Transverse momentum balance of dijets in Xe+Xe collisions at the LHC

Yao Li; Shu-Wan Shen; Sa Wang; Ben-Wei Zhang

doi:10.1007/s41365-024-01482-6

paper

Transverse momentum balance of dijets in Xe+Xe collisions at the LHC

arXiv:2401.01706 · doi:10.1007/s41365-024-01482-6

Abstract

We present a theoretical study of the medium modifications of the $p_{T}$ balance ( $x_{J}$ ) of dijets in Xe+Xe collisions at $s_{N N} = 5.44$ TeV. The initial production of dijets was carried out using the POWHEG+PYTHIA8 prescription, which matches the next-to-leading-order (NLO) QCD matrix elements with the parton shower (PS) effect. The SHELL model described the in-medium evolution of nucleus-nucleus collisions using a transport approach. The theoretical results of the dijet $x_{J}$ in the Xe+Xe collisions exhibit more imbalanced distributions than those in the p+p collisions, consistent with recently reported ATLAS data. By utilizing the Interleaved Flavor Neutralisation, an infrared-and-collinear-safe jet flavor algorithm, to identify the flavor of the reconstructed jets, we classify dijets processes into three categories: gluon-gluon ( $g g$ ), quark-gluon ( $q g$ ), and quark-quark ( $q q$ ), and investigated the respective medium modification patterns and fraction changes of the $g g$ , $q g$ , and $q q$ components of the dijet sample in Xe+Xe collisions. It is shown that the increased fraction of $q g$ component at a small $x_{J}$ contributes to the imbalance of the dijet; in particular, the $q_{1} g_{2}$ (quark-jet-leading) dijets experience more significant asymmetric energy loss than the $g_{1} q_{2}$ (gluon-jet-leading) dijets traversing the QGP. By comparing the $Δ ⟨ x_{J} ⟩ = ⟨ x_{J} ⟩_{pp} - ⟨ x_{J} ⟩_{AA}$ of inclusive, $c c ˉ$ and $b b ˉ$ dijets in Xe+Xe collisions, we observe $Δ ⟨ x_{J} ⟩_{in c l .} > Δ ⟨ x_{J} ⟩_{c c ˉ} > Δ ⟨ x_{J} ⟩_{b b ˉ}$ . Moreover, $ρ_{X e, P b}$ , the ratios of the nuclear modification factors of dijets in Xe+Xe to those in Pb+Pb, were calculated, which indicates that the yield suppression of dijets in Pb+Pb is more pronounced than that in Xe+Xe owing to the larger radius of the lead nucleus.

arXiv comment8 pages, 6 figures

Transverse momentum balance of dijets in Xe+Xe collisions at the LHC

Abstract

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