The dilaton low-energy effective field theory (EFT) of an emergent light scalar is probed in the paradigm of strongly coupled near-conformal gauge theories. These studies are motivated by models which exhibit small β-functions near the conformal window (CW), perhaps with slow scale-dependent walking and a light scalar with 0++ quantum numbers. We report our results from the hypothesis of a dilaton inspired EFT analysis with two massless fermions in the two-index symmetric (sextet) representation of the SU(3) color gauge group. With important caveats in our conclusions, conformal symmetry breaking entangled with chiral symmetry breaking would drive the near-conformal infrared behavior of the theory predicting characteristic dilaton signatures of the light scalar from broken scale invariance when probed on relevant scales of fermion mass deformations. From a recently reasoned choice of the dilaton potential in the EFT description  we find an unexpectedly light dilaton mass in the chiral limit at md/fπ = 1.56(28), set in units of the pion decay constant fπ. Subject to further statistical and systematic tests of continued post-conference analysis, this result is significantly lower than our earlier estimates from less controlled extrapolations of the light scalar (the σ-particle) to the massless fermion limit of chiral perturbation theory. We also discuss important distinctions between the dilaton EFT analysis and the linear σ-model without dilaton signatures. For comparative reasons, we comment on dilaton tests from recent work with fermions in the fundamental representation with nf = 8 flavors.
|Proceedings of Science
|Published - 2018
|36th Annual International Symposium on Lattice Field Theory, LATTICE 2018 - East Lansing, United States
Duration: Jul 22 2018 → Jul 28 2018
All Science Journal Classification (ASJC) codes