Tantalizing dilaton tests from a near-conformal EFT

Fodor, Zoltán and Holland, K. and Kuti, J. and Wong, C.H. (2018) Tantalizing dilaton tests from a near-conformal EFT. POS - PROCEEDINGS OF SCIENCE, 334. ISSN 1824-8039

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Abstract

The dissociation of quarkonia in the medium created 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 signa- tures 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 descrip- tion [1] 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 contin- ued 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 n f = 8 flavors.

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