Trouble in Asymptopia---the Hulthen Model on the Light Front

Abstract

We use light-front dynamics to calculate the electromagnetic form-factor for the Hulthen model of the deuteron. For small momentum transfer Q^2 < 5 GeV^2 the relativistic effects are quite small. For Q^2 = 11 GeV^2 there is about a 13% discrepancy between the relativistic and non-relativistic approaches. For asymptotically large momentum transfer, however, the light-front form factor, log Q^2 /Q^4, markedly differs from the non-relativistic version, 1/Q^4. This behavior is also present for any wave function, such as those obtained from realistic potential models, which can be represented as a sum of Yukawa functions. Furthermore, the asymptotic behavior is in disagreement with the Drell-Yan-West relation. We investigate precisely how to determine the asymptotic behavior and confront the problem underlying troublesome form factors on the light front.