Heterotic Approach to the Nucleon Distribution Amplitude

We give an in-depth analysis of the determination procedure of the recently proposed heterotic nucleon distribution amplitude which hybridizes the best features of the Chernyak-Ogloblin-Zhitnitsky and the Gari-Stefanis models. With respect to the QCD sum-rule constraints, optimized versions of these amplitudes are derived in terms of which a ”hybridity” angle can be introduced to systematically classify all models. Typeset using REVTEX E-mail: [email protected] Work supported in part by the Deutsche Forschungsgemeinschaft 1 Large-momentum transfer exclusive reactions comprise two mechanisms based on the factorization theorem [1,2]: the hard-gluon exchanges that describe short-range interactions via perturbation theory and the long-range (nonperturbative) soft processes that ensure confinement in the hadronic states. Thus, such processes depend in detail on the composition of the hadron wave function or more precisely, the hadron distribution amplitude: Φ(xi, Q ). In a physical gauge as the light-cone gauge A = A + A = 0, this is the fundamental covariant amplitude describing the correlations between massless valence quarks with fractional momenta 0 ≤ xi = k i p+ ≤ 1 ( ∑ i xi = 1) and relative transverse momenta k (i) ⊥ , p + being the longitudinal momentum of the incoming hadron. Then, apart from logarithmic scaling violations, Φ(xi, Q ) = ∫ Q2 [dk⊥]ψ(xi,k (i) ⊥ ), (1) where [dk⊥] = 16π δ( ∑3 i=1 k (i) ⊥ ) ∏3 i=1 [