Transverse Momentum Balance and Angular Distribution of $b\bar{b}$ Dijets in Pb+Pb collisions

TL;DR

This paper investigates the in-medium evolution and energy loss of $bar{b}$ dijets in Pb+Pb collisions, comparing theoretical simulations with experimental data and predicting azimuthal angle distributions.

Contribution

It introduces a comprehensive framework combining NLO+parton shower, Langevin transport, and higher-twist energy loss to study $bar{b}$ dijets in heavy-ion collisions, with novel predictions for azimuthal distributions.

Findings

$bar{b}$ dijets are suppressed due to jet quenching.

The production distribution shifts to smaller $x_J$ in Pb+Pb collisions.

Azimuthal angle distribution shows suppression on the same side and enhancement on the away side.

Abstract

The productions of inclusive b-jet and $b\bar{b}$ dijets in Pb+Pb collisions have been investigated by considering the heavy quark and the light quark in-medium evolution simultaneously. The initial hard processes of inclusive b-jet and $b\bar{b}$ dijets productions are described by a next-to-leading order (NLO) plus parton shower Monte Carlo (MC) event generator SHERPA which can be well-matched with the experimental data in p+p collisions. The framework combines the Langevin transport model to describe the evolution of the bottom quark also its collisional energy loss and the higher-twist description to consider the radiative energy loss of both the bottom and light quarks. We compare the theoretical simulation of inclusive jet and inclusive b-jet $R_{\rm AA}$ in Pb+Pb collisions at $\sqrt{s_{\rm NN}}=2.76$ TeV with the experimental data, and then present the theoretical simulation of the momentum balance of the $b\bar{b}$ dijet in Pb+Pb collisions at $5.02$ TeV with the recent CMS data for the first time. A similar trend as that in inclusive dijets has been observed in $b\bar{b}$ dijets, the production distribution is shifted to smaller $x_J$ due to the jet quenching effect. At last, the prediction of the normalized azimuthal angle distribution of the $b\bar{b}$ dijet in Pb+Pb collisions at $5.02$ TeV has been reported. The medium induced energy loss effect of the $b\bar{b}$ dijets will overall suppress its production, but the same side ($\Delta \phi \to 0$ region) suffers more energy loss than away side ($\Delta \phi \to \pi$ region), therefore lead to the suppression on the same side and the enhancement on the away side in the normalized azimuthal angle distribution in A+A collisions.