Infrared dynamics of minimal walking technicolor

Abstract

We study the gauge sector of Minimal Walking Technicolor, which is an SU(2) gauge theory with n f = 2 flavors of Wilson fermions in the adjoint representation. Numerical simulations are performed on lattices Nt × N 3 s , with Ns ranging from 8 to 16 and Nt = 2Ns, at fixed β = 2.25, and varying the fermion bare mass m0, so that our numerical results cover the full range of fermion masses from the quenched region to the chiral limit. We present results for the string tension and the glueball spectrum. A comparison of mesonic and gluonic observables leads to the conclusion that the infrared dynamics is given by an SU(2) pure Yang-Mills theory with a typical energy scale for the spectrum sliding to zero with the fermion mass. The typical mesonic mass scale is proportional to, and much larger than this gluonic scale. Our findings are compatible with a scenario in which the massless theory is conformal in the infrared. An analysis of the scaling of the string tension with the fermion mass towards the massless limit allows us to extract the chiral condensate anomalous dimension γ * , which is found to be γ * = 0.22 ± 0.06.

Large mass hierarchies from strongly-coupled dynamics

“…We will show, also by comparison with our toy model, that this procedure depends on the precise way the different limits are taken. We are also interested to see whether the ratio R obtained in this way contains non-trivial information about the anomalous dimensions, generalising [35].…”

Lattice studies of quantum chromodynamics-like theories with many fermionic degrees of freedom

“…Then, the mass is the relevant perturbation and all the statistical mechanics machinery for scaling near a critical point can be employed. This gives g m (g 2 ) for SU (2) in a wide variety of ways [51][52][53]. It turns out to be small, less than about 0.5, and consistent with perturbation theory, equation (1.6).…”

“…Many groups (a representative list includes [48][49][50][51][52][53]) have studied N f = 2 flavours of adjoint representation fermions in SU (2). All studies to date use Wilson-type quarks.…”

Conformal finite size scaling of twelve fermion flavors

“…The scaling form sets in close to the critical surface for small m values. The scaling functions f (x) can depend on the quantum numbers of the states but the scaling variable is expected to have the same form with identical γ exponent in each quantum number channel [15][16][17][18][19]. In sub-leading order there are conformal FSS scaling violation effects which are exhibited as a combined cutoff and L-dependent leading correction with the modified form…”