinethe transverse-momentum q T distribution of the system in the small-q Tregion q T << M, and we present a study of the perturbative QCD contributionsthat are enhanced by powers of large logarithmic terms of the type lnM^2-q T^2. These terms can be resummed to all orders in QCD perturbationtheory. The partonic production mechanism of the final-state system can becontrolled by quark-antiquark qqbar annihilation and-or by gluon fusion. Theresummation formalism for the qqbar annihilation subprocess is wellestablished, and it is usually extrapolated to the gluon fusion subprocess. Wepoint out that this naive extrapolation is not correct, and we present theall-order resummation formula for the q T distribution in gluon fusionprocesses. The gluon fusion resummation formula has a richer structure than theresummation formula in qqbar annihilation. The additional structure originatesfrom collinear correlations that are a specific feature of the evolution of thecolliding hadrons into gluon partonic states. In the q T cross section at smallvalues of q T, these gluon collinear correlations produce coherent spincorrelations between the helicity states of the initial-state gluons anddefinite azimuthal-angle correlations between the final-state particles of theobserved high-mass system.

Author: S. Catani, M. Grazzini

Source: https://arxiv.org/

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