P. Aurenche

Prompt Photon Production at Large p(T) Scheme Invariant QCD Predictions and Comparison with Experiment

Abstract On the basis of the complete QCD calculation up to second order in αs for hadronic production of prompt photons, a detailed quantitative discussion of the renormalization and factorization scheme dependence is presented. The algorithm of optimized perturbation theory is applied in order to constrain the predictions at this order. A quantitative comparison with all the presently available data for proton and pion induced processes is performed covering a large range in energy and transverse momentum. As a result a soft gluon distribution and a corresponding small value of the QCD scale Λ ( Λ MS ⩽ 200 MeV ) is favoured. Additional predictions for the forthcoming experiments are included. An outlook on further possible improvements of the analysis is given.

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.

Bremsstrahlung and photon production in thermal QCD

In this paper, we extend the study of bremsstrahlung photon production in a quark-gluon plasma to the cases of soft static photons

A critical phenomenological study of inclusive photon production in hadronic collisions

(\mathit{q}=0)

Prompt photon production at large pT in QCD beyond the leading order

and hard real photons. The general framework of this study is the effective perturbative expansion based on the resummation of hard thermal loops. Despite the fact that bremsstrahlung only comes at two loops, we find that in both cases, it generates contributions of the same order of magnitude as those already calculated by several other groups at one loop. Furthermore, a new process contained in the two-loop diagrams dominates the emission of a very hard real photon. In all cases, the rate of real or virtual photon production in the plasma is appreciably increased compared to the one-loop predictions.

A simple sum rule for the thermal gluon spectral function and applications

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

Scheme invariant higher order QCD predictions for large pT photoproduction reactions

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 The results of the complete O( α s 2 ) calculation of hadroproduction of prompt photons at large p T are presented. Good agreement with ISR data is obtained.

Landau-Pomeranchuk-Migdal resummation for dilepton production

In this paper, we derive a simple sum rule satisfied by the gluon spectral function at finite temperature. This sum rule is useful in order to calculate exactly some integrals that appear frequently in the photon or dilepton production rate by a quark gluon plasma. Using this sum rule, we rederive simply some known results and obtain some new results that would be extremely difficult to justify otherwise. In particular, we explain how this result can be used to calculate the photon rate in a simple quasi-particle model which correctly reproduces the thermodynamic properties of a quark-gluon plasma. We also derive an exact expression for the collision integral that appears in the calculation of the Landau-Pomeranchuk-Migdal effect and propose a method to solve the resulting differential equation.