Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Measurement of the Groomed Jet Radius and Momentum Splitting Fraction in pp and Pb-Pb Collisions at sNN =5.02 TeV

Acharya, S. ; Basu, S. LU orcid ; Christiansen, P. LU ; Matonoha, O. LU ; Nassirpour, A.F. LU orcid ; Ohlson, A. LU ; Oskarsson, A. LU ; Richert, T. LU ; Rueda, O.V. LU and Silvermyr, D. LU orcid , et al. (2022) In Physical Review Letters 128(10).
Abstract
This article presents groomed jet substructure measurements in pp and Pb-Pb collisions at sNN=5.02 TeV with the ALICE detector. The soft drop grooming algorithm provides access to the hard parton splittings inside a jet by removing soft wide-angle radiation. We report the groomed jet momentum splitting fraction, zg, and the (scaled) groomed jet radius, θg. Charged-particle jets are reconstructed at midrapidity using the anti-kT algorithm with resolution parameters R=0.2 and R=0.4. In heavy-ion collisions, the large underlying event poses a challenge for the reconstruction of groomed jet observables, since fluctuations in the background can cause groomed parton splittings to be misidentified. By using strong grooming conditions to reduce... (More)
This article presents groomed jet substructure measurements in pp and Pb-Pb collisions at sNN=5.02 TeV with the ALICE detector. The soft drop grooming algorithm provides access to the hard parton splittings inside a jet by removing soft wide-angle radiation. We report the groomed jet momentum splitting fraction, zg, and the (scaled) groomed jet radius, θg. Charged-particle jets are reconstructed at midrapidity using the anti-kT algorithm with resolution parameters R=0.2 and R=0.4. In heavy-ion collisions, the large underlying event poses a challenge for the reconstruction of groomed jet observables, since fluctuations in the background can cause groomed parton splittings to be misidentified. By using strong grooming conditions to reduce this background, we report these observables fully corrected for detector effects and background fluctuations for the first time. A narrowing of the θg distribution in Pb-Pb collisions compared to pp collisions is seen, which provides direct evidence of the modification of the angular structure of jets in the quark-gluon plasma. No significant modification of the zg distribution in Pb-Pb collisions compared to pp collisions is observed. These results are compared with a variety of theoretical models of jet quenching, and provide constraints on jet energy-loss mechanisms and coherence effects in the quark-gluon plasma. © 2022 CERN. (Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; ; and , et al. (More)
; ; ; ; ; ; ; ; ; and (Less)
author collaboration
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Angular distribution, Binary alloys, Energy dissipation, Heavy ions, Tellurium compounds, Grooming algorithms, Jet momentum, Measurements of, Mid-rapidity, Particle jets, Pb-Pb collisions, Quark-gluon plasma, Resolution parameters, Splittings, Wide angle, Colliding beam accelerators
in
Physical Review Letters
volume
128
issue
10
article number
102001
publisher
American Physical Society
external identifiers
  • scopus:85126714754
  • pmid:35333086
ISSN
0031-9007
DOI
10.1103/PhysRevLett.128.102001
language
English
LU publication?
yes
id
0226a6b9-9ff8-475a-bb4a-ba081f02f602
date added to LUP
2022-04-07 10:53:28
date last changed
2023-04-02 22:44:35
@article{0226a6b9-9ff8-475a-bb4a-ba081f02f602,
  abstract     = {{This article presents groomed jet substructure measurements in pp and Pb-Pb collisions at sNN=5.02 TeV with the ALICE detector. The soft drop grooming algorithm provides access to the hard parton splittings inside a jet by removing soft wide-angle radiation. We report the groomed jet momentum splitting fraction, zg, and the (scaled) groomed jet radius, θg. Charged-particle jets are reconstructed at midrapidity using the anti-kT algorithm with resolution parameters R=0.2 and R=0.4. In heavy-ion collisions, the large underlying event poses a challenge for the reconstruction of groomed jet observables, since fluctuations in the background can cause groomed parton splittings to be misidentified. By using strong grooming conditions to reduce this background, we report these observables fully corrected for detector effects and background fluctuations for the first time. A narrowing of the θg distribution in Pb-Pb collisions compared to pp collisions is seen, which provides direct evidence of the modification of the angular structure of jets in the quark-gluon plasma. No significant modification of the zg distribution in Pb-Pb collisions compared to pp collisions is observed. These results are compared with a variety of theoretical models of jet quenching, and provide constraints on jet energy-loss mechanisms and coherence effects in the quark-gluon plasma. © 2022 CERN.}},
  author       = {{Acharya, S. and Basu, S. and Christiansen, P. and Matonoha, O. and Nassirpour, A.F. and Ohlson, A. and Oskarsson, A. and Richert, T. and Rueda, O.V. and Silvermyr, D. and Zurlo, N.}},
  issn         = {{0031-9007}},
  keywords     = {{Angular distribution; Binary alloys; Energy dissipation; Heavy ions; Tellurium compounds; Grooming algorithms; Jet momentum; Measurements of; Mid-rapidity; Particle jets; Pb-Pb collisions; Quark-gluon plasma; Resolution parameters; Splittings; Wide angle; Colliding beam accelerators}},
  language     = {{eng}},
  number       = {{10}},
  publisher    = {{American Physical Society}},
  series       = {{Physical Review Letters}},
  title        = {{Measurement of the Groomed Jet Radius and Momentum Splitting Fraction in pp and Pb-Pb Collisions at sNN =5.02 TeV}},
  url          = {{http://dx.doi.org/10.1103/PhysRevLett.128.102001}},
  doi          = {{10.1103/PhysRevLett.128.102001}},
  volume       = {{128}},
  year         = {{2022}},
}