Limits on the diffractive mass in strong coherent $\gamma^*$-nucleus scattering

TL;DR

This paper derives an evolution equation for diffractive production in coherent gamma*-nucleus scattering, showing that in the saturation regime, the diffractive mass remains close to the virtuality Q, with larger masses suppressed.

Contribution

It introduces a new evolution equation for diffractive production with a rapidity gap and analyzes the behavior of diffractive masses in the saturation region.

Findings

Diffractive mass is on the order of the virtuality Q in strong scattering.

Large diffractive masses are suppressed by the Levin-Tuchin mechanism.

Diffractive production is constrained by unitarity in the saturation regime.

Abstract

An evolution equation for diffractive production with a definite rapidity gap is given. Coherent $\gamma^*A$ collisions in the unitarity (saturation) region are studied with the conclusion that the diffractive mass is always on the order of the $\gamma^*$ virtuality, $Q$, when the scattering is strong. Deep in the saturation region diffractive masses significantly greater than $Q$ are strongly suppressed by a Levin-Tuchin mechanism.