Jet quenching from heavy to light ion collisions

Abstract

We perform an analysis of jet quenching in heavy and light ion collisions for scenarios without and with quark-gluon plasma formation in pp collisions. We find that the results for these scenarios are very similar, and both of them are in reasonable agreement with data for heavy ion collisions. However, their results become differ significantly for light nuclei. Using the parameters fitted to heavy ion data on the nuclear modification factor RAA, we make predictions for 0.2 and 7 TeV O+O collisions that can be verified by future experiments at RHIC and the LHC.

Medium Effects for Hadron-Tagged Jets in Proton–Proton Collisions

“…The results of hydrodynamic analyses of the flow effects support that the QGP is formed at the proper time τ 0 ∼ 0.5 − 1 fm [2,3]. Such a picture of the QGP formation allows one to describe the RHIC and LHC heavy ion data on the nuclear modification factor R AA (see, e.g., [5][6][7]) in the pQCD jet quenching models with dominating contribution to the jet modification from induced gluon emission [8][9][10][11][12][13]. The observation of the ridge effect [14,15] in pp collisions at the LHC energies, suggests that the QGP can be created in pp collisions as well.…”

“…The linear L-dependence of ∆E r for an expanding QGP remains approximately valid also for calculations with accurate treatment of the Coulomb effects with running α s [27]. Calculations of the medium modification factor R pp (which is not directly observable quantity) within the light-cone path integral (LCPI) approach [10] with accurate treatment of the Coulomb effects and running α s give a small deviation of R pp from unity at the LHC energies [7] (R pp ∼ 0.8 at p T ∼ 10 GeV). For this reason observation of jet quenching in pp collisions via a weak modification of the p T -dependence of hadron spectra is practically impossible.…”

“…In the present paper, we carry out such calculations of I pp for hadron-tagged jets for conditions of the ALICE experiment [1] within the LCPI approach [10] to the induced gluon emission. We calculate the medium modified FFs using the LCPI scheme with temperature dependent α s [31] used in our recent global analysis [7] of the data on the nuclear modification factor R AA .…”

“…The averaging over the jet trajectories is implicit in (4) and (5). As in our calculations of R pp in [7], we perform calculations of I pp for an effective azimuthally symmetric mQGP fireball for the whole range of the impact parameter. This approximation is reasonable because we calculate an azimuthally averaged quantity, and anyway the jet production is dominated by pp collisions with small impact parameters.…”

“…This approximation is reasonable because we calculate an azimuthally averaged quantity, and anyway the jet production is dominated by pp collisions with small impact parameters. As in [7], the distribution in the transverse plane of the di-jet production points is evaluated using the MIT bag model quark density (for simplicity we assume that gluons have the same distribution in the transverse plane as quarks).…”