Regge spectral generator and form factors from hard exclusive amplitudes in holographic QCD

Abstract

We show that the infinite tower of hard exclusive amplitudes in holographic light-front QCD leads to a spectral generator $G(\alpha ,\lambda )$ which encodes the full Regge spectrum. The construction assumes a Poisson distribution of Fock-state components, where $\lambda$ represents the average parton multiplicity above the valence configuration. The resulting generator yields a Regge spectrum invariant under continuous $\lambda$-deformations. Its even- and odd-twist projections yield the meson and baryon form factors with a single value of $\lambda$, fixed by the pion charge radius, which in turn determines the full $Q^2$ dependence. The constituent counting rules for both sectors follow from the structure of the spectral generator, which also provides a compact analytic representation of parton distributions.

Comments: Updated version accepted for publication in Physical Review Letters. Specific couplings to mesons and baryons follow from the even and odd projections of the spectral generator, updated references, 15 pages, 1 figure