M. Fontannaz

Cross section of isolated prompt photons in hadron-hadron collisions

We consider the production of isolated prompt photons in hadronic collisions. We present a general discussion in QCD perturbation theory of the isolation criterion used by hadron collider experiments. The isolation criterion is implemented in a computer programme of the Monte Carlo type, which evaluates the production cross section at next-to-leading order accuracy in perturbative QCD. The calculation includes both the direct and the fragmentation components of the cross section, without any approximation of the dependence on the radius R of the isolation cone. We examine the scale dependence of the isolated cross section, the sensitivity of the cross section to the values of the isolation parameters, and we provide a quantitative comparison between the full R dependence and its small-R approximation.

Recent critical study of photon production in hadronic collisions

In the light of the new prompt-photon data collected by PHENIX at RHIC and by D0 at the run II of the Tevatron, we revisit the world prompt-photon data, both inclusive and isolated, in hadronic collisions, and compare them with the NLO QCD calculations implemented in the Monte Carlo program JETPHOX.

A critical phenomenological study of inclusive photon production in hadronic collisions

Abstract. We discuss fixed target and ISR inclusive photon production and attempt a comparison between theory and experiments. The dependence of the theoretical predictions on the structure functions, and on the renormalization and factorization scales is investigated. The main result of this study is that the data cannot be simultaneously fitted with a single set of scales and structure functions. On the other hand, there is no need for an additional primordial

Next-to-leading order determination of fragmentation functions

k_{_T}

Large-\(p_T\) inclusive \(\pi^0\) cross sections and next-to-leading-order QCD predictions

to force the agreement between QCD predictions and experiments, with the possible exception of one data set. Since the data cover almost overlapping kinematical ranges this raises the question of consistency among data sets. A comparative discussion of some possible sources of experimental uncertainties is sketched.

New NLO parameterizations of the parton distributionsin real photons

Abstract. We analyse LEP and PETRA data on single inclusive charged hadron cross-sections to establish new sets of Next-to-Leading order Fragmentation Functions. Data on hadro-production of large-

Parton distributions in the photon

p_{\bot}

Isolated prompt photon photoproduction at NLO

hadrons are also used to constrain the gluon Fragmentation Function. We carry out a critical comparison with other NLO parametrizations.

The gluon content of the pion from high-pt photon production

Abstract. We review the phenomenology of

Is a large intrinsic

\pi^0