Chiral-scale perturbation theory χPTσ has been proposed as an
alternative to chiral SU(3)L×SU(3)R perturbation theory which
explains the ΔI=1/2 rule for kaon decays. It is based on a low-energy
expansion about an infrared fixed point in three-flavor QCD. In
χPTσ, quark condensation ⟨qˉq⟩vac=0 induces nine Nambu-Goldstone bosons: π,K,η and a QCD dilaton
σ which we identify with the f0(500) resonance. Partial conservation
of the dilatation and chiral currents constrains low-energy constants which
enter the effective Lagrangian of χPTσ. These constraints allow us
to obtain new phenomenological bounds on the dilaton decay constant via the
coupling of σ/f0 to pions, whose value is known precisely from
dispersive analyses of ππ scattering. Improved predictions for σ→γγ and the σNN coupling are also noted. To test
χPTσ for kaon decays, we revive a 1985 proposal for lattice
methods to be applied to K→π on-shell.Comment: 10 pages, 1 figure. Presented at the 8th International Workshop on
Chiral Dynamics, 29 June 2015 - 03 July 2015, Pisa, Italy. Revision:
references and comment adde