Speaker
Description
The formalism of gauge-invariant EFT for Multi-Regge processes in QCD is used to compute impact-factors relevant for processes of production of heavy quarkonia within Non-Relativistic QCD Factorisation formalism and High-Energy Factorisation at one-loop accuracy. The examples of $\gamma+R\to c\bar{c}\left[{}^1S_0^{[8]}\right]$ and $g+R\to c\bar{c}\left[{}^1S_0^{[1]}\right]$ impact factors will be considered, with $R$ being the Reggeized gluon and the final-state $c\bar{c}$ pair is projected on a specified state ${}^{2S+1}L_J^{[1,8]}$. In the process of computation, the one-loop integrals with rapidity divergences and massive internal lines have been encountered and procedure for their computation has been developed. The results for the impact-factor in the EFT has been cross-checked against the Regge limit of an exact one-loop QCD amplitude $\gamma+g\to c\bar{c}\left[ {}^1S_0^{[8]} \right] + g$, which is another highly nontrivial check of the EFT formalism. The results will be applied to computation of $p_T$-integrated cross sections of inclusive $J/\psi$ photoproduction and $\eta_c$ hadroproduction in the matching approach of Refs.[1,2].
[1] https://arxiv.org/abs/2306.02425
[2] https://arxiv.org/abs/2112.06789 [JHEP 05 (2022) 083]
