Constituent Counting Rules and Exotic Hadrons

TL;DR

This paper explores how constituent counting rules can be used to identify exotic hadrons like pentaquarks and tetraquarks through their unique scaling behaviors in high-energy exclusive processes, supported by AdS/QCD calculations.

Contribution

It demonstrates the application of constituent counting rules to detect exotic multiquark states and introduces new scaling behaviors in forward scattering, with explicit AdS/QCD computations.

Findings

Scaling behaviors can indicate exotic multiquark content.

New Mandelstam s and t scaling in forward scattering.

AdS/QCD provides explicit amplitude calculations.

Abstract

The constituent counting rules, i.e., the scaling behavior of amplitudes (in terms of the number of fundamental constituents) for exclusive processes when high energy scales are present, have been known for decades, and have been borne out in a number of experiments. Such scaling would be sensitive, in particular, to possible exotic multiquark content. Here we examine how one may use the rules to test for pentaquarks in electroproduction, or for tetraquarks in e^+ e^- annihilation. An interesting new type of scaling (separate Mandelstam s and t behavior) arises in the forward scattering direction. The correct scaling arises naturally in AdS/QCD, in which the amplitudes can be computed explicitly.