Parity doubling from Weinberg sum rules

Original · EN

We investigate the relation among slopes and intercepts of Regge trajectories for mesons of a given spin and different parities using large Nc arguments and the matching to perturbative QCD in the deep-Minkowski region. For spin-1 mesons of opposite parities we prove that: a) for large and increasing Nc, the scale Λ⁽ᵛ,ᵃ⁾ separating the resonance-dominated and the perturbative-saturated region in the channels V,A grows as √Nc; b) to satisfy the Weinberg sum rules the slopes of Regge trajectories for mesons of opposite parities must coincide; c) their intercepts may differ and their difference corresponds to the difference between Λᵛ and Λᵃ. Some arguments indicate that this difference should tend to zero as Nc→∞.