Shear viscosity in the Nambu–Jona-Lasinio model with<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>Φ</mml:mi></mml:math>-derivable approximations
Bibliographic record
Abstract
Within the Nambu--Jona-Lasinio model the temperature dependence of the shear viscosity is calculated to the first nontrivial order in the $1/{N}_{c}$ expansion with $\ensuremath{\Phi}$-derivable approximations. The two-particle irreducible effective action is computed to next-to-leading order, from which the integral equations for the 3- and 4-point vertices are obtained. These sum infinite sets of diagrams contributing to the shear viscosity at the same order in the $1/{N}_{c}$ expansion. We find that the shear viscosity decreases rapidly when the chiral crossover is approached. Comparing with the hadron phase, the quark-gluon plasma phase has a low shear viscosity, which is consistent with the measurements. The ratio of the shear viscosity to entropy density is also calculated.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
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; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
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".