Unintegrated parton distributions and prompt photon hadroproduction
M.A. Kimber1 - A.D. Martin1 - M.G. Ryskin1,2
1 Department of Physics, University of Durham, Durham, DH1 3LE
2 Petersburg Nuclear Physics Institute, Gatchina, St. Petersburg, 188350, Russia
Received: 18 November 1999 / Published online: 27 January 2000 - © Springer-Verlag 2000 2000
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 qt of the incoming partonic system on the calculation of the transverse momentum spectra of prompt photons produced in high energy pp and collisions. For the purposes of illustration, we use the double logarithm approximation. For large qt we calculate the effect directly from the perturbative formalism, whereas for small qt we bound the effect using two extreme hypotheses. In both qt domains we find that the shapes of the prompt photon spectra are not significantly modified, although the cross sections are enhanced.
Copyright Springer-Verlag 2000