Inclusive $J/\psi$ and $\Upsilon$ emissions from single-parton fragmentation in hybrid high-energy and collinear factorization

TL;DR

This paper investigates the production of heavy quarkonia like $J/c$ and $ ext{Upsilon}$ in high-energy collisions, combining collinear and high-energy QCD factorization to explore production mechanisms at large transverse momenta.

Contribution

It introduces a hybrid high-energy and collinear factorization framework for quarkonium production, incorporating perturbative fragmentation functions and BFKL resummation techniques.

Findings

Proposes a new channel to study quarkonium production mechanisms.

Combines collinear and high-energy resummation approaches.

Provides theoretical predictions for heavy quarkonium plus jet production.

Abstract

We present a novel study on the inclusive production of a heavy quarkonium ($J/\psi$ or $\Upsilon$), in association with a light-flavored jet, as a test field of the high-energy QCD dynamics. The large transverse momenta at which the two final-state objects are detected permits us to perform an analysis in the spirit of the variable-flavor number scheme (VFNS), in which the cross section for the hadroproduction of a light parton is convoluted with a perturbative fragmentation function that describes the transition from a light quark to a heavy hadron. The quarkonium collinear fragmentation function is built as a product between a short-distance coefficient function, which encodes the resummation of DGLAP type logarithms, and a non-perturbative long-distance matrix element (LDME), calculated in the non-relativistic QCD (NRQCD) framework. Our theoretical setup is the hybrid high-energy and collinear factorization, where the standard collinear approach is supplemented by the resummation of leading and next-to-leading energy-type logarithms \emph{\`a la} BFKL. We propose this reaction as a suitable channel to probe the production mechanisms of quarkonia at high energies and large transverse momenta and to possibly unveil the transition region from the heavy-quark pair production mechanism to the single-parton fragmentation one.