Measurements of inclusive jet spectra in pp and central Pb-Pb collisions at sNN=5.02TeV

Abstract

This article reports measurements of the p T -differential inclusive jet cross section in pp collisions at √ s = 5.02 TeV and the p T -differential inclusive jet yield in Pb-Pb 0-10% central collisions at √ s NN = 5.02 TeV. Jets were reconstructed at midrapidity with the ALICE tracking detectors and electromagnetic calorimeter using the anti-k T algorithm. For pp collisions, we report jet cross sections for jet resolution parameters R = 0.1-0.6 over the range 20 < p T,jet < 140 GeV/c, as well as the jet cross-section ratios of different R and comparisons to two next-to-leading-order (NLO)-based theoretical predictions. For Pb-Pb collisions, we report the R = 0.2 and R = 0.4 jet spectra for 40 < p T,jet < 140 GeV/c and 60 < p T,jet < 140 GeV/c, respectively. The scaled ratio of jet yields observed in Pb-Pb to pp collisions, R AA , is constructed, and exhibits strong jet quenching and a clear p T dependence for R = 0.2. No significant R dependence of the jet R AA is observed within the uncertainties of the measurement. These results are compared to several theoretical predictions.

Jet Suppression From a Small to Intermediate to Large Radius

“…Even though wider jets lose more energy, they can also recapture a larger fraction of the "lost" energy. These competing effects yield a radius dependence which is relatively flat, specially at the highest jet momenta at LHC (see [16]), in resonance with what has been recently measured in experiments [22][23][24][25]. We have observed that the diffusion wake of one jet can affect the other, inducing energy loss due to an over-subtraction effect, if the jets are relatively aligned in rapidity.…”

Overview of the latest jet physics results from ALICE

“…Figure 1 (right) shows a comparison of these measurements to NNLO calculations [6] as well as to POWHEG+PYTHIA8 [8,9]. These predictions are consistent with the data for all and T, jet , and along with other comparisons [1] demonstrate the importance of NNLO effects and NLL resummations. We additionally reported jet cross-section ratios of different , which allow one to elucidate higher-precision effects of the -dependence of the inclusive jet cross-section.…”

“…Inclusive jet measurements at low-T as a function of provide tests of the perturbative and nonperturbative (NP) contributions to the inclusive jet cross-section [1,2]. First-principles calculations of the perturbative cross-section were recently computed at NLO with resummation of large logarithms [3][4][5], and to NNLO at fixed order [6,7].…”

“…ALICE recently reported inclusive jet cross-sections for jet resolution parameters = 0.1 − 0.6 over the range 20 < T, jet < 140 GeV/ , shown in Fig. 1 (left) [1]. By covering a large range of down to low T , these measurements span a range of perturbative regimes including smallresummation, and a wide range of NP effects (from hadronization-dominated at small to UE-dominated at large ), which can be used to further constrain NP effects in pp collisions.…”

Dependence of inclusive jet production on the anti-kT distance parameter in pp collisions at $$ \sqrt{\mathrm{s}} $$ = 13 TeV

“…We explore this topic further in the present paper by extending the measurement to various values of jet size. Recently, ALICE collaboration has also measured both the absolute cross sections of inclusive jet production and the ratio of cross sections for R = 0.1-0.6 in 20 < p T < 140 GeV [24]. Dependence of inclusive jet production on the distance parameter is also studied in detail in ref.…”