Towards a Nonperturbative Foundation of the Dipole Picture: I. Functional Methods

摘要

This is the first of two papers in which we study real and virtualphoton-proton scattering in a nonperturbative framework. We classify differentcontributions to this process and identify the leading contributions at highenergies. We then study the renormalisation of the photon-quark-antiquarkvertex that occurs in the leading contributions. We find something like thedipole picture in one of these contributions but also find two correction termswhich can potentially become large at small photon virtualities. In the secondpaper we will discuss the additional approximations and assumptions that arenecessary to obtain the dipole model of high energy scattering from the resultsfound here.