Access to Photon Fragmentation Functions in Hadronic Jet Production

TL;DR

This paper proposes using the process $pp o (jet \, \gamma)X$ to probe photon fragmentation functions, providing next-to-leading-order QCD calculations and analyzing background suppression for potential measurements at LHC and RHIC.

Contribution

It introduces a new method to access photon fragmentation functions through jet-photon production in proton-proton collisions with detailed NLO calculations.

Findings

The process offers a clean probe of photon fragmentation functions.

Background from neutral pion decay can be suppressed.

Numerical results suggest feasibility at LHC and RHIC.

Abstract

We argue that the process $pp \to (\text{jet} \gamma)X$, for which a photon is observed inside a fully reconstructed jet and is treated as part of the jet, offers new probes of the so far little known fragmentation functions for photons. We present a next-to-leading-order QCD calculation of the cross section for this process in the limit that the jet is relatively narrow. We also investigate the background resulting from the two-photon decay of neutral pions. We present numerical results relevant for possible measurements at the LHC and at RHIC. These suggest that $pp \to (\text{jet} \gamma)X$ should provide clean access to the photon fragmentation functions, provided an efficient suppression of the background is available in experiment.