6533b7d0fe1ef96bd125a186

RESEARCH PRODUCT

Large-NCproperties of theρandf0(600)mesons from unitary resonance chiral dynamics

subject

description

We construct $\ensuremath{\pi}\ensuremath{\pi}$ amplitudes that fulfill exact elastic unitarity, account for one-loop chiral perturbation theory contributions and include all $1/{N}_{C}$ leading terms, with the only limitation of considering just the lowest-lying nonet of exchanged resonances. Within such a scheme, the ${N}_{C}$ dependence of $\ensuremath{\sigma}$ and $\ensuremath{\rho}$ masses and widths is discussed. Robust conclusions are drawn in the case of the $\ensuremath{\rho}$ resonance, confirming that it is a stable meson in the limit of a large number of QCD colors, ${N}_{C}$. Less definitive conclusions are reached in the scalar-isoscalar sector. With the present quality of data, we cannot firmly conclude whether or not the ${N}_{C}=3$ ${f}_{0}(600)$ resonance completely disappears at large ${N}_{C}$ or if it has a subdominant component in its structure, which would become dominant for a number of quark colors sufficiently large.