Speaker
Description
The Good-Walker paradigm is widely used for studying ultra-peripheral collisions (UPCs) and underlies much of the exclusive photoproduction/electroproduction program at the future electron-ion collider (EIC). It relates the cross-section for coherent photoproduction, $d\sigma/dt$ to the transverse distribution of scattering centers in a target, and ties the incoherent cross-section to fluctuations of the target configuration, including gluonic hotspots. In this talk, I will present examples where the Good-Walker approach clearly fails, and compare the predictions with a semi-classical approach. I will explain why it fails, and show that the problem is general, including both UPCs and an EIC. I will discuss some possible expansions that will allow it to work in UPCs and at an EIC.
| Submitted on behalf of a Collaboration? | No |
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