Are hadrons simpler than they seem?

TL;DR

This paper reviews a systematic approximation scheme of QCD where hadrons are described using a linear potential derived from boundary conditions, leading to a quark model picture that includes relativistic states and sea quarks.

Contribution

It introduces a novel approximation scheme of QCD that naturally produces a linear potential and incorporates relativistic effects with sea quarks using valence wave functions.

Findings

Linear A^0 potential arises from boundary conditions in QCD.

Relativistic states with sea quarks can be described using valence wave functions.

Perturbative corrections can be computed with bound states instead of plane waves.

Abstract

I briefly review a systematic approximation scheme of QCD in which the quark model picture of hadrons emerges at lowest order. A linear A^0 potential arises if Gauss' law is solved with a non-vanishing boundary condition at spatial infinity. Similarly to the Dirac case one can describe relativistic states including any number of particle pairs (sea quarks) using valence wave functions, whose norms give {\em inclusive} probability densities. Provided \alpha_s(Q^2) freezes in the infrared, perturbative corrections to the S-matrix can be calculated in the usual way, but with states bound by the linear \order{\alpha_s^0} potential instead of plane waves in the in and out states.