Measurement of the Splitting Function in pp and Pb-Pb Collisions at sNN =5.02 TeV

CMS Collaboration

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Abstract

Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.

Original languageEnglish
Article number142302
JournalPhysical Review Letters
Volume120
Issue number14
DOIs
Publication statusPublished - 2018 Apr 3

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All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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