f_0(600), kappa(800), rho(770) and K*(892), quark mass dependence from unitarized SU(3) Chiral Perturbation Theory

TL;DR

This study investigates how the masses and widths of certain meson resonances depend on quark masses using unitarized SU(3) Chiral Perturbation Theory, fitting experimental and lattice data to reveal non-analytic behaviors and coupling properties.

Contribution

It provides a detailed analysis of quark mass dependence of meson resonances, confirming lattice assumptions and highlighting differences between scalar and vector mesons.

Findings

Rho(770) and K*(892) masses and widths vary smoothly with quark mass.

Scalar mesons like f_0(600) show stronger and non-analytic quark mass dependence.

Vector meson couplings are quark mass independent, scalars are not.

Abstract

We study the strange and non-strange quark mass dependence of the parameters of the f_0(600), kappa(800), rho(770) and K*(892) resonances generated from elastic meson-meson scattering using unitarized one-loop Chiral Perturbation Theory. We fit simultaneously all experimental scattering data up to 0.8-1 GeV together with lattice results on decay constants and scattering lengths up to a pion mass of 440 MeV. Then, the strange and non-strange quark masses are varied from the chiral limit up to values of interest for lattice studies. In these amplitudes, the mass and width of the rho(770) and K*(892) present a similar and smooth quark mass dependence. In contrast, both scalars present a similar non-analyticity at high quark masses. Nevertheless the f_0(600) dependence on both quark masses is stronger than for the kappa(800) and the vectors. We also confirm the lattice assumption of quark mass independence of the vector two-meson coupling that, in contrast, is violated for scalars.