The Heavy Ion Physics Program with ATLAS at the LHC

The first Pb+Pb collisions at the Large Hadron Collider (LHC) at sqrts_NN = 5.52 TeV are imminent. Heavy ion collisions at the LHC provide an extended energy lever arm to the existing measurements made at RHIC and SPS, especially in hard (large-Q^2) processes. In this contribution an overview of the ATLAS detector is given and the current physics focus of Heavy Ion Working Group is discussed.Comment: 8 pages, 6 figures, prepared for the 23rd Winter Workshop on Nuclear Dynamics, Big Sky, MT, Feb 11-18, 200

Elucidating Jet Energy Loss in Heavy Ion Collisions

Very soon the LHC will provide beams for heavy ion collisions at 5.52 TeV/nucleon. This center-of-mass energy results in a large cross-section for producing high-$E_T$ ($>$ 50 GeV) jets that are distinct from the soft, underlying event. This brings with it the possibility of performing full jet reconstruction to directly study jet energy loss in the medium produced in heavy ion collisions. In this note, we present the current state of jet reconstruction performance studies in heavy ion events using the ATLAS detector. We also discuss the possibilities of energy loss measurements available with full jet reconstruction: single jet $R_{AA}$ and di-jet and $\gamma$-jet correlations.Comment: 3 pages, 4 figures, write up of poster presented at ICHEP 2008, Philadelphia, PA, July 29 - Aug. 5, 200

Total Cross-sections and Bloch-Nordsieck Gluon Resummation

The physics underlying the fall and eventual rise in various total cross-sections at high energies has been investigated over a decade using a model based on the Bloch-Nordsieck resummation in QCD. Here a brief review of our latest results is presented and comparison made with experimental data on $pp$, $\gamma proton$ and $\gamma \gamma$ total cross-sections.Comment: Presented by G. Pancheri at ISMD04, Sonoma State University. Under publication in Acta Physica Polonica. LaTeX format, 10 *.eps files, 7 page

Total cross sections and soft gluon resummation

We discuss a model for total hadronic and photonic cross-sections which includes hard parton-parton scattering to drive the rise and soft gluon resummation to tame it. Unitarity is ensured by embedding the cross-section in the eikonal formalism. Predictions for LHC and ILC are presented.Comment: 9 pages, 2 figures, Presented at PLC2005, Kazimierz, September 2005, requires appolb.cl

Total Cross-sections at very high energies: from protons to photons

A model for both proton and photon total cross-sections is presented and compared with data. The model is based on the eikonal representation, with QCD mini-jets to drive the rise and soft gluon kt-resummation into the Infrared region to tame the excessive rise due to low-x perturbative gluons. We discuss the effects of a singular but integrable expression for the Infrared gluon spectrum on the high energy behaviour of the total cross-section expected in this model.Comment: 13 pages, 4 figures, Tenth Workshop on Non-Perturbative Quantum Chromodynamics at l'Institut Astrophysique de Paris, June 8-12, 200

Total cross-section at LHC from minijets and soft gluon resummation in the infrared region

A model for total cross-sections incorporating QCD jet cross-sections and soft gluon resummation is described and compared with present data on $pp$ and ${\bar p}p$ cross-sections. Predictions for LHC are presented for different parameter sets. It is shown that they differ according to the small x-behaviour of available parton density functions.Comment: 10 pages, 3 figures, uses appolb.cls, LaTeX. Talk presented by G. Pancheri at the EURIDICE Final Meeting, August 24-27th, 2006, Kazimierz, Polan

Soft Gluons and the Energy Dependence of Total Cross-Sections

We discuss the high energy behaviour of total cross-sections for protons and photons, in a QCD based framework with particular emphasis on the role played by soft gluonsComment: 13 pages, 10 figures, Presented by G. Pancheri at the International Workshop on QCD, Martina Franca, Italy, June 16-20,2001. To appear in the proceeding

QCD Mini-jet contribution to the total cross section

We present the predictions of a model for proton-proton total cross-section at LHC. It takes into account both hard partonic processes and soft gluon emission effects to describe the proper high energy behavior and to respect the Froissart bound.Comment: 7 pages, 3 figures, presented at MPI08, Perugia, October 27-31, 200