Unintegrated parton distributions and prompt photon hadroproduction

TL;DR

This paper develops a method to derive unintegrated parton distributions from standard ones and studies how the transverse momentum of incoming partons affects prompt photon production spectra in high-energy collisions, finding shape stability but cross section enhancement.

Contribution

It introduces a general formalism to obtain unintegrated parton distributions from conventional densities and applies it to analyze prompt photon spectra in high-energy collisions.

Findings

Prompt photon spectra shapes are not significantly altered by transverse momentum effects.

Cross sections for prompt photon production are enhanced due to transverse momentum effects.

The formalism provides a way to incorporate parton transverse momentum into existing parton distribution functions.

Abstract

We introduce a general expression which enables the parton distribution, unintegrated over the parton transverse momentum, to be obtained from the conventional parton densities. We use the formalism to study the effects of the transverse momentum q_t of the incoming partonic system on the calculation of the transverse momentum spectra of prompt photons produced in high energy pp and p\bar{p} collisions. For the purposes of illustration, we use the double logarithm approximation. For large q_t we calculate the effect directly from the perturbative formalism, whereas for small q_t we bound the effect using two extreme hypotheses. In both q_t domains we find that the shapes of the prompt photon spectra are not significantly modified, although the cross sections are enhanced.