Excited Hadrons and Quark-Hadron Duality

We review how Quark-Hadron Duality (QHD) for (u,d) flavors at high energies and in the scaling regime suggests a radial and angular behaviour of mesonic and baryonic resonance masses of the Regge form $M^2_{nJ} = \mu^2 n + \beta^2 J

• M_0^2 $. The radial mass dependence is asymptotically consistent with a common two-body dynamics for mesons and baryons in terms of the quark-antiquark ($q\bar{q})$ and quark-diquark ($qD$) degrees of freedom, respectively. This formula is validated phenomenologically within an uncertainty determined by half the width of the resonances, $\mathrm{\Delta }{M}_{nJ}^2\sim {\mathrm{\Gamma }}_{nJ}{M}_{nJ}$. With this error prescription we find from the non-strange PDG hadrons different radial slopes ${\mu }_{\bar{q}q}^2=1.34(4){\mathrm{G}\mathrm{e}\mathrm{V}}^2$ and $\mu^2_{qD}=0.75(3) {\rm GeV}^2$,butsimilarangularslopes$\beta_{\bar q q}^2 \sim \beta_{ q D}^2 \sim 1.15 {\rm GeV}^2$.