Benjamin Svetitsky

Zero of the discrete beta function in SU(3) lattice gauge theory with color sextet fermions

We have carried out a Schrodinger functional calculation for the SU(3) lattice gauge theory with two flavors of Wilson fermions in the sextet representation of the gauge group. We find that the discrete beta function, which governs the change in the running coupling under a discrete change of spatial scale, changes sign when the Schrodinger functional renormalized coupling is in the neighborhood of g{sup 2}=2.0. The simplest explanation is that the theory has an infrared-attractive fixed point, but more complicated possibilities are allowed by the data. While we compare rescalings by factors of 2 and 4/3, we work at a single lattice spacing.

Phase structure of SU(3) gauge theory with two flavors of symmetric-representation fermions

We have performed numerical simulations of SU(3) gauge theory coupled to

Running coupling and mass anomalous dimension of SU(3) gauge theory with two flavors of symmetric-representation fermions

{N}_{f}=2

Particle production in the central rapidity region

flavors of symmetric-representation fermions. The fermions are discretized with the tadpole-improved clover action. Our simulations are done on lattices of length

Mass anomalous dimension in sextet QCD

L=6

Breakdown of staggered fermions at nonzero chemical potential

, 8, and 12. In all simulation volumes we observe a crossover from a strongly coupled confined phase to a weak-coupling deconfined phase. Degeneracies in screening masses, plus the behavior of the pseudoscalar decay constant, indicate that the deconfined phase is also a phase in which chiral symmetry is restored. The movement of the confinement transition as the volume is changed is consistent with avoidance of the basin of attraction of an infrared fixed point of the massless theory.

Localization properties of lattice fermions with plaquette and improved gauge actions

We have measured the running coupling constant of SU(3) gauge theory coupled to N{sub f}=2 flavors of symmetric representation fermions, using the Schroedinger functional scheme. Our lattice action is defined with hypercubic smeared links which, along with the larger lattice sizes, bring us closer to the continuum limit than in our previous study. We observe that the coupling runs more slowly than predicted by asymptotic freedom, but we are unable to observe fixed point behavior before encountering a first order transition to a strong coupling phase. This indicates that the infrared fixed point found with the thin-link action is a lattice artifact. The slow running of the gauge coupling permits an accurate determination of the mass anomalous dimension for this theory, which we observe to be small, {gamma}{sub m} < or approx. 0.6, over the range of couplings we can reach. We also study the bulk and finite-temperature phase transitions in the strong coupling region.

Extracting F π from small lattices: Unquenched results

We study pair production from a strong electric field in boost-invariant coordinates as a simple model for the central rapidity region of a heavy-ion collision. We derive and solve the renormalized equations for the time evolution of the mean electric field and current of the produced particles, when the field is taken to be a function only of the fluid proper time

Nonperturbative infrared fixed point in sextet QCD

\ensuremath{\tau}=\sqrt{{t}^{2}\ensuremath{-}{z}^{2}}

Exploring the phase diagram of sextet QCD

. We find that a relativistic transport theory with a Schwinger source term modified to take Pauli blocking (or Bose enhancement) into account gives a good description of the numerical solution to the field equations. We also compute the renormalized energy-momentum tensor of the produced particles and compare the effective pressure, energy, and entropy density to that expected from hydrodynamic models of energy and momentum flow of the plasma.