Energy-energy correlators in p-Pb collisions at sqrt{s_(rm NN)} = 5.02 TeV
Pith reviewed 2026-06-26 21:39 UTC · model grok-4.3
The pith
The two-point energy-energy correlator in p-Pb jets shows an enhancement at large angles and suppression at small angles relative to pp collisions in the 20-40 GeV/c range.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The two-point energy-energy correlator measured inside charged-particle jets in p-Pb collisions at √s_NN = 5.02 TeV exhibits a modification relative to pp collisions at the same energy, specifically in the 20-40 GeV/c jet transverse momentum interval, consisting of an enhancement at large opening angles and a suppression at small angles; this difference is studied as a function of jet pT, rapidity, and forward activity to constrain cold nuclear matter effects.
What carries the argument
The two-point energy-energy correlator (EEC), an infrared- and collinear-safe measure of angular energy flow within jets.
If this is right
- The observed modification depends on jet transverse momentum.
- The size of the difference also varies with jet rapidity and forward activity.
- The results supply new experimental constraints on cold nuclear matter effects in jet structure.
- These constraints are relevant for separating initial-state and final-state contributions when interpreting EEC data in heavy-ion collisions.
Where Pith is reading between the lines
- If the same angular pattern appears in other jet substructure observables, it would suggest a broad impact of cold nuclear matter on jet evolution.
- Measurements at different collision energies could test whether the modification scales with the available center-of-mass energy per nucleon.
- The rapidity and forward-activity dependence offers a handle to separate effects from the nuclear wave function versus final-state interactions.
Load-bearing premise
The pp reference at the same center-of-mass energy supplies an accurate baseline free of nuclear effects and all detector, reconstruction, and unfolding corrections have been applied identically in both systems.
What would settle it
A new or re-unfolded measurement of the EEC distributions in pp collisions at 5.02 TeV that agrees with the p-Pb distributions within uncertainties in the 20-40 GeV/c interval would falsify the reported modification.
Figures
read the original abstract
This paper presents the first measurement of the two-point energy-energy correlator (EEC) inside charged-particle jets in p-Pb collisions at $\sqrt{s_{\rm NN}} = 5.02$ TeV with the ALICE experiment. The two-point EEC, an infrared- and collinear-safe measure of angular energy flow within jets, is used to probe both perturbative and non-perturbative stages of the jet evolution. The EEC is reported in 20-80 GeV/$c$ jets in p-Pb collisions and compared to a measurement of the EEC in pp events at $\sqrt{s} = 5.02$ TeV. A modification is observed in the 20-40 GeV/$c$ interval, with an enhancement at large opening angles and a suppression at small angles relative to pp collisions. The dependence of this modification on jet transverse momentum, rapidity, and forward activity is investigated. These results provide new constraints on cold nuclear matter effects relevant for disentangling initial- and final-state contributions to jet-structure modifications. An understanding of these cold nuclear matter effects is also relevant for interpreting EEC measurements in heavy-ion collisions.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript reports the first measurement of the two-point energy-energy correlator (EEC) inside charged-particle jets in p-Pb collisions at √s_NN = 5.02 TeV using the ALICE detector. The EEC is measured for jets in the 20-80 GeV/c range and compared to a pp reference at the same center-of-mass energy per nucleon, with a modification observed specifically in the 20-40 GeV/c interval (enhancement at large angles, suppression at small angles). Dependencies on jet p_T, rapidity, and forward activity are also examined to constrain cold-nuclear-matter effects.
Significance. If the reported difference is robust, the result supplies a valuable experimental baseline for cold-nuclear-matter modifications to jet substructure using an infrared- and collinear-safe observable. This is directly relevant for interpreting EEC measurements in heavy-ion collisions and for separating initial- from final-state effects. The direct comparison to a pp data set at matching √s is the conventional approach and avoids circularity.
minor comments (3)
- The abstract states that the pp reference is at √s = 5.02 TeV; the manuscript should explicitly confirm in the methods section that the identical jet-finding, track selection, and unfolding procedures were applied to both systems (as implied by the comparison).
- Figure captions and text should clarify the precise definition of the EEC observable (e.g., the normalization and the angular variable range) to allow direct comparison with future theoretical calculations.
- The dependence on forward activity is mentioned; a brief statement on how the centrality or multiplicity estimator is defined and whether it correlates with the observed modification would improve clarity.
Simulated Author's Rebuttal
We thank the referee for the positive assessment of our manuscript, the recognition of its significance as the first EEC measurement in p-Pb collisions, and the recommendation for minor revision. No major comments were raised in the report.
Circularity Check
No significant circularity
full rationale
This is a direct experimental measurement of the two-point energy-energy correlator in charged-particle jets in p-Pb collisions, compared to a separate pp reference dataset at matching per-nucleon energy. The reported modification is an observational result obtained via standard detector corrections, unfolding, and identical analysis procedures applied to both systems; no equations, ansatze, or fitted parameters are derived that reduce by construction to the inputs. The pp baseline is an independent measurement, not a self-referential fit. The derivation chain is therefore self-contained against external data benchmarks with no load-bearing self-citation loops or definitional circularity.
Axiom & Free-Parameter Ledger
Reference graph
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