2014/01/31 by Redamy Pérez-Ramos, Redamy Perez Ramos, Thorsten Renk
Mathematics · Physics and Astronomy · #Cascade #Collimated light #DGLAP #Geometry #High-Energy Particle Collisions Research #Jet (fluid) #Logarithm #Mathematics #Mechanics #Nuclear physics #Optics #Particle physics #Particle physics theoretical and experimental studies #Parton #Physics #Quantum Chromodynamics and Particle Interactions #Quantum chromodynamics #Scaling #hep-ph
paper · pdf · doi:10.1103/physrevd.90.014018
published as Phys. Rev. D 90, 014018 (2014) · 27 pages and 15 figures. Revised version of the manuscript to be published in Phys. Rev. D
arxiv created 2014/06/26 · openalex publication_date 2014/07/10 · arxiv updated 2014/07/16 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present the medium-modified energy collimation in the leading-logarithmic approximation (LLA) and next-to-leading-logarithmic approximation (NLLA) of QCD. As a consequence of more accurate kinematic considerations in the argument of the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) fragmentation functions (FFs) we find a new NLLA correction O(\ensuremathαs) which accounts for the scaling violation of DGLAP FFs at small x. The jet shape is derived from the energy collimation within the same approximations and we also compare our calculations for the energy collimation with the event generators pythia6 and YaJEM for the first time in this paper. The modification of jets by the medium in both cases is implemented by altering the infrared sector using the Borghini-Wiedemann model. The energy collimation and jet shapes qualitatively describe a clear broadening of showers in the medium, which is further supported by YaJEM in the final comparison of the jet shape with CMS PbPb data at center-of-mass energy 2.76 TeV. The comparison of the biased versus unbiased YaJEM jet shape with the CMS data shows a more accurate agreement for biased showers and illustrates the importance of an accurate simulation of the experimental jet-finding strategy.