In this manuscript, we analyze the contribution of fragmentation mechanisms to the inclusive hadroproduction of heavy quarkonium pairs, taking into account both single- and double-hadron (dihadron) fragmentation channels. To estimate the contribution of the latter mechanism, we construct a microscopic perturbative model of the dihadron fragmentation function, which is valid in the limit of large invariant masses of the heavy quarkonium pair. Using the Color Glass Condensate framework to evaluate the $Q\bar{Q}$ production amplitude, we find that in LHC kinematics, the single fragmentation of heavy quarks into quarkonium is only a minor correction, whereas dihadron fragmentation can provide a sizable contribution, on par with the contributions of single- and double-parton scattering.
In this manuscript, we present the results of our studies on the exclusive photoproduction of quarkonium-photon pairs with large invariant mass. In our analysis, we focus on the production of the ηcγ and χcJγ pairs in high energy kinematics. We use the Color Glass Condensate (CGC) framework for analysis and demonstrate that at leading order in αs the cross-sections of these processes are determined by the forward dipole scattering amplitude. The kinematic distributions of the produced particles allow us to study the dipole amplitude in detail, making this process a very clean probe for studies of saturation physics. Using phenomenological parametrizations of the dipole amplitudes, we estimate numerically the differential production cross-sections for ηcγ and χcγ in the kinematics of ultraperipheral collisions at the LHC and the future Electron-Ion Collider (EIC). Furthermore, we assess the role of this process as a possible background to the exclusive photoproduction of C-even quarkonia, which is frequently considered as a tool for odderon searches.
M. Siddikov, I. Zemlyakov, M. Roa· Particles· 0 citations
