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Top properties at the Tevatron

Description: We present the latest results associated with top properties at the Tevatron. The large data set collected in four years of running has allowed, after top discovery, the study of various top properties. The results presented here include the measurement of the CKM matrix element {vert_bar}V{sub if}{vert_bar}, the search for top FCNC, the study of properties of W in t decays and the search for heavy states decaying to tt pairs. Future measurements in top physics at the Tevatron are briefly discussed.
Date: May 1, 1997
Creator: Chiarelli, G. & Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Infrared fixed point solution for the top quark mass and unification of couplings in the MSSM

Description: We analyze the implications of the infrared quasi fixed point solution for the top quark mass in the Minimal Supersymmetric Standard Model. This solution could explain in a natural way the relatively large value of the top quark mass and, if confirmed experimentally, may be suggestive of the onset of nonperturbative physics at very high energy scales. In the framework of grand unification, the expected bottom quark -- tau lepton Yukawa coupling unification is very sensitive to the fixed point structure of the top quark mass. For the presently allowed values of the electroweak parameters and the bottom quark mass, the Yukawa coupling unification implies that the top quark mass must be within ten percent of its fixed point values.
Date: August 1, 1993
Creator: Bardeen, W.A.; Carena, M.; Pokorski, S. & Wagner, C.E.M.
Partner: UNT Libraries Government Documents Department

Measurement of the t{bar t} production cross section at the Tevatron

Description: We report on the measurement of the t{anti t} production cross section obtained by CDF and D0 experiments with p{anti p} collisions at {radical}s=1. 8 TeV. The analyses presented here refer to {integral} Ldt {approx}11O pb{sup -1} collected at the Fermilab Tevatron collider during the run 1992-96. About 85% of the possible t{anti t} decays have been studied in different channels classified according to the number of high P{sub T} leptons found in the final state. The production cross section has been measured in each individual channel and then combined into a single value for each experiment, which is {sigma}{sub tt} = 7.5{sup 1.9}{sub 1.6} pb for CDF and {sigma}{sub tt} = 5.77 {+-} 1.76 pb for D0.
Date: May 1, 1997
Creator: Castro, A. & Collaborations, CDF and DO
Partner: UNT Libraries Government Documents Department

Measuring the CKM matrix element V{sub tb} at D-zero and CDF

Description: I present measurements by the CDF collaboration of the Standard Model three generation CKM matrix element V{sub tb} and of a special case extension with additional assumptions, using current Tevatron t{anti t} data. I then show how we can significantly improve the precision on V{sub tb} and at the same time extend the measurement so it is not constrained by Standard Model assumptions, using single top production at the upgraded Tevatron.
Date: July 1, 1997
Creator: Heinson, A.P.
Partner: UNT Libraries Government Documents Department

Search for light top squarks with the D{O} detector

Description: We present preliminary results of a search for pair produced top squarks, the supersymmetric partners to the top quark, under the assumption that the two-body decay {bar t}{sub 1} {yields} b{bar W}{sub 1} and three-body decay {bar t}{sub 1} {yields} bW{bar Z}{sub 1} are kinematically forbidden. This scenario is realized if {bar t}{sub 1} is considerably lighter than all other squarks as well as {bar W}{sub 1}, all {bar v}s, and the top quark. Such light top squarks will dominantly decay via {bar t}{sub 1} {yields} c{bar Z}{sub 1} yielding a signal of two acollinear jets with (E){sub T}. The data reported here were taken during the 1992-1993 run of the D0 detector at the Fermilab Tevatron p{bar p} collider operating at {radical}s = 1.8 TeV.
Date: July 1, 1995
Creator: Abachi, S.
Partner: UNT Libraries Government Documents Department

