$J/\psi$ production in proton-proton collisions at Spin Physics Detector energies of the JINR Nuclotron-based Ion Collider fAcility

TL;DR

This study uses simulations with different gluon TMD models to analyze $J/eta$ production in proton-proton collisions at energies relevant for the SPD at NICA, highlighting the sensitivity of quarkonium production to gluon dynamics.

Contribution

First detailed assessment of $J/eta$ production sensitivity to gluon TMDs near threshold energies, guiding upcoming experimental measurements at SPD/NICA.

Findings

Differential cross sections are stable under scale variation.

Distinct $p_T$ hardening patterns linked to gluon $k_T$ broadening.

Color-octet mechanisms dominate $J/eta$ production at SPD energies.

Abstract

We investigate inclusive $J/\psi$ production in proton-proton collisions at tens of GeV $\sqrt{s}$ energy, relevant for forthcoming measurements with the Spin Physics Detector (SPD) at NICA. Simulations are performed using the PEGASUS event generator with transverse-momentum-dependent (TMD) gluon densities, comparing the recent KMR-based KL$'2025$ and CCFM-based LLM$'2024$ parametrizations. Differential cross sections in rapidity and transverse momentum exhibit smooth, stable behavior under renormalization-scale variation. Normalized $p_T$ spectra reveal distinct hardening patterns linked to the underlying gluon $k_T$ broadening in each model. The relative contributions of color-singlet and color-octet channels are also quantified, demonstrating the dominance of color-octet mechanisms in the SPD energy regime. These results provide the first detailed assessment of quarkonium production sensitivity to gluon TMDs near threshold, offering timely theoretical guidance for upcoming $J/\psi$ measurements at SPD/NICA.