Light-Cone Wavefunctions at Small $x$

Abstract

There exist an infinite number of exact small momentum fraction-$x$ boundary conditions on light-cone wavefunctions of bound states in gauge theory. They are necessary for finite expectation values of the invariant mass operator and relate components of the wavefunction from different Fock sectors. We illustrate their consequences by analyzing the small-$x$ quark Regge behavior of a heavy large-$N$ meson, finding power-law rise of unpolarized distributions. The polarized distribution changes sign and then vanishes with minus the unpolarized Regge intercept.