D{O} top quark mass analysis

Description: Based on (44-48 pb{sup -1}) of lepton + jets data, we review D0`s initial analysis of the top quark mass. The result, M{sub top} = 199 {+-} 19/21 (stat.) {+-} 22 (syst.) GeV/c{sup 2}, is insensitive to background normalization. The errors are based on ISAJET top Monte Carlo, with its more severe gluon radiation, and allow for ISAJET/HERWIG differences. Good progress is being made in reducing the systematic error. We present a new study based on two-dimensional distributions of reconstructed top quark vs. dijet mass. With 98.7% confidence we observe a peak in the top mass - dijet mass plane. The peak and its projections are similar both in shape and magnitude to expectations based on the decay sequence 1 {yields} bW, W {yields} jj.
Date: July 1, 1995
Creator: Strovink, M.
Partner: UNT Libraries Government Documents Department

A measurement of the top-antitop production cross section in the dimuon final state with the D0 detector for proton-antiproton collisions as s**(1/2) = 1.96 TeV

Description: A measurement of the top pair production cross section in the dimuon final state for proton-antiproton collisions at ps = 1:96 TeV is presented. Approximately 420 pb{sup -1} of data collected with the Run II D{O} detector are used for this measurement. Two data events are observed with a total expected signal plus background yield of 3.6 events. Assuming a top mass of 175 GeV, the measured cross section is: {sigma}{sub {bar u}} = 3.13{sup +4.17}{sub -2.60}(stat){sup +0.92}{sub -0.86}(sys){+-}0.19(lumi)pb, which is consistent with a NNLO prediction of 6.77 {+-} 0.42 pb.
Date: December 1, 2006
Creator: Burke, Susan Elizabeth & U., /Arizona
Partner: UNT Libraries Government Documents Department

Electro symmetry breaking and beyond the standard model

Description: The development of the Standard Model of particle physics is a remarkable success story. Its many facets have been tested at present day accelerators; no significant unambiguous deviations have yet been found. In some cases, the model has been verified at an accuracy of better than one part in a thousand. This state of affairs presents our field with a challenge. Where do we go from here? What is our vision for future developments in particle physics? Are particle physicists` recent successes a signal of the field`s impending demise, or do real long-term prospects exist for further progress? We assert that the long-term health and intellectual vitality of particle physics depends crucially on the development of a new generation of particle colliders that push the energy frontier by an order of magnitude beyond present capabilities. In this report, we address the scientific issues underlying this assertion.
Date: May 1, 1995
Creator: Barklow, T.; Dawson, S.; Haber, H.E. & Siegrist, J.
Partner: UNT Libraries Government Documents Department

VIIth Blois Workshop summary: experimental

Description: The Blois Workshop has become a conference not just restricted to diffractive scattering, but including topics such as searches for SUSY and Higgs, measurements of the top mass and b-decays. I will mention these briefly but will mostly discuss new results (and needed future measurements) in hard diffraction at HERA and the Tevatron.
Date: October 1, 1997
Creator: Albrow, M.G.
Partner: UNT Libraries Government Documents Department

Exploiting the single-lepton event structure in the search for the top quark

Description: We discuss whether the event structure can be useful in searching for the top quark in the single-lepton channel at the Tevatron, where the main obstacle is a considerable background from QCD W+ multijet production. We restrict our discussion to the case of a Standard Model top quark of heavy mass, M{sub top}>100 GeV.
Date: June 1, 1993
Creator: Cobal, M.; Leone, S. & Grassman, H.
Partner: UNT Libraries Government Documents Department

Observation of the top quark

Description: The D0 collaboration reports on a search for the Standard Model top quark in p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb{sup {minus}1}. We have searched for t{bar t} production in the dilepton and single lepton decay channels, with and without tagging of b quark jets. We observe 17 events with an expected background of 3.8 {plus_minus} 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 {times} 10{sup {minus}6} (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199{sub {minus}21}{sup +19} (stat.) {plus_minus}22 (syst.) GeV/c{sup 2} and its production cross section to be 6.4 {plus_minus} 2.2 pb.
Date: May 1, 1995
Creator: Klima, B.
Partner: UNT Libraries Government Documents Department

