Strong Constraints on Jet Quenching in Centrality-Dependent <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>p</mml:mi><mml:mo>+</mml:mo><mml:mi>Pb</mml:mi></mml:mrow></mml:math> Collisions at 5.02 TeV from ATLAS
Bibliographic record
Abstract
Jet quenching is the process of color-charged partons losing energy via interactions with quark-gluon plasma droplets created in heavy-ion collisions. The collective expansion of such droplets is well described by viscous hydrodynamics. Similar evidence of collectivity is consistently observed in smaller collision systems, including $pp$ and $p+\mathrm{Pb}$ collisions. In contrast, while jet quenching is observed in $\mathrm{Pb}+\mathrm{Pb}$ collisions, no evidence has been found in these small systems to date, raising fundamental questions about the nature of the system created in these collisions. The ATLAS experiment at the Large Hadron Collider has measured the yield of charged hadrons correlated with reconstructed jets in $0.36\text{ }\text{ }{\mathrm{nb}}^{\ensuremath{-}1}$ of $p+\mathrm{Pb}$ and $3.6\text{ }\text{ }{\mathrm{pb}}^{\ensuremath{-}1}$ of $pp$ collisions at 5.02 TeV. The yields of charged hadrons with ${p}_{T}^{\mathrm{ch}}>0.5\text{ }\text{ }\mathrm{GeV}$ near and opposite in azimuth to jets with ${p}_{T}^{\text{jet}}>30$ or 60 GeV, and the ratios of these yields between $p+\mathrm{Pb}$ and $pp$ collisions, ${I}_{p\mathrm{Pb}}$, are reported. The collision centrality of $p+\mathrm{Pb}$ events is categorized by the energy deposited by forward neutrons from the struck nucleus. The ${I}_{p\mathrm{Pb}}$ values are consistent with unity within a few percent for hadrons with ${p}_{T}^{\mathrm{ch}}>4\text{ }\text{ }\mathrm{GeV}$ at all centralities. These data provide new, strong constraints that preclude almost any parton energy loss in central $p+\mathrm{Pb}$ collisions.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.002 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.002 | 0.003 |
| Research integrity | 0.001 | 0.003 |
| Insufficient payload (model declined to judge) | 0.010 | 0.006 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; both teacher heads agree on what is shown here.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".