The forward slope in photoproduction and electroproduction of ϱ0

Abstract

The t-dalaegde~ee of these amplitudes is of the form is a function which has the same gross behavior as Jaa (a Bessel function of order A2). The exact functional form of <~ Jsx ,) depends on the finer details of the impact-parameter profile. I t has become a common practice to parameterize <~ JAz )) in the form exp[Bt] JAa(R ~/~~t), where 2 ~/B is the width a of the impact-parameter profile. This choice seems to yield a nice description of experimental data (2.3). The diffractive amplitudes are assumed to be central in the b-space, and to have no structure (zeros, dips, etc.) as functions of t. These amplitudes are assumed to be mainly nonfiip, and mainly pure imaginary, and therefore parameterized by i exp [B~t]. In this note we wish to apply the dual-absorptive model to the process y p ~ pop near the forward direction. The exact values of the forward differential cross-section (d~/dt)0 and of the forward slope S vary from one experimental group to another, and also depend on the method of the analysis in which the p0 is extracted (4). There are