Hadronic spectrum in the chiral large Nc extension of quantum chromodynamics

Abstract

We study quantum chromodynamics in the chiral large Nc limit which contains a left-handed Weyl fermion in the fundamental representation, a left-handed Weyl fermion in the two index antisymmetric representation and (Nc−3) left-handed Weyl fermions in the antifundamental representation of the SU(Nc) gauge group. We construct gauge singlet composite operators and study their masses and correlation functions at large Nc. It is shown that all hadron masses scale as ∼Nc0nq where nq is the number of constituent quarks in the hadron. In addition by simple gluon exchange considerations it is seen that scattering amplitudes between hadrons have the same Nc scaling as the mass of the lightest hadron involved. This is the case provided the hadrons in the scattering amplitude share a sufficiently large number of constituent quarks. The chiral large Nc extension also allows for other nontrivial processes. For instance we consider two different baryonium states that are unique to this extension and that decay via emissions of two- and three-quark hadrons. Also other nontrivial scattering processes are considered. Finally, we study composites made of a mix of left- and right-handed fields. We categorize multiple groups of hadrons within the full spectrum according to their flavor structure. Within these groups all n-point functions scale the same. Published by the American Physical Society 2024