Discussion Overview
The discussion revolves around the energy dependence of the Equivalent Photon Approximation (EPA) and its validity at high center of mass energies, specifically questioning its application at 100 TeV. Participants explore the conditions under which the EPA is applicable and the potential limitations or corrections needed for accurate physical descriptions.
Discussion Character
- Exploratory
- Technical explanation
- Debate/contested
Main Points Raised
- One participant inquires about the maximum center of mass energy for the EPA to be valid, specifically asking if it can be applied at 100 TeV.
- Another participant suggests that the validity of the EPA depends on the type of process being considered, such as elastic or inelastic scattering, and emphasizes the role of the probe energy and exchange energy Q².
- A follow-up question is posed regarding the validity of the EPA for the gg->e-e+ process at 100 TeV, indicating a specific application of the approximation.
- One participant expresses skepticism about the EPA being a good approximation at high energies, noting that the cross-section may be influenced by low-Q values, which could lead to significant power corrections that the EPA neglects.
- Concerns are raised about the photon flux distributions potentially peaking at small Q values, which could affect the applicability of the EPA in certain scenarios.
Areas of Agreement / Disagreement
Participants do not reach a consensus on the validity of the EPA at high energies. There are competing views regarding the conditions under which the approximation holds, and the discussion remains unresolved regarding its applicability in specific processes.
Contextual Notes
Participants highlight the dependence of the EPA's validity on various energy scales and the nature of the scattering process, indicating that assumptions about these factors are crucial for determining the approximation's applicability.