Isolated-photon production in polarized hadronic collisions

After a short discussion on the definition of isolated-photon cross sections in perturbative QCD, I present phenomenological predictions relevant for polarized hadron-hadron collisions in the RHIC energy range. The possibility of measuring $\Delta g$ is investigated.Comment: 3 pages Latex; npb.sty and 2 ps figures included. Talk given at DIS99, 19 - 23 April 1999, Zeuthen, D

Isolated photons in perturbative QCD

I present a definition of the cross section for the production of an isolated photon plus $n$ jets which only depends upon direct photon production, and it is independent of the parton-to-photon fragmentation contribution. This prescription, based on a modified cone approach which implements the isolation condition in a smooth way, treats in the same way quarks and gluons and can be directly applied to experimental data in hadron-hadron, photon-hadron and \epem collisions. The case of several, isolated photons in the final state can also be dealt with in the very same way.Comment: 10 pages Late

Matching NLO QCD computations with PYTHIA using MC@NLO

We present the matching between a next-to-leading order computation in QCD and the PYTHIA parton shower Monte Carlo, according to the MC@NLO formalism. We study the case of initial-state radiation, and consider in particular single vector boson hadroproduction.Comment: 16 pages, 10 figures. Several comments and two figures have been adde

Constraints on the polarized gluon density in the proton from charm photoproduction

We consider the possibility of a direct determination of the polarized gluon density in the proton using charm production with polarized beams at HERA. We study total cross sections and distributions at leading order using different parametrizations of the polarized gluon density. We conclude that charm photoproduction data can be used to constrain the polarized gluon density in the proton if an integrated luminosity of 100~pb$^{-1}$ will be achieved at HERA.Comment: 13 pages Latex, uses epsfig.sty, 3 eps figures appended as uuencoded, gzipped, tarred fil

Higher-order QCD corrections to γ∗γ∗→hadrons\gamma^*\gamma^*\to hadrons

I illustrate the techniques and the results of the computation of order-\as corrections to the production of hadrons in the collision of two virtual photons, that originate from the incoming leptons at \epem colliders.Comment: 5 pages Latex; espcrc2.sty and three ps figure included. Talk given at QCD00, 6 - 12 July 2000, Montpellier, Franc

A Positive-Weight Next-to-Leading-Order Monte Carlo for Heavy Flavour Hadroproduction

We present a next-to-leading order calculation of heavy flavour production in hadronic collisions that can be interfaced to shower Monte Carlo programs. The calculation is performed in the context of the POWHEG method. It is suitable for the computation of charm, bottom and top hadroproduction. In the case of top production, spin correlations in the decay products are taken into account.Comment: 18 pages, 12 figures. Few misprints corrected, references updated, final remarks adde