HADRON COLLIDER PHYSICS: 15th Topical Conference on Hadron Collider Physics: HCP2004
753(2005); http://dx.doi.org/10.1063/1.1896687View Description Hide Description
The role of global QCD analysis of parton distribution functions (PDFs) in collider physics at the Tevatron and LHC is surveyed. Current status of PDF analyses are reviewed, emphasizing the uncertainties and the open issues. The stability of NLO QCD global analysis and its prediction on “standard candle” W/Z cross sections at hadron colliders are discussed. The importance of the precise measurement of various W/Z cross sections at the Tevatron in advancing our knowledge of PDFs, hence in enhancing the capabilities of making significant progress in W mass and top quark parameter measurements, as well as the discovery potentials of Higgs and New Physics at the Tevatron and LHC, is emphasized.
753(2005); http://dx.doi.org/10.1063/1.1896688View Description Hide Description
Fermilab will continue to maintain its pre‐eminent position in the world of High Energy Physics, with a unique opportunity to make unprecedented studies of the top quark and major discoveries, until the Large Hadron collider (LHC) at CERN becomes operational near the end of the decade. Run II is well underway with major accelerator and detector upgrades since Run I. A program of further upgrades to the accelerator complex will result in an integrated luminosity of 4–8 fb−1 per experiment, by the year 2009.
753(2005); http://dx.doi.org/10.1063/1.1896690View Description Hide Description
Standard parton shower monte carlos are designed to give reliable descriptions of low‐pT physics. In the very high‐energy regime of modern colliders, this is may lead to largely incorrect predictions of the basic reaction processes. This motivated the recent theoretical efforts aimed at improving monte carlos through the inclusion of matrix elements computed beyond the leading order in QCD. I briefly review the progress made, and discuss bottom production at the Tevatron.
753(2005); http://dx.doi.org/10.1063/1.1896691View Description Hide Description
Recent QCD measurements obtained by the CDF Collaboration at the Tevatron in pp̄ collisions at are presented. Results on inclusive jet physics are first reported. They include the measurement of the inclusive jet production cross section, a phenomenological study of the underlying event and the measurement of the jet shapes. Some specific processes of interest are then discussed. The measurements of W + jets, γγ and γ + heavy flavor productions are presented. Finally, the diffractive physics program is approached with reports on the measurements of the diffractive structure function and on the searches for exclusive final states.
753(2005); http://dx.doi.org/10.1063/1.1896692View Description Hide Description
We present recent QCD results from the DØ experiment at the Fermilab Tevatron Collider in pp̄ collisions at . Results are presented for the inclusive jet and dijet cross sections, a measurement of dijet azimuthal decorrelations, studies of elastic scattering, and a search for diffractively produced Z bosons.
A review of forward proton tagging at 420m at the LHC, and relevant results from the Tevatron and HERA753(2005); http://dx.doi.org/10.1063/1.1896693View Description Hide Description
We review the theoretical and experimental motivations behind recent proposals to add forward proton tagging detectors to the LHC experiments as a means to search for new physics. We also review the current diffractive programs at the Tevatron and HERA, focusing in particular on measurements which will have a direct impact on the case for forward detectors at the LHC.
753(2005); http://dx.doi.org/10.1063/1.1896694View Description Hide Description
Results from the Relativistic Heavy Ion Collider (RHIC) depict formation of a hot, dense system at an energy density greater than 5 GeV/fm3, well above that where hadrons exist. The measured relative particle abundances are reproduced by statistical‐thermal models with a temperature and baryo‐chemical potential at the quark‐hadron phase boundary predicted by lattice QCD. A large amount of collective flow is observed in collisions at RHIC and provides evidence of strong pressure gradients very early in the collision, at a time when the system is dense and highly interacting. Hard‐scattering, suppression of large transverse momentum hadrons, and quenching of di‐jets are observed in central Au + Au collisions but not in d + Au collisions, providing evidence for extreme energy loss of partons attempting to propagate through the hot, dense matter at RHIC.
753(2005); http://dx.doi.org/10.1063/1.1896695View Description Hide Description
The CDF and DØ Run II Tevatron experiments have measured inclusive W and Z boson production cross sections with pp̄ collisions at using leptonic decay modes. Other analyses including W charge asymmetry and forward‐backward asymmetries are also described in these proceedings. Neither experiment observes deviations from Standard Model predictions.
