Analytic model of Regge trajectories

A model for a Regge trajectory compatible with the threshold behavior requi red by unitarity and asymptotics in agreement with analyticity constraints is given in explicit form. The model is confronted in the time-like region a with widths and masses of the mesonic resonances and, in the space-like r egion, the rho trajectory is compared with predictions derived from the pi -N charge-exchange reaction. Breaking of the exchange degeneracy is studied in the model and its effect on both the masses and widths is determined.