Improved Parton Distributions from the Quark Model

Abstract

There has recently been significant progress in the calculation of the twist-two piece of the quark/parton distributions corresponding to models like the MIT bag. However, in evaluating the required matrix elements of the quark field operators Signal and Thomas (1988, 1989) resorted to the Peierls-Yoccoz (1957) approximation-albeit with some cautionary remarks. We point out a problem with that approach which is solved by using the Peierls-Thouless (1962) approximation for the hadronic states. The very simple case of a nonrelativistic constant density quark wavefunction is solved in detail.