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Sumit Basu (Lund University)

Sumit Basu

Postdoctoral Researcher

Sumit Basu (Lund University)

First measurements of N-subjettiness in central Pb-Pb collisions at √sNN = 2.76 TeV

Author

  • S Acharya
  • Jonatan Adolfsson
  • Sumit Basu
  • Peter Christiansen
  • Oliver Matonoha
  • Adrian Nassirpour
  • Alice Ohlson
  • Anders Oskarsson
  • Tuva Richert
  • Omar Vazquez Rueda
  • David Silvermyr
  • N Zurlo
Show all

Summary, in English

The ALICE Collaboration reports the first fully-corrected measurements of the N-subjettiness observable for track-based jets in heavy-ion collisions. This study is performed using data recorded in pp and Pb-Pb collisions at centre-of-mass energies of s = 7 TeV and sNN = 2.76 TeV, respectively. In particular the ratio of 2-subjettiness to 1-subjettiness, τ2/τ1, which is sensitive to the rate of two-pronged jet substructure, is presented. Energy loss of jets traversing the strongly interacting medium in heavy-ion collisions is expected to change the rate of two-pronged substructure relative to vacuum. The results are presented for jets with a resolution parameter of R = 0.4 and charged jet transverse momentum of 40 ≤ pT,jet ≤ 60 GeV/c, which constitute a larger jet resolution and lower jet transverse momentum interval than previous measurements in heavy-ion collisions. This has been achieved by utilising a semi-inclusive hadron-jet coincidence technique to suppress the larger jet combinatorial background in this kinematic region. No significant modification of the τ2/τ1 observable for track-based jets in Pb-Pb collisions is observed relative to vacuum PYTHIA6 and PYTHIA8 references at the same collision energy. The measurements of τ2/τ1, together with the splitting aperture angle ∆R, are also performed in pp collisions at s = 7 TeV for inclusive jets. These results are compared with PYTHIA calculations at s = 7 TeV, in order to validate the model as a vacuum reference for the Pb-Pb centre-of-mass energy. The PYTHIA references for τ2/τ1 are shifted to larger values compared to the measurement in pp collisions. This hints at a reduction in the rate of two-pronged jets in Pb-Pb collisions compared to pp collisions. [Figure not available: see fulltext.] © 2021, The Author(s).

Department/s

  • Particle and nuclear physics
  • eSSENCE: The e-Science Collaboration

Publishing year

2021-01-01

Language

English

Publication/Series

Journal of High Energy Physics

Volume

2021

Issue

9

Document type

Journal article

Publisher

Springer

Topic

  • Subatomic Physics

Keywords

  • Heavy Ion Experiments

Status

Published

ISBN/ISSN/Other

  • ISSN: 1029-8479