Details

Autor(en) / Beteiligte

• Gasbarro, Andrew
• Pena Ruano, C.
• Gámiz Sánchez, E.
• Della Morte, M.
• Fritzsch, P.

Titel

Can a Linear Sigma Model Describe Walking Gauge Theories at Low Energies?

Ist Teil von

• EPJ Web of Conferences, 2018-01, Vol.175, p.8024

Ort / Verlag

Les Ulis: EDP Sciences

Erscheinungsjahr

2018

Link zum Volltext

Quelle

EZB Electronic Journals Library

Beschreibungen/Notizen

• In recent years, many investigations of confining Yang Mills gauge theories near the edge of the conformal window have been carried out using lattice techniques. These studies have revealed that the spectrum of hadrons in nearly conformal ("walking") gauge theories differs significantly from the QCD spectrum. In particular, a light singlet scalar appears in the spectrum which is nearly degenerate with the PNGBs at the lightest currently accessible quark masses. This state is a viable candidate for a composite Higgs boson. Presently, an acceptable effective field theory (EFT) description of the light states in walking theories has not been established. Such an EFT would be useful for performing chiral extrapolations of lattice data and for serving as a bridge between lattice calculations and phenomenology. It has been shown that the chiral Lagrangian fails to describe the IR dynamics of a theory near the edge of the conformal window. Here we assess a linear sigma model as an alternate EFT description by performing explicit chiral fits to lattice data. In a combined fit to the Goldstone (pion) mass and decay constant, a tree level linear sigma model has a Χ 2 /d.o.f. = 0.5 compared to Χ 2 /d.o.f. = 29.6 from fitting nextto-leading order chiral perturbation theory. When the 0++ (σ) mass is included in the fit, Χ 2 /d.o.f. = 4.9. We remark on future directions for providing better fits to the σ mass.