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The leading $1/N_c$ behaviour of Unitarised Chiral Perturbation Theorydistinguishes the nature of the $\rho$ and the $\sigma$. At one loop order the$\rho$ is a ${\bar q}q$ meson, while the $\sigma$ is not. However, semi-localduality between resonances and Regge behaviour cannot be satisfied for larger$N_c$, if such a distinction holds. While the $\sigma$ at $N_c=3$ is inevitablydominated by its di-pion component, Unitarised Chiral Perturbation Theorybeyond one loop order reveals that as $N_c$ increases above 6-8, the $\sigma$has a sub-dominant ${\bar q}q$ fraction up at 1.2 GeV. Remarkably this ensuressemi-local duality is fulfilled for the range of $N_c \lesssim 15$, where theunitarisation procedure adopted applies.

Chiral Perturbation Theory, the ${1/N_c}$ expansion and Regge behaviour determine the structure of the lightest scalar meson