Fluctuations and asymmetric jet events in PbPb collisions at the LHC

Gavin P. Salam; Gregory Soyez; Matteo Cacciari

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Fluctuations and asymmetric jet events in PbPb collisions at the LHC

Matteo Cacciari, Gavin P. Salam, Gregory Soyez

High Energy Physics - Phenomenology · Submitted 14 Jan 2011

abstract compiled · 2026-09-23 · no language-model review

The authors' main claim Our results suggest that a detailed estimate of the true fluctuations would be of benefit in extracting quantitative information about jet quenching.

how it is stated · hedged possibility 1.00 read the record →

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arXiv ID1101.2878 (version 2)

Pith IDEXWNCIA4, Pith's permanent record of this paper and its review

CitationGavin P. Salam, Gregory Soyez, Matteo Cacciari. "Fluctuations and asymmetric jet events in PbPb collisions at the LHC." arXiv:1101.2878 (2011). https://pith.science/paper/EXWNCIA4

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What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.73 · human participants 0.01 · controlled comparison 0.12 · randomized assignment 0.01 · states quantitative result 0.05 · compares with prior results 0.24 · mentions code or data availability 0.02.

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Recent LHC results concerning full jet-quenching in PbPb collisions have been presented in terms of a jet asymmetry parameter, measuring the imbalance between the transverse momenta of leading and subleading jets. We examine the potential sensitivity of this distribution to fluctuations from the heavy-ion background. Our results suggest that a detailed estimate of the true fluctuations would be of benefit in extracting quantitative information about jet quenching. We also find that the apparent impact of fluctuations on the jet asymmetry distribution can depend significantly on the choice of low-pt threshold used for the simulation of the hard pp events.

background contribution method result interpretation main claim

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#	sentence	role	the authors' own work	states the main conclusion	strength
s0	Recent LHC results concerning full jet-quenching in PbPb collisions have been presented in terms of a jet asymmetry parameter, measuring the imbalance between the transverse momenta of leading and subleading jets.	background 1.00	0.05	0.04	asserted 1.00
s1	We examine the potential sensitivity of this distribution to fluctuations from the heavy-ion background.	contribution 0.98	0.49	0.04	hedged possibility 0.87
s2	Our results suggest that a detailed estimate of the true fluctuations would be of benefit in extracting quantitative information about jet quenching.	interpretation 0.75	0.84	0.61	hedged possibility 1.00
s3	We also find that the apparent impact of fluctuations on the jet asymmetry distribution can depend significantly on the choice of low-pt threshold used for the simulation of the hard pp events.	result 0.95	0.94	0.14	asserted 0.95

What kind of paper the classifier reports this is: simulation study 0.98 · evidence from simulation or computation 0.91.

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arXiv listing abstract v2

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full text
figures and tables
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S sections
T body sentences
C citations
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Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

The paper

Original abstract

Recent LHC results concerning full jet-quenching in PbPb collisions have been presented in terms of a jet asymmetry parameter, measuring the imbalance between the transverse momenta of leading and subleading jets. We examine the potential sensitivity of this distribution to fluctuations from the heavy-ion background. Our results suggest that a detailed estimate of the true fluctuations would be of benefit in extracting quantitative information about jet quenching. We also find that the apparent impact of fluctuations on the jet asymmetry distribution can depend significantly on the choice of low-pt threshold used for the simulation of the hard pp events.

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References

Forward citations

Cited by 10 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score. Full citation record

SoftKiller, a particle-level pileup removal method
hep-ph 2014-07 accept novelty 7.0 of 10

A simple event-level particle threshold, chosen so the median-area pileup density is zero, improves jet resolution over area-median subtraction in simulation while running nearly two orders of magnitude faster.
Measurement of charged jet production cross sections and nuclear modification in p-Pb collisions at $\sqrt{s_\rm{NN}} = 5.02$ TeV
nucl-ex 2015-03 accept novelty 6.0 of 10

Charged jet production in proton-lead collisions at 5.02 TeV agrees with a scaled proton-proton reference within uncertainties, so no strong cold nuclear matter effect on jets is seen up to 120 GeV/c.
A perturbative framework for jet quenching
hep-ph 2012-12 conditional novelty 6.0 of 10

Treating medium-induced radiation as ordinary infrared-regulated QCD scattering dressed by parton showers, with parameters fixed at RHIC, reproduces LHC jet-quenching data without retuning.
${\cal O}(\alpha_s^3)$ analysis of inclusive jet and di-jet production in heavy ion reactions at the Large Hadron Collider
hep-ph 2011-05 conditional novelty 6.0 of 10

At next-to-leading order in QCD, roughly a third to a half of the extra di-jet momentum imbalance in central lead-lead collisions at the LHC is attributable to radiative jet quenching, with the remainder plausibly com...
Observation and studies of jet quenching in PbPb collisions at nucleon-nucleon center-of-mass energy = 2.76 TeV
nucl-ex 2011-02 accept novelty 6.0 of 10

In central PbPb collisions at 2.76 TeV, dijets become strongly momentum-imbalanced, and the imbalance is carried by low-momentum particles emitted at large angles to the away-side jet.

