Alexander Snigirev | Searcharxiv

arXiv2025

Probing Azimuthal Alignment in Heavy-Ion Collisions: Clusterization Effects

The influence of kinematic constraints and event selection on the emergence of the alignment phenomenon observed in cosmic-ray experiments is studied within the HYDJET++ model. It is demonstrated that the high degree of alignment, previously identified for realistic values of the transverse momentum disbalance of the most energetic particles, is also observed at the level of the most energetic clusters. In high-multiplicity events, the clustering procedure plays a crucial role in resolving individual particle groups on the detection plane, allowing a more accurate characterization of alignment patterns. These results highlight the combined effects of cluster formation and momentum conservation in shaping the observed azimuthal correlations.

hep-ph↗

arXiv2017

Double, triple, and $n$-parton scatterings in high-energy proton and nuclear collisions

The framework to compute the cross sections for the production of particles with high mass and/or large transverse momentum in double- (DPS), triple- (TPS), and in general $n$-parton scatterings, from the corresponding single-parton ($σ_{\rm SPS}$) values in high-energy proton-proton, proton-nucleus, and nucleus-nucleus is reviewed. The basic parameter of the factorized $n$-parton scattering ansatz is an effective cross section $σ_{\rm eff}$ encoding all unknowns about the underlying generalized $n$-parton distribution in the proton (nucleon). In its simplest and most economical form, the $σ_{\rm eff}$ parameter can be derived from the transverse parton profile of the colliding protons and/or nucleus, using a Glauber approach. Numerical examples for the cross sections and yields expected for the concurrent DPS or TPS production of heavy-quarks, quarkonia, and/or gauge bosons in proton and nuclear collisions at LHC and Future Circular Collider (FCC) energies are provided. The obtained cross sections are based on perturbative QCD predictions for $σ_{\rm SPS}$ at next-to-leading-order (NLO) or next-to-NLO (NNLO) accuracy including, when needed, nuclear modifications of the corresponding parton densities.

hep-ph↗