41 research outputs found
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Measurement of the top quark mass in lepton+jets events with secondary vertex tagging
A measurement of the top quark mass with the matrix element method in the lepton + jets final state in D0 Run II is presented. Events with single isolated energetic charged lepton (electron or muon), exactly four calorimeter jets, and significant missing transverse energy are selected. Probabilities used to discriminate between signal and background are assumed to be proportional to differential cross-sections, calculated using event kinematics and folding in object resolutions and parton distribution functions. The event likelihoods constructed using these probabilities are varied with the top quark mass, m{sub t}, and the jet energy scale, JES, to give the smallest possible combined statistical + JES uncertainty
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Design and Implementation of the New D0 Level-1 Calorimeter Trigger
Increasing luminosity at the Fermilab Tevatron collider has led the D0 collaboration to make improvements to its detector beyond those already in place for Run IIa, which began in March 2001. One of the cornerstones of this Run IIb upgrade is a completely redesigned level-1 calorimeter trigger system. The new system employs novel architecture and algorithms to retain high efficiency for interesting events while substantially increasing rejection of background. We describe the design and implementation of the new level-1 calorimeter trigger hardware and discuss its performance during Run IIb data taking. In addition to strengthening the physics capabilities of D0, this trigger system will provide valuable insight into the operation of analogous devices to be used at LHC experiments
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Proposal to study multiparticle-peripheral hadron physics at NAL
We propose to build a large wire chamber magnetic spectrometer at NAL to measure multi-body forward-going hadronic systems produced by {pi}'s, K's and protons up to 80 GeV/c. Specific reactions will be isolated in order to study the s and t dependencies of the cross sections for peripheral processes, search for new resonant states and attempt to measure {pi}{pi} and K{pi} inelastic scattering. We propose a physics program for the spectrometer which is initially limited to those processes easiest to measure and which nevertheless spans a large range of strong interaction problems. Technically, the proposed spectrometer is a relatively modest extension of presently operating systems in the 10-20 GeV/c region, and does not present a challenge of uncertain magnitude to construct
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Top quark mass and kinematics
A summary of the results on the measurement of the Top Quark mass and the study of the kinematics of the t{bar t} system at the Tevatron collider is presented here. Results from both the CDF and D0 collaborations are reported
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The Road to the Higgs in collisions at = 1.96 TeV
Presented is a series of analyses which are central to the search for a low-mass Higgs boson. A search for ZZ production in the ZZ {yields} {ell}{sup -}{ell}{sup +}{nu}{bar {nu}} channel is introduced then the successful combination of this analysis with with the ZZ {yields} {ell}{sup +}{ell}{sup -}{ell}'{sup +}{ell}'{sup -} search to produce the first observation of the ZZ process at a hadron collider is then detailed. The final analysis presented is the search for the Higgs in the ZH {yields} {nu}{bar {nu}}b{bar b} channel and the interpretation as a ZZ {yields} {nu}{bar {nu}}b{bar b} search in order to validate the techniques. Common themes are discussed, such as multivariate techniques and instrumental backgrounds from energy measurement fluctuations and the tools used to combat them. The formalism of the statistical analysis of the final selected sample is introduced generally and demonstrated in the context of the above mentioned searches. The optimization of the selection through the identification of poorly reconstructed leptons is included as well as the utilization of b-quark identifying tools. Some space is given to jet reconstruction/identification and the Level 1 Calorimeter Trigger. The efficient identification and calibration of jets is central to many physics analysis especially in the low mass higgs search. Another key component of the ZH {yields} {nu}{bar {nu}}b{bar b} search is the proficient identification of jets and an imbalance of transverse energy in the first level of the triggering system. Therefore, the Level 1 Calorimeter Trigger, designed to achieve this, is a necessary component for a sensitive ZH {yields} {nu}{bar {nu}}b{bar b} search
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W and Z (plus jets) production and asymmetries at 1.96-TeV
This paper reviews the latest results from the Tevatron on W and Z physics, and their use as probes of QCD