Photoproduction of dileptons and photons in p-p collisions at Large Hadron Collider energies

TL;DR

This paper calculates the production of high transverse momentum dileptons and photons in proton-proton collisions at LHC energies, comparing exact methods with the equivalent photon approximation, and highlights the limitations of the approximation.

Contribution

It introduces an exact calculation method for photoproduction processes in p-p collisions, improving accuracy over the equivalent photon approximation especially at high virtuality.

Findings

Equivalent photon approximation is effective only at small Q^2.

Proper Q^2_max choice is crucial for accurate coherent photoproduction.

Exact treatment is necessary for large p_T dilepton and photon production.

Abstract

The production of large $p_{T}$ dileptons and photons originating from photoproduction processes in p-p collisions at Large Hadron Collider energies is calculated. The comparisons between the exact treatment results and the ones of the equivalent photon approximation approach are expressed as the $Q^{2}$ (the virtuality of photon) and $p_{T}$ distributions. The method developed by Martin and Ryskin is used for avoiding double counting when the coherent and incoherent contributions are considered simultaneously. The numerical results indicate that, the equivalent photon approximation is only effective in small $Q^{2}$ region and can be used for coherent photoproduction processes with proper choice of $Q^{2}_{\textrm{max}}$ ( the choices $Q^{2}_{\textrm{max}}\sim \hat{s}$ or $\infty$ will cause obvious errors), but can not be used for incoherent photoproduction processes. The exact treatment is needed to deal accurately with the photoproduction of large $p_{T}$ dileptons and photons.