Finite-size scaling tests for SU(3) lattice gauge theory with color sextet fermions

The observed slow running of the gauge coupling in SU(3) lattice gauge theory with two flavors of color sextet fermions naturally suggests it is a theory with one relevant coupling, the fermion mass, and that at zero mass correlation functions decay algebraically. I perform a finite-size scaling study on simulation data at two values of the bare gauge coupling with this assumption and observe a common exponent for the scaling of the correlation length with the fermion mass, y_m ~ 1.5. An analysis of the scaling of valence Dirac eigenvalues at one of these bare couplings produces a similar number.Comment: 23 pages, revtex, 13 figure

Lattice studies of QCD-like theories with many fermionic degrees of freedom

I give an elementary introduction to the study of gauge theories coupled to fermions with many degrees of freedom. Besides their intrinsic interest, these theories are candidates for nonperturbative extensions of the Higgs sector of the Standard Model. While related to QCD, these systems can exhibit very different behavior from it: they can possess a running gauge coupling with an infrared attractive fixed point (IRFP). I briefly survey recent lattice work in this area.Comment: 17 pages; report from the INT Workshop "New applications of the renormalization group in nuclear, particle, and condensed matter physics", held February 22-26 201

Improving meson two-point functions in lattice QCD

We describe and test a method to compute Euclidean meson two-point functions in lattice QCD. The contribution from the low-lying eigenmodes of the Dirac operator is averaged over all positions of the quark sources. The contribution from the higher modes is estimated in the traditional way with one or a few source points per lattice. In some channels, we observe a significant improvement in the two-point functions for small quark masses.Comment: 10 pages, 7 figure