Hidden conformal symmetry from the lattice
Thomas Appelquist, Richard C. Brower, K. K. Cushman, George Fleming, Andrew Gasbarro, Anna Hasenfratz, James Ingoldby, Xiao-Yong Jin, Ethan T. Neil, James C. Osborn, C. Rebbi, Enrico Rinaldi, David Schaich, Pavlos Vranas, Evan Weinberg, Oliver Witzel
Abstract
We analyze newly expanded and refined data from lattice studies of an $SU(3)$ gauge theory with eight Dirac fermions in the fundamental representation. We focus on the light composite states emerging from these studies, consisting of a set of pseudoscalars and a single light scalar. We first consider the view that this theory is just outside the conformal window. In this case, the pseudoscalars arise from spontaneous breaking of chiral symmetry. Identifying the scalar in this case as an approximate dilaton, we fit the lattice data to a dilaton effective field theory, finding that it yields a good fit even at lowest order. For comparison, we then consider the possibility that the theory is inside the conformal window. The fermion mass provides a deformation, triggering confinement. We employ simple scaling laws to fit the lattice data and find that it is of lesser quality.