J.Ph. Guillet

Spin effects with polarized protons at RHIC

Abstract We show that the use of RHIC as a polarized pp collider with a high designed luminosity will allow various interesting polarization studies. In particular, as we will see by considering several different reactions, this can help us to pin down the gluon polarized distribution function, to give a better insight for the u- and d-quarks polarization, to make dynamical tests of the Standard Model and to detect the possible existence of subconstituents.

Higher-order corrections to QCD jets

Abstract Motivated by recent calculations of matrix elements for O(α s 3 ) parton-parton scattering processes, we evaluate the K -factors and the relative transverse-momentum distributions for jet production at high p T . We present results for a set of parton-parton subprocesses involving quarks of different flavours, in the framework of a general analysis of all one-loop QCD corrections.

Jet production in hadronic collisions to0(α s 3 )

We present the full0(αs3) QCD corrections to jet production within a small opening angle δ at large transverse momenta for all partonic subprocesses. Results for CERN and Tevatron colliders are given with particular emphasis on the sensitivity to renormalization and factorization mass scales.

Higher order corrections to QCD jets: Gluon-gluon processes

Abstract We evaluate the full o(αs3) cross sections for the processes g+g→g+X and g+g→q+X, relevant for jet production at large pT at very high energies. Some phenomenological applications of our results at Sp p S and Tevatron energies are also presented.

ISOLATING PROMPT PHOTONS WITH NARROW CONES

A bstractWe discuss the isolation of prompt photons in hadronic collisions by means of narrow isolation cones and the QCD computation of the corresponding cross sections. We reconsider the occurence of large perturbative terms with logarithmic dependence on the cone size and their impact on the fragmentation scale dependence. We cure the apparent perturbative violation of unitarity for small cone sizes, which had been noticed earlier in next-to-leading-order (NLO) calculations, by resumming the leading logarithmic dependence on the cone size. We discuss possible implications regarding the implementation of some hollow cone variants of the cone criterion, which simulate the experimental difficulty to impose isolation inside the region filled by the electromagnetic shower that develops in the calorimeter.

Polarized deep inelastic scattering at collider energies

Abstract Spin asymmetries in deep inelastic scattering with longitudinally polarized electron and proton beams are examined. These predictions are a good testing ground for the nucleon spin structure and for the electroweak theory. Some of them will be measured in polarization experiments at future colliders.

A Way to Measure the Spin Dependent Distribution of the Gluon

In order to extract the spin-dependent distribution of the gluon, we calculate, in the photon-gluon model the leptoproduction of heavy quarkonia with both initial lepton and nucleon longitudinally polarized. We give some predictions for the EMC experiment.

Next-to-leading order QCD corrections to pp --> b anti-b b anti-b + X at the LHC: the quark induced case

Abstract The production of two b b ¯ pairs is a prominent background for Higgs and New Physics searches in various extensions of the Standard Model. We present here the next-to-leading order QCD corrections to the quark induced subprocess using the GOLEM approach for the virtual corrections. We show that our result considerably improves the prediction and conclude that the inclusion of next-to-leading order effects is indispensable for reliable studies of b b ¯ b b ¯ observables in hadronic collisions.

Hadronic colliders as probes of the proton spin structure

AbstractWe perform a systematic analysis of different processes with high energy polarized proton beams: jets, direct photon, lepton pairs (Drell-Yan) andWZ production. Different sets of polarized partonic densities are used that fit EMC and SLAC polarized deep inelastic scattering data with variable amount of quark and gluon components of the proton spin. The case of the future Relativistic Heavy Ion Collider (RHIC) used as a polarized collider at a maximum energy of