arXiv subjects

T. G. Kovács

Publications and source records attributed to T. G. Kovács.

8 recordsLinked to original sources

arXiv2015

Anderson transition and multifractals in the spectrum of the Dirac operator of Quantum Chromodynamics at high temperature

We investigate the Anderson transition found in the spectrum of the Dirac operator of Quantum Chromodynamics (QCD) at high temperature, studying the properties of the critical quark eigenfunctions. Applying multifractal finite-size scaling we determine the critical point and the critical exponent of the transition, finding agreement with previous results, and with available results for the unitary Anderson model. We estimate several multifractal exponents, finding also in this case agreement with a recent determination for the unitary Anderson model. Our results confirm the presence of a true Anderson localization-delocalization transition in the spectrum of the quark Dirac operator at high-temperature, and further support that it belongs to the 3D unitary Anderson model class.

cond-mat.dis-nn↗

arXiv2001

Vortex waistlines and vortex gas

We investigate the manner in which a linear potential arises from fluctuations due to vortices linked with the Wilson loop. In particular, the customary naive picture is critically reexamined.

hep-lat↗

arXiv2000

Vortex structure of the vacuum and confinement

We discuss the recently published numerical computations of the vortex free energy. They dramatically demonstrate that the excitation probability for a sufficiently thick vortex approaches unity at large beta, i.e. that thick vortices `condense' in the vacuum. This is known to imply confinement. An analytical approach for exploring this phenomenon is also outlined.

hep-lat↗

arXiv1999

Vortices and confinement

We review recent developments in the vortex picture of confinement. We discuss numerical simulations demonstrating that the entire asymptotic string tension is due to vortex-induced fluctuations of the Wilson loop. Analytical and numerical results concerning the presence of vortices as the necessary and sufficient condition for confinement at arbitrarily weak coupling in SU(N) gauge theories are also discussed.

hep-lat↗

arXiv1999

Bound on the string tension by the excitation probability for a vortex

A lower bound on the string tension for large beta in SU(2) LGT is derived. The derivation is from first principles and bounds the string tension from below by the expectation for the excitation of a single `tagged' thick vortex winding around the lattice. Thus confinement follows if this expectation remains nonvanishing at large beta. Numerical simulations are presented to show that this is indeed the case.

hep-lat↗

arXiv1998

SU(3) string tension and the presence of vortices

Lattice simulations are presented showing the expectation of the fluctuation of the Wilson loop solely by elements of the center to fully reproduce the SU(3) heavy quark potential. The results are stable under smoothing, and point to thick vortices as being responsible for the full SU(3) tension. An analytic result on the necessary presence of thick vortices for confinement at weak coupling is also presented.

hep-lat↗

arXiv1998

Vortices and the SU(3) string tension

We present simulation results comparing the SU(3) heavy quark potential extracted from the full Wilson loop expectation to that extracted from the expectation of the Wilson loop fluctuation solely by elements of Z(3). The two potentials are found to coincide. This agreement is stable under multiple smoothings of the configurations which remove short distance fluctuations, and thus reflects long-distance physics. It strongly indicates that the asymptotic string tension arises from thick center vortices linking with the Wilson loop.

hep-lat↗

arXiv1998

Absence of confinement in the absence of vortices

We consider the Wilson loop expectation in SU(2) lattice gauge theory in the presence of constraints. The constraints eliminate from the functional measure gauge field configurations whose physical interpretation is that of thick center vortices linking with the loop. We give a simple proof that, for dimension $d \geq 3$, the so constrained Wilson loop follows perimeter law, i.e. non-confining behavior, at weak coupling (low temperature). Thus the presence of vortex configurations is a necessary condition for confinement.

hep-lat↗