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Nuclear modification factors for jet fragmentation

Authors :: Gregory Soyez
Paul Caucal
Alfred H. Mueller
Edmond Iancu
Institut de Physique Théorique - UMR CNRS 3681 (IPHT)
Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)
ANR-16-CE31-0019,DenseQCDatLHC,Etude du régime de haute densité partonique de QCD dans les collisions hadroniques au LHC(2016)
Source :: Journal of High Energy Physics, JHEP, JHEP, 2020, 10, pp.204. ⟨10.1007/JHEP10(2020)204⟩, Journal of High Energy Physics, 2020, 10, pp.204. ⟨10.1007/JHEP10(2020)204⟩, Journal of High Energy Physics, Vol 2020, Iss 10, Pp 1-46 (2020)
Publication Year :: 2020
Publisher :: Springer Science and Business Media LLC, 2020.
Abstract: Using a recently-developed perturbative-QCD approach for jet evolution in a dense quark-gluon plasma, we study the nuclear modification factor for the jet fragmentation function. The qualitative behaviour that we find is in agreement with the respective experimental observations in Pb+Pb collisions at the LHC: a pronounced nuclear enhancement at both ends of the spectrum. Our Monte Carlo simulations are supplemented with analytic estimates which clarify the physical interpretation of the results. The main source of theoretical uncertainty is the sensitivity of our calculations to a low-momentum cutoff which mimics confinement. To reduce this sensitivity, we propose a new observable, which describes the jet fragmentation into subjets and is infrared-and-collinear safe by construction. We present Monte Carlo predictions for the associated nuclear modification factor together with their physical interpretation.<br />Comment: 37 pages, 11 figures, to appear in JHEP