QCD with colour-sextet quarks

Abstract

We study QCD with 2 colour-sextet quarks as a model for walking Technicolor, using lattice gauge theory simulations (RHMC) at finite temperature. Our goal is to determine if the massless theory is QCD-like (confining, with spontaneously-broken chiral symmetry) with a slowly varying coupling (walks) or if it is a conformal field theory. We do this by simulating the theory at finite temperature and observing how the coupling at the chiral-symmetry restoration temperature depends on the temporal extent $N_t$ of the lattice (in lattice units). If the theory is QCD-like, this coupling should approach zero in the large $N_t$ limit in the manner predicted by asymptotic freedom. If it is conformal, this coupling should approach a finite value in this limit, i.e. the transition would be a bulk transition. We discuss new results at $N_t=6,8$ and 12. These preliminary results indicate that the coupling does decrease with increasing $N_t$, but it is unclear if this is consistent with asymptotic freedom.

7 pages Latex 4 postscript figures. Talk presented by D. K. Sinclair at Lattice 2012, Cairns, Australia

References in corpus (4)

• Zero of the discrete beta function in SU(3) lattice gauge theory with color sextet fermions
• Phase structure of SU(3) gauge theory with two flavors of symmetric-representation fermions
• Parity Doubling and the S Parameter Below the Conformal Window
• Chiral symmetry breaking in fundamental and sextet fermion representations of SU(3) color