Searcharxiv⌕ Search

arXiv subjects

S. Frixione

Publications and source records attributed to S. Frixione.

At least 73 records · Page 4Linked to original sources
arXiv2000

The QCD and Standard Model Working Group: Summary Report from Les Houches

The Les Houches Workshop on Physics at TeV Colliders took place from June 8-18, 1999. One of the three working groups at Les Houches concentrated on QCD issues, both at the Tevatron Collider and at the LHC. Besides the interest in QCD in its own right, QCD dynamics plays an important role in the production mechanisms for any new physics process that might be observed at either collider, as well as any processes that may form backgrounds to the new physics. This writeup serves both as a pedagogical overview of QCD as well as an update on the current status of the field.

hep-ph↗
arXiv2000

QCD

We discuss issues of QCD at the LHC including parton distributions, Monte Carlo event generators, the available next-to-leading order calculations, resummation, photon production, small x physics, double parton scattering, and backgrounds to Higgs production.

hep-ph↗
arXiv1999

A note on the production of photons at RHIC

I study the production of prompt photons in polarized hadronic collisions, considering different isolation prescriptions. In particular, I focus on the problem of the measurability of the polarized gluon density in the proton through isolated-photon data.

hep-ph↗
arXiv1999

Heavy quark photoproduction

I present a review of selected topics in the computation of heavy flavour cross sections in photon-hadron collisions.

hep-ph↗
arXiv1999

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 $Δg$ is investigated.

hep-ph↗
arXiv1999

Jet cross sections in polarized photon-hadron collisions

We present a computation of one- and two-jet cross sections in polarized photon-hadron collisions, which is accurate to next-to-leading order in QCD. Our results can be used to compute photoproduction cross sections in electron-proton scattering. To this purpose, we investigate the structure of the polarized Weizsaecker-Williams function, where we include a universal, non-logarithmic term, neglected in the literature. We construct a Monte Carlo code, within the framework of the subtraction method, and we use it to study the phenomenology of jet production in the energy range relevant to HERA. In particular, we investigate the perturbative stability of our results, and we discuss the possibility of constraining polarized parton densities of the proton and the photon using jet data.

hep-ph↗
arXiv1998

Isolated photons without fragmentation contribution

I illustrate how to define an isolated-photon cross section which is independent of the parton-to-photon fragmentation contribution, it is infrared safe to all orders in perturbative QCD, and it is exclusive in the kinematical variables of the photon and of the accompanying jets. This isolation prescription is applicable to any kind of polarized or unpolarized hard collisions. It can also be used without any modifications in the case of two or more isolated photons in the final state. I present results for one-photon production in hadronic collisions, and I compare them with existing results obtained in the framework of the conventional cone approach.

hep-ph↗
arXiv1998

Problems in the resummation of soft-gluon effects in the transverse-momentum distributions of massive vector bosons in hadronic collisions

We consider the resummation of soft-gluon emission in the transverse-momentum distribution of vector mesons in hadronic collisions. We find that the resummed expression in the impact-parameter formulation has an expansion in $\as$ with factorially growing terms with oscillating signs. These diverging terms arise from the small impact-parameter region of integration, and are of a subleading nature. We also obtain a closed expression for the next-to-leading logarithm resummation in $\qt$-space, and we study its analytic structure. We find in this case that, although no factorially growing terms are present, there are geometrical singularities that severely restrict the range of applicability of the resummation formula.

hep-ph↗
arXiv1998

Next-to-leading order jet cross sections in polarized hadronic collisions

We present a next-to-leading order computation in QCD of one-jet and two-jet cross sections in polarized hadronic collisions. Our results are obtained in the framework of a general formalism that deals with soft and collinear singularities using the subtraction method. We construct a Monte Carlo program that generates events at the partonic level. We use this code to give phenomenological predictions for $pp$ collisions at $\sqrt{S}=500$ GeV, relevant for the spin physics program at RHIC. The possibility of using jet data to constrain the poorly known polarized parton densities is examined.

hep-ph↗
arXiv1998

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.

hep-ph↗
arXiv1997

Heavy-Quark Production

We review the present theoretical and experimental status of heavy quark production in high-energy collisions. In particular, we cover hadro- and photoproduction at fixed target experiments, at HERA and at the hadron colliders, as well as aspects of heavy quark production in e+e- collisions at the Z0 peak.

hep-ph↗
arXiv1997

Jet photoproduction at HERA

We compute various kinematical distributions for one-jet and two-jet inclusive photoproduction at HERA. Our results are accurate to next-to-leading order in QCD. We use the subtraction method for the cancellation of infrared singularities. We perform a thorough study of the reliability of QCD predictions; in particular, we consider the scale dependence of our results and discuss the cases when the perturbative expansion might break down. We also deal with the problem of the experimental definition of the pointlike and hadronic components of the incident photon, and briefly discuss the sensitivity of QCD predictions upon the input parameters of the calculation, like $α_S$ and the parton densities.

hep-ph↗
arXiv1997

A general approach to jet cross sections in QCD

I illustrate a general formalism based upon the subtraction method for the calculation of next-to-leading order QCD cross sections for any number of jets in any type of hard collisions. I discuss the implementation of this formalism in a numerical program which generates partonic kinematical configurations with an appropriate weight, thus allowing the definition of arbitrary jet algorithms and cuts matching the experimental setup at the last step of the computation. I present results obtained with computer codes which calculate one-jet and two-jet inclusive quantities in photon-hadron and hadron-hadron collisions.

hep-ph↗
arXiv1996

Prospects for heavy flavour photoproduction at HERA

I discuss few selected topics in heavy flavour photoproduction at HERA which require large integrated luminosity in order to be experimentally investigated. I present phenomenological predictions for bottom production. As a possible application of measurements involving double-tagged charm events, I outline a method for the direct measurement of the gluon density in the proton. The possibility of using charm data in polarized electron-proton collisions to constrain the polarized gluon density in the proton is also discussed.

hep-ph↗
arXiv1996

Heavy flavour production

We discuss the impact of the planned upgrades of the HERA collider on the study of open heavy flavour and quarkonium production. New experimental techniques in charm physics are presented.

hep-ph↗
arXiv1996

Bottom production in hadronic collisions

I review the status of the comparison between theoretical predictions and experimental results for bottom production in hadronic collisions, and discuss the possible sources of the discrepancies found. The study of jets containing bottom quarks is proposed as a promising tool to investigate the $b$ production mechanism. I present next-to-leading order QCD predictions for this process, and compare them with data.

hep-ph↗
arXiv1996

Heavy-quark jets in hadronic collisions

We present a next-to-leading order QCD calculation of the production rates of jets containing heavy quarks. This calculation is performed using the standard Snowmass jet algorithm; it therefore allows a comparison with similar results known at next-to-leading order for generic jets. As an application, we present results for the inclusive transverse energy of charm and bottom jets at the Tevatron collider, with a complete study of the dependence on the jet cone-size and of the theoretical uncertainties.

hep-ph↗