Extent of sensitivity of single photon production to parton distribution functions

TL;DR

This study investigates how different parton distribution functions affect the predicted production of single prompt photons in high-energy proton-proton collisions at RHIC and LHC energies, finding minimal variation within experimental errors.

Contribution

It compares multiple modern PDFs in perturbative QCD calculations of prompt photon production and assesses their impact on theoretical predictions against experimental data.

Findings

Prompt photon cross-sections are well described by all PDFs within errors.

Differences between PDFs are within ±20% of CTEQ4M.

Diphoton measurements could help constrain the gluon distribution.

Abstract

We have studied the production of single isolated prompt photons in high energy proton-proton collisions at the RHIC ($\sqrt{s}$= 200 GeV) and the LHC ($\sqrt{s}$= 7 TeV) energies within the frame work of perturbative QCD upto next-to leading order of strong coupling ($\alpha_s$). We have used five different parameterizations of parton distribution function (PDF) starting from the old CTEQ4M to the new CT10 distributions and compared our results with the recent single prompt photon data from the PHENIX and the CMS collaborations. The prompt photon cross-section is found to be described equally well by all the PDF's within the experimental errors at the RHIC and the LHC energies. The deviation in the prompt photon yield for different PDF sets is within $\pm$ 20% when compared to CTEQ4M. The diphoton measurement could be a potential candidate to constrain the gluon distribution inside the proton.