Show 5 more citing papers

Jet momentum dependence of jet quenching in PbPb collisions at sqrt(sNN)=2.76 TeV
nucl-ex 2012-02 accept novelty 5.0 of 10

Dijet momentum imbalance in central PbPb collisions at 2.76 TeV persists essentially unchanged up to leading jet transverse momenta above 300 GeV/c, while peripheral collisions match proton-proton data and a no-quench...
Performance of the ALICE Experiment at the CERN LHC
nucl-ex 2014-02 accept novelty 4.0 of 10

ALICE documents the measured performance of its tracking, particle identification, calorimetry, jet and muon systems in LHC Run 1, together with the luminosity calibration that underpins its cross-section measurements.
Dijet asymmetry at the Large Hadron Collider
nucl-th 2011-03 conditional novelty 4.0 of 10

A parton-transport simulation with one tuned coupling reproduces the dijet energy asymmetry measured by CMS, and less well by ATLAS, in central lead-lead collisions at the LHC.
QGP@50: More than Four Decades of Jet Quenching
hep-ph 2025-08 conditional novelty 2.0 of 10

A historical and technical review of jet quenching in heavy-ion collisions, covering four decades of theory, the RHIC discovery, and modern Bayesian extractions of the jet transport parameter qhat.
Heavy-ion collisions at the Large Hadron Collider: a review of the results from Run 1
nucl-ex 2015-11 accept novelty 2.0 of 10

Run 1 at the LHC confirmed that PbPb collisions create a dense, strongly collective, nearly ideal fluid that is opaque to energetic partons, and unexpectedly found collective-like behaviour in high-multiplicity pPb co...

How the literature uses it

24 arXiv papers cite this in 29 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 25 sentences without a confident label

Uses its method or tool 1 paper

Section [ref] describes the event and track selection, the centrality determination, as well as the jet reconstruction, the corrections for uncorrelated background contributing to the jet momentum [ref] and the corrections for detector effects.

Centrality dependence of charged jet production in p-Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 5.02 TeV · Introduction · 0.96

Compares with it 1 paper

In this sense, our result is similar to the argument presented in [ref] that background fluctuations can generate much of the asymmetry observed by ATLAS and CMS.

${\cal O}(\alpha_s^3)$ analysis of inclusive jet and di-jet production in heavy ion reactions at the Large Hadron Collider · Quenching of di-jets and their $E_T$ asymmetry · 0.87

Cites it as support 1 paper

Indeed, it has been noted in [ref] that the fluctuations in a single-event background may affect the dijet energy imbalance and thus the extraction of medium properties and the characterization of the energy loss mechanism.

An analysis of the influence of background subtraction and quenching on jet observables in heavy-ion collisions · Introduction · 0.99

Cites it as background 1 paper

The effect of background fluctuations on jet observables has extensively been discussed in [ref] .

An analysis of the influence of background subtraction and quenching on jet observables in heavy-ion collisions · Background energy and event-by-event fluctuations · 0.95

What it cites · 22 sentences without a confident label

Uses the method or tool of 7 papers

To subtract the background from jets we have taken the area/median method of [ref] , using, for the estimation of the background density, a (rapidity) StripRange of half-width 0.8 centred on the jet to be subtracted, as described in more detail in [ref] .

Pileup subtraction using jet areas · Introduction · 1.00
To subtract the background from jets we have taken the area/median method of [ref] , using, for the estimation of the background density, a (rapidity) StripRange of half-width 0.8 centred on the jet to be subtracted, as described in more detail in [ref] .

The Catchment Area of Jets · Introduction · 1.00
To subtract the background from jets we have taken the area/median method of [ref] , using, for the estimation of the background density, a (rapidity) StripRange of half-width 0.8 centred on the jet to be subtracted, as described in more detail in [ref] .

Jet Reconstruction in Heavy Ion Collisions · Introduction · 1.00

Uses data or values from 1 paper

For example, fig. 4f of [ref] indicates that $40$ jets ($0-10%$ centrality) have about $20%$ resolution, i.e. a $σ_≃8$, well below the largest values that we have discussed here.

Observation and studies of jet quenching in PbPb collisions at nucleon-nucleon center-of-mass energy = 2.76 TeV · The CMS jet-reconstruction procedure · 0.86

Compares with 1 paper

The embedded events come from Pythia version 6.423, tune DW, run at $√(s)=2.76$. gives an average background level of $210$ per unit area for $0-10%$ centrality and $|η|<2.8$, compatible with the average jet contamination found by ATLAS, and an average charged-particle multiplicity for $0-10%$ centrality of 1400 for $|η|<0.5$, which is reasonably consistent with that measured by ALICE [ref] (further comparisons are discussed in appendix [ref]).

Centrality dependence of the charged-particle multiplicity density at mid-rapidity in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV · Introduction · 0.88

Cites as background 4 papers

STAR [ref] and PHENIX [ref] have presented first (preliminary) measurements of full jets produced in AuAu collisions with transverse momenta in the $20-40$ range and found that jet spectra are also suppressed, though by a potentially more modest factor than for hadrons.

First Direct Measurement of Jets in $\sqrt{s_{NN}}=200$ GeV Heavy Ion Collisions by STAR · Introduction · 0.83
STAR [ref] and PHENIX [ref] have presented first (preliminary) measurements of full jets produced in AuAu collisions with transverse momenta in the $20-40$ range and found that jet spectra are also suppressed, though by a potentially more modest factor than for hadrons.

Direct jet reconstruction in p + p and Cu + Cu at PHENIX · Introduction · 0.83
It was not the purpose of this article to discuss the CMS results [ref] , insofar as they appeared subsequent to the first version of this article.

Observation and studies of jet quenching in PbPb collisions at nucleon-nucleon center-of-mass energy = 2.76 TeV · The CMS jet-reconstruction procedure · 0.89

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