Debye mass from domainwalls and dimensionally reduced phase diagram

To measure the Debye mass in dimensionally reduced QCD for $N_c\le 3$ we replace in the correlator of two Polyakov loops one of the loops by a wall triggered by a dimensionally reduced twist. The phase diagram for $N_c=3$ has R-parity broken in part of the Higgs phase.Comment: LATTICE98(hightemp

Heavy flavor diffusion in weakly coupled N=4 Super Yang-Mills theory

We use perturbation theory to compute the diffusion coefficient of a heavy quark or scalar moving in N=4 SU(N_c) Super Yang-Mills plasma to leading order in the coupling and the ratio T/M<<1. The result is compared both to recent strong coupling calculations in the same theory and to the corresponding weak coupling result in QCD. Finally, we present a compact and simple formulation of the Lagrangian of our theory, N=4 SYM coupled to a massive fundamental N=2 hypermultiplet, which is well-suited for weak coupling expansions.Comment: 22 pages, 4 figures; v3: error corrected in calculations, figures and discussion modified accordingl

Hard thermal loops and the entropy of supersymmetric Yang-Mills theories

We apply the previously proposed scheme of approximately self-consistent hard-thermal-loop resummations in the entropy of high-temperature QCD to N=4 supersymmetric Yang-Mills (SYM) theories and compare with a (uniquely determined) R[4,4] Pad\'e approximant that interpolates accurately between the known perturbative result and the next-to-leading order strong-coupling result obtained from AdS/CFT correspondence. We find good agreement up to couplings where the entropy has dropped to about 85% of the Stefan-Boltzmann value. This is precisely the regime which in purely gluonic QCD corresponds to temperatures above 2.5 times the deconfinement temperature and for which this method of hard-thermal-loop resummation has given similar good agreement with lattice QCD results. This suggests that in this regime the entropy of both QCD and N=4 SYM is dominated by effectively weakly coupled hard-thermal-loop quasiparticle degrees of freedom. In N=4 SYM, strong-coupling contributions to the thermodynamic potential take over when the entropy drops below 85% of the Stefan-Boltzmann value.Comment: 14 pages, 2 figures, JHEP3. v2: revised and expanded, with unchanged HTL results but corrected NLO strong-coupling result from AdS/CFT (which is incorrectly reproduced in almost all previous papers comparing weak and strong coupling results of N=4 SYM) and novel (unique) Pade approximant interpolating between weak and strong coupling result

Covariant derivative expansion of fermionic effective action at high temperatures

We derive the fermionic contribution to the 1-loop effective action for A_4 and A_i fields at high temperatures, assuming that gluon fields are slowly varying but allowing for an arbitrary amplitude of A_4.Comment: RevTex 4, 11 pages, 3 figures. Version 2: Typos corrected; magnetic fields restricted to parallel sector. Version accepted for publication in PR

Spatial 't Hooft loop to cubic order in hot QCD

Spatial 't Hooft loops of strength k measure the qualitative change in the behaviour of electric colour flux in confined and deconfined phase of SU (N) gauge theory. They show an area law in the deconfined phase, known analytica lly to two loop order with a ``k-scaling'' law k(N-k). In this paper we comput e the O(g^3) correction to the tension. It is due to neutral gluon fields that get their mass through interaction with the wall. The simple k-scaling is lost in cubic order. The generic problem of non-convexity shows up in this order an d the cure is provided. The result for large N is explicitely given. We show tha t nonperturbative effects appear at O(g^5).Comment: 22 pages. Apart from a discussion on the renormalization effect of the Polyakov loop to cubic order only cosmetic changes with respect to the earlier hep-ph/021229

Deformations of conformal theories and non-toric quiver gauge theories

We discuss several examples of non-toric quiver gauge theories dual to Sasaki-Einstein manifolds with U(1)^2 or U(1) isometry. We give a general method for constructing non-toric examples by adding relevant deformations to the toric case. For all examples, we are able to make a complete comparison between the prediction for R-charges based on geometry and on quantum field theory. We also give a general discussion of the spectrum of conformal dimensions for mesonic and baryonic operators for a generic quiver theory; in the toric case we make an explicit comparison between R-charges of mesons and baryons.Comment: 51 pages, 12 figures; minor corrections in appendix B, published versio

Screening of Z(N) monopole pairs in gauge theories

The screening of magnetic Z(N)-monopoles and the associated screening length in SU(N) gauge theories are analyzed theoretically, and computed numerically in the 3d SU(2) theory. The nature of the screening excitations as well as their mass have so far remained inconclusive in the literature. Here we show that the screening mass is identical to the lowest J^{PC}_R=0^{++}_+ excitation of the Yang-Mills Hamiltonian with one compact direction with period 1/T, the subscript R referring to parity in this direction. We extend the continuum formulation to one on the lattice, and determine the transfer matrix governing the decay of the spatial monopole correlator at any finite lattice spacing. Our numerical results for SU(2) for the screening mass in the dimensionally reduced (high temperature) theory are compatible with the 0^{++} glueball mass in 3d SU(2).Comment: 24 pages, 3 figures. Typos corrected, published versio

Mesonic correlation lengths in high-temperature QCD

We consider spatial correlation lengths \xi for various QCD light quark bilinears at temperatures above a few hundred MeV. Some of the correlation lengths (such as that related to baryon density) coincide with what has been measured earlier on from glueball-like states; others do not couple to glueballs, and have a well-known perturbative leading-order expression as well as a computable next-to-leading-order correction. We determine the latter following analogies with the NRQCD effective theory, used for the study of heavy quarkonia at zero temperature: we find (for the quenched case) \xi^{-1} = 2 \pi T + 0.1408 g^2 T, and compare with lattice results. One manifestation of U_A(1) symmetry non-restoration is also pointed out.Comment: 25 pages. v2: small clarifications; published versio

't Hooft and Wilson loop ratios in the QCD plasma

The spatial 't Hooft loop measuring the electric flux and the spatial Wilsonloop measuring the magnetic flux are analyzed in hot SU(N) gauge theory. Both display area laws. On one hand the tension of the 't Hooft loop is perturbatively calculable, in the same sense as the pressure. We show that the O(g^3) contribution is absent. The ratio of multi-charged 't Hooft loops have a remarkably simple dependence on the charge, true up to, but not including, O(g^4). This dependence follows also from a simple model of free screened colour charges. On the other hand the surface tension of the Wilsonloop is non-perturbative. But in a model of screened free monopoles at very high temperature the known area law follows. The density of these monopoles starts to contribute to O(g^6) to the pressure. The ratio of the multicharged Wilson loops is calculable and identical to that of the 't Hooft loops.Comment: 28 pages, 8 figure