Longitudinal momentum fraction of heavy-flavor mesons in jets in high-energy nuclear collisions
Yao Li, Sa Wang, Ben-Wei Zhang
Abstract
Heavy-flavor jets are powerful tools to gain insight into the in-medium partonic energy-loss mechanisms and the quark-gluon plasma's (QGP) transport properties in high-energy nuclear collisions. In this work we present the first theoretical study of the longitudinal momentum fraction ${z}_{||}$ carried by heavy-flavor mesons in jets in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{{s}_{\mathrm{NN}}}=5.02\phantom{\rule{0.16em}{0ex}}\mathrm{TeV}$. The $\mathrm{p}+\mathrm{p}$ baseline is provided by powheg$+\mathrm{p}$ythia8, which matches the next-to-leading-order hard processes with the parton shower. We employ a Monte Carlo transport model, which considers the collisional and radiative partonic energy loss, to simulate the evolution of heavy-flavor jets in the expanding QGP medium. We observe steeper ${z}_{||}$ distributions of ${\mathrm{B}}^{0}$ jets compared to those of ${\mathrm{D}}^{0}$ jets at the same kinematics region in $\mathrm{p}+\mathrm{p}$ collisions, which may be a hint of the harder jet fragmentation function of b jets compared to c jets in vacuum. In $\mathrm{A}+\mathrm{A}$ collisions, it is shown that the jet quenching effect would generally decrease the values of ${z}_{||}$. We have made a systematical study on how several factors, including jet ${p}_{\mathrm{T}}$, jet radius $R$, and collision centrality, would influence the medium modification of ${z}_{||}$ distributions of a ${\mathrm{D}}^{0}$ jet. In addition, we predict visibly stronger nuclear modifications of ${\mathrm{B}}^{0}$-jet ${z}_{||}$ distributions compared to a ${\mathrm{D}}^{0}$ jet within the same ${p}_{\mathrm{T}}$ windows as a result of the much steeper initial ${z}_{||}$ distribution of the ${\mathrm{B}}^{0}$ jet in vacuum.