QCD in magnetic field, Landau levels and double-life of unbroken center-symmetry
Bibliographic record
Abstract
We study the thermal confinement/deconfinement and non-thermal quantum phase transitions or rapid cross-overs in QCD and QCD-like theories in external magnetic fields. At large magnetic fields, while the contribution of gauge fluctuations to Wilson-line potential remains unaltered at one-loop order, the contribution of fermions effectively becomes two lower dimensional and is enhanced by the density of states of the lowest Landau level (LLL). In a spatial compactification and for heavy adjoint fermions, this enhancement leads to a calculable zero temperature quantum phase transition on $$ {\mathbb{R}}^3\times {\mathbb{S}}^1 $$ driven by a competition between the center-destabilizing gauge contribution and center-stabilizing LLL fermions. We also show that at a (formal) asymptotically large magnetic field, the adjoint fermions with arbitrarily large but fixed mass stabilize the center symmetry. This is an exotic case of simultaneous non-decoupling of large mass fermions (due to the enhancement by the LLL density of states) and decoupling from the low energy effective field theory. This observation has important implications for both Hosotani mechanism, for which gauge symmetry “breaking” occurs, and large-N volume independence (Eguchi-Kawai reduction), for which gauge structure is never “broken”. Despite sounding almost self-contradictory, we carefully explain the physical scales entering the problem, double-meaning of unbroken center symmetry and how a clash is avoided. We also identify, for both thermal and spatial compactification, the jump in magnetic susceptibility as an order parameter for the deconfinement transition. The predictions of our analysis are testable by using current lattice techniques.
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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 | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.001 | 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".