Cold Nuclear Matter Effects on Dijet Productions in Relativistic Heavy-ion Reactions at LHC

TL;DR

This paper studies how cold nuclear matter influences dijet production in high-energy heavy-ion collisions at the LHC, revealing that some observables are unaffected by initial-state effects while others show significant modifications.

Contribution

It provides a detailed analysis of CNM effects on various dijet observables using different nuclear parton distribution functions, highlighting their impact on invariant mass and transverse momentum spectra.

Findings

Dijet angular distributions and momentum imbalance are insensitive to CNM effects.

Invariant mass and transverse momentum spectra are enhanced by CNM effects.

Differences among nuclear PDF parametrizations are significant, especially at Pb+Pb collisions.

Abstract

We investigate the cold nuclear matter(CNM) effects on dijet productions in high-energy nuclear collisions at LHC with the next-to-leading order perturbative QCD. The nuclear modifications for dijet angular distributions, dijet invariant mass spectra, dijet transverse momentum spectra and dijet momentum imbalance due to CNM effects are calculated by incorporating EPS, EKS, HKN and DS param-etrization sets of parton distributions in nucleus . It is found that dijet angular distributions and dijet momentum imbalance are insensitive to the initial-state CNM effects and thus provide optimal tools to study the final-state hot QGP effects such as jet quenching. On the other hand, the invariant mass spectra and the transverse momentum spectra of dijet are generally enhanced in a wide region of the invariant mass or transverse momentum due to CNM effects with a feature opposite to the expected suppression because of the final-state parton energy loss effect in the QGP. The difference of EPS, EKS, HKN and DS parametrization sets of nuclear parton distribution functions is appreciable for dijet invariant mass spectra and transverse momentum spectra at p+Pb collisions, and becomes more pronounced for those at Pb+Pb reactions.