Strange and nonstrange quark mass dependence of elastic light resonances from SU(3) unitarized chiral perturbation theory to one loop

Abstract

We study the light quark mass dependence of the f _0(600), к(800), ρ(770), and K*(892) resonance parameters generated from elastic meson-meson scattering using unitarized one-loop chiral perturbation theory. First, we show that it is possible to 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 400 MeV, using chiral parameters compatible with existing determinations. Then, the strange and nonstrange 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 ρ(770) and K*(892) present a similar and smooth quark mass dependence. In contrast, both scalars present a similar nonanalyticity at high quark masses. Nevertheless, the f_0(600) dependence on the nonstrange quark mass is stronger than for the к(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. As a consequence, vector widths are very well approximated by the Kawarabayashi-Suzuki-Riazuddin- Fayyazuddin relation, and their masses are shown to scale like their corresponding meson decay constants.