The Proton in High Definition: Revisiting Photon-Initiated Production in High Energy Collisions

Understand

We re-examine the current state of the art for the calculation of photon-initiated processes at the LHC, as formulated in terms of a photon PDF in the proton that may be determined rather precisely from the known proton structure functions.

• We in particular demonstrate that a by construction more precise calculation is provided by a direct application of the structure function approach, best known from the case of Higgs Boson production via vector boson fusion.
• This avoids any artificial scale variation uncertainties, which can otherwise be rather significant for processes calculated within the standard approach thus far.
• To understand the source of these, we present a detailed comparison of the structure function approach and its relation to the photon PDF.