Energy scales in a holographic black hole and conductivity at finite momentum
Bibliographic record
Abstract
In this work we discuss the low temperature (T) behavior of gauge field correlators with finite momentum (k) in a AdS4 black hole background. At low temperature, a substantial nonzero conductivity is only possible for a frequency range ω > ωg = k. This tallies with the simple fact that at least an amount of energy ωg is needed to create an excitation of momentum k. Due to the existence of this “gap”, one may expect that at the zero frequency limit the real part of momentum-dependent conductivity falls exponentially with 1/T. Using analytic methods, we found a exp(–ωc/T) falloff of the real part of conductivity with inverse temperature. Interestingly, ωg ≠ ωc. From the above results, we speculate that the “degrees of freedom”, say carriers, different than quasiparticle excitation determines conductivity at the low temperature and the low-frequency limit. Here ωc < ωg, and we may calculate their ratios analytically. We also discuss similar issues at a finite chemical potential. The situation is rather different for an extremal blackhole. A zero temperature extremal blackhole does not show a sharp gap for the finite momentum excitations, and the real part of the conductivity is always nonzero for any nonzero frequency ω. However, the real part of the conductivity goes to zero at the ω → 0 limit. Not surprisingly, we find a power-law decay with temperature for the same quantity, as the extremal limit is approached.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.001 | 0.004 |
| Scholarly communication | 0.002 | 0.003 |
| 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".