753(2005); http://dx.doi.org/10.1063/1.1896696View Description Hide Description
The Run II CDF and DØ experiments have measured the pp̄→Wγ cross sections with pp̄ collisions at using leptonic modes W → ev and W → μv. These measurements are in good agreement with the NLO theoretical predictions. The production cross sections of several other diboson processes pp̄→Zγ, WW,ZW,ZZ have been measured at CDF using W and Z leptonic modes with electrons and muons. The measurements establish the framework for future studies of the anomalous triple gauge couplings at the Tevatron Run 2.
753(2005); http://dx.doi.org/10.1063/1.1896697View Description Hide Description
The Tevatron Electroweak Working group was created in September, 2003 at Fermilab to consolidate electroweak physics results for precision Standard Model tests. It is the first combined analysis group at Fermilab to publish in a refereed journal. The group currently has 49 subscribers. Three subgroups are dedicated to studies of W and Z boson properties, top quark properties, and Higgs physics respectively. The group has produced combined results from the CDF and DØ experiments on the Run 1 W boson mass and width, the Run 1 top quark mass, and the Run 2 measurement of the ratio of W and Z boson cross sections. New results are anticipated as Run 2 analyses mature. The group also organizes joint workshops for theorists and experimentalists.
753(2005); http://dx.doi.org/10.1063/1.1896698View Description Hide Description
Success of precision studies in W and Z boson production at the Tevatron and LHC depends on the progress in reducing theoretical uncertainties to the level of 1 – 2%. I review recent developments in theoretical understanding of W and Z boson production and remaining issues to be solved to meet demands of the near‐future experiments.
753(2005); http://dx.doi.org/10.1063/1.1896699View Description Hide Description
We describe some recent progress in theoretical predictions for W and Z plus jet cross sections and related observables. In particular, we review some of the new NLO calculations that have been made in the last few years and analyze the impact of these results on analyses and phenomenology at the Tevatron Run II and the CERN LHC.
753(2005); http://dx.doi.org/10.1063/1.1896700View Description Hide Description
In these proceedings I explore one aspect of gauge‐boson physics at the LHC—Triple Gauge‐boson Couplings (TGCs) in WZ and Wγ production. Methods for extracting confidence limits on anomalous TGCs are assessed, while accounting for the effects of higher order QCD corrections and contributions from other theoretical and detector related systematics. Detector response has been parametrised according to the ATLAS detector’s specifications. A strategy for reporting the anomalous coupling limits is introduced which removes the ambiguities of form factors by reporting the limits as a function of a cutoff operating on the diboson system invariant mass. Techniques for measuring the energy dependence of anomalous couplings are demonstrated.
753(2005); http://dx.doi.org/10.1063/1.1896701View Description Hide Description
The large mass of the top quark, the only fermion to have a mass of the order of the electroweak scale, makes its study very important. This large mass implies that top is important for precision electroweak physics in the Standard Model, and may be the first indication that physics beyond the Standard Model may be evident in the detailed properties of top. This report, one of the plenary talks at the HCP 2004 conference, summaries our understanding of the top quark as of the year 2004, and shows how the current run II of the Fermilab Tevatron and the future planned CERN LHC experiments will, through detailed specific measurements, greatly improve our understanding of the top quark.
753(2005); http://dx.doi.org/10.1063/1.1896702View Description Hide Description
I report on preliminary measurements of the tt̄ production cross section, and a measurement of the top quark mass, performed by the DØ Collaboration. The cross section is measured using candidates for dilepton, single‐lepton, and all‐hadronic tt̄ decays collected at DØ during RunII of the Tevatron. The results for the various modes are:
The mass measurement uses an improved method to re‐analyze lepton+jets events collected during RunI of the Tevatron, and obtains mt = 180.1 ± 3.6 (stat.) ± 4.0 (syst.) GeV/c 2.
753(2005); http://dx.doi.org/10.1063/1.1896703View Description Hide Description
We present preliminary results on the search for electroweak single top quark production performed by the CDF and DØ collaboration at the Fermilab Tevatron collider. Using a dataset of approximately 160pb−1 we find no evidence for a single top quark signal and set 95% C.L. upper limits on the production cross sections: 8.5 pb for the t‐channel and 13.7 pb for the combined t‐ plus s‐channel search.
753(2005); http://dx.doi.org/10.1063/1.1896704View Description Hide Description
Recent preliminary results on top quark properties from the CDF and DØ collaborations at the Fermilab Tevatron are described. These analyses include: measurements of the ratio B(t → Wb)/B(t → Wq) and of B(t → τvq), search for anomalous kinematics, studies on the helicity of W bosons originating from top quark decays, spin correlations between top quark pairs, and searches for tt̄ resonance production in models beyond the standard model.