Hadronic masses and Regge trajectories

A comprehensive phenomenological analysis of experimental data and some theoretical models is presented here (for mesons) to critically discuss how Regge trajectory parameters depend on flavor. Through the analytic continuation of physical trajectories (obtained from resonance data) into the spacelike region, we derive the suppression factor for heavy flavor production. The case of our $D$ Regge exchange, for both $D$ and ${\Lambda }_c$ production, is considered in some detail. Good agreement with data is reached, confirming that indeed the slopes of heavier flavors decrease. This result suggests that the confinement potential has a substantial dependence on the quark masses. In a simple nonrelativistic model, constrained to produce linear Regge trajectories, it is shown that a linear quark mass dependence is required (in the confinement part of the potential) in order for the slope to decrease in the appropriate way.