Light- and strange-quark mass dependence of the $\rho(770)$ meson properties

TL;DR

This study analyzes how the properties of the rho meson depend on light and strange quark masses using lattice QCD data, predicting mass variations and coupling ratios along different chiral trajectories.

Contribution

It provides the first detailed analysis of rho meson properties across different quark mass trajectories, including predictions for lighter strange quark masses.

Findings

Rho meson mass can be as low as 700 MeV at zero strange quark mass.

Coupling ratio to $\pi\pi$ and $Kar{K}$ channels is $\sqrt{2}$ at SU(3) symmetry.

Mass dependence predictions extend to lighter-than-physical strange quark masses.

Abstract

From an analysis of recent ($I=J=1$)-$\pi\pi$-phase-shift and pseudoscalar-meson decay-constant lattice data on two distinct chiral trajectories, where either the sum of the up, down and strange quark masses, or the mass of the strange quark is kept fixed, we extract the light and strange quark mass dependence of the rho meson parameters, and make predictions of those on chiral trajectories which involve lighter masses than the physical strange quark mass. We find that the mass of the rho meson can get as light as $700$ MeV for strange quark mass zero at physical pion masses. While the ratio of the couplings to the $\pi\pi$ and $K\bar{K}$ channels is equal to $\sqrt{2}$ at the SU(3) symmetric chiral trajectory.