Ungroomed $\lambda_{\alpha=3}^{\kappa=1}$ for $R=0.2$ charged-particle jets in $80 < p_\text{T}^\text{ch jet} < 100$ GeV/$c$ in Pb-Pb collisions at $\sqrt{s_\text{NN}}=5.02$ TeV as compared to pp baseline

Scope: PWG
PWG-JE (Jets)
Energy
5.02 TeV
System
p-p
Pb-Pb
Figure Image
Figure image (.eps)
Figure image (.pdf)
Figure Caption

Ungroomed jet angularity with $\alpha = 3$ for $R=0.2$ charged-particle jets in $80 < p_\text{T}^\text{ch jet} < 100$ GeV/$c$ in Pb-Pb collisions at $\sqrt{s_\text{NN}}=5.02$ TeV as compared to various models. On the top panel, the solid black data points and associated vertical error bars correspond to the ALICE Pb-Pb measurement and its statistical uncertainties, with the solid grey boxes corresponding to the Pb-Pb measurement systematic uncertainties; the empty points represent the ALICE pp measurement, and the dashed boxes the pp measurement systematic uncertainties. On the bottom panel, each model is presented with respect to its respective pp baseline, and a box is drawn corresponding to the purely statistical uncertainties of the model calculations, assuming that the pp and Pb-Pb calculations are statistically uncorrelated. The ratio between the ALICE pp and Pb-Pb data similarly assumes that all uncertainties are uncorrelated between the two different systems.

Two predictions using the JEWEL event generator [1] are shown, which is based on a modified version of PYTHIA6. Events are generated with formation time $t_i = 0.4$ fm and initial temperature $T_i = 590$ MeV. In the "recoils off" case, recoiling medium partons are discarded from the event. In the "recoils on" case, medium partons are allowed to hadronize together with the jet, and recoil effects are subtracted by clustering the jets using the negative energy recombination scheme in which the four momenta of "event particles" are added together in the recombination step, and the four momenta of "thermal particles" is subtracted.  The Higher-Twist parton energy loss approach to jet quenching [2] is shown, using POWHEG [3] with PYTHIA [4] matching at NLO as a baseline; a prediction using JETSCAPE [5] is given, with an in-medium parton shower described by the MATTER [6] (high-virtuality regime) and LBT [7] (low-virtuality regime) models; finally, predictions using the Hybrid model [8] both with and without elastic Molière scattering [9] are also given.

[1] Eur. Phys. J. C 74 (2) (2014) 2762, arXiv:1311.0048 [hep-ph]
[2] Chin. Phys. C45 (2021) no. 2, 024102, arXiv:2005.01093 [hep-ph]
[3] Nucl. Phys. Proc. Suppl. 205-206:36-41 (2010), arXiv:1007.3893 [hep-ph]
[4] Comput. Phys. Commun. 191 (Jun, 2015) 159–177, arXiv:1410.3012 [hep-ph]
[5] arXiv:1903.07706 [nucl-th]
[6] Phys. Rev. C 88 (2013) 014909, arXiv:1301.5323 [nucl-th]
[7] Phys. Rev. C 91 (2015) 054908, arXiv:1503.03313 [nucl-th]
[8] arXiv:1405.3864 [hep-ph]
[9] JHEP 01 (2019) 172, arXiv:1808.03250 [hep-ph]