TY - JOUR

T1 - Tantalizing dilaton tests from a near-conformal EFT

AU - Fodor, Zoltan

AU - Holland, Kieran

AU - Kuti, Julius

AU - Wong, Chik Him

N1 - Funding Information:
We acknowledge support by the DOE under grant DE-SC0009919, by the NSF under grant 1620845, and by the Deutsche Forschungsgemeinschaft grant SFB-TR 55. Computational resources were provided by the DOE INCITE program on the ALCF BG/Q platform, by USQCD at Fermilab, by the University of Wuppertal, and by the Juelich Supercomputing Center on Juqueen.
Publisher Copyright:
© Copyright owned by the author(s) under the terms of the Creative Commons.

PY - 2018

Y1 - 2018

N2 - 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 [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 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.

AB - 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 [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 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.

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M3 - Conference article

AN - SCOPUS:85069962680

VL - 334

JO - Proceedings of Science

JF - Proceedings of Science

SN - 1824-8039

M1 - 196

T2 - 36th Annual International Symposium on Lattice Field Theory, LATTICE 2018

Y2 - 22 July 2018 through 28 July 2018

ER -