Top decay physics at CDF and measurement of the CKM element V{sub tb}

Description: Now that the top quark`s existence has been firmly established by the CDF and D0 experiments{sup 1,2)}, we begin to measure its properties. Branching fractions are of particular interest in the case of the t quark, since they probe the couplings of the top quark to gauge bosons and other quarks, and because ``the top quark is the only quark with reasonable mass``{sup 3)}. Because the top quark is the only quark with mass comparable to the electroweak scale, its decays, particularly non-standard decays, might shed some light on what makes the top quark different from lighter quarks, and the role it plays in electroweak symmetry breaking. This paper describes some recent measurements on the decay of the top quark using the CDF detector, a general purpose detector designed to study p{bar p} collisions at {radical}s=1.8 TeV; it has been described in detail elsewhere{sup 4,1)}. The analyses presented use 100-110 pb{minus}{sup 1} of data collected between 1992 and 1995 at the Fermilab TeVatron.
Date: December 1995
Creator: LeCompte, T. J.
Partner: UNT Libraries Government Documents Department

CDF top quark production and mass

Description: The top search in the dilepton and lepton plus jets channels with the Collider Detector at Fermilab is presented. The analysis uses a 67 pb{sup {minus}1} sample of p{bar p} collisions at 1.8 TeV. A 4.8{sigma} excess of candidate events establishes the existence of the top quark. The t{bar t} production cross section is measured to be {sigma}{sub t{bar t}} = 7.6{sub {minus}2.0}{sup +2.4} pb with branching Br(t {yields} Wb) = 0.87{sub {minus}0.30}{sup +0.13}(stat) {sub {minus}0.11}{sup +0.13}(syst). The measured mass is M{sub top} = 176{plus_minus}8{plus_minus}10 GeV.
Date: July 18, 1995
Creator: Incandela, J.
Partner: UNT Libraries Government Documents Department

Results on top quark production from D0

Description: The D{O} Collaboration reports on a search for the Standard Model top quark in p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb{sup -1}. We have searched for t{bar t} production in the dilepton and single lepton channels with and without tagging of b quark jets. We observe 17 events with an expected background of 3.8 {plus_minus} 0.6 events. The probability for an upward, fluctuation of the background to produce the observed signal is 2 x 10{sup -6} (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199{sub -21}{sup +19}(stat.){plus_minus}22 (syst.) GeV/c{sup 2} and its production cross section to be 6.4 {plus_minus} 2.2 pb.
Date: August 1, 1995
Creator: Wimpenny, S.J.
Partner: UNT Libraries Government Documents Department

Top quark physics

Description: Most of the material presented in this report, comes from contributions to the parallel session PL20 of this conference. We summarise the experimental results of direct production of Top quarks, coming from the CDF and C0 Collaborations at Fermilab, and compare these results to what one expects within current theoretical understanding. Particular attention is given to new results such as all hadronic modes of t{bar t} decay. As far as the mass is concerned, a comparison is made with precision measurements of related quantities, coming from LEP and other experiments. An attempt is made to look at the medium-term future and understand which variables and with what accuracy one can measure them with increased integrated luminosity.
Date: October 1, 1995
Creator: Menzione, A.
Partner: UNT Libraries Government Documents Department

Observation of the top quark

Description: The DO collaboration reports on a search for the Standard Model top quark in p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron, with an integrated luminosity of approximately 50 pb{sup {minus}1}. We have searched for t{bar t} production in the dilepton and single-lepton decay channels, with and without tagging of b quark jets. We observe 17 events with an expected background of 3.8 {plus_minus} 0.6 events. The probability for an upward fluctuation of the background to produce the observed signal is 2 {times} 10{sup {minus}6} (equivalent to 4.6 standard deviations). The kinematic properties of the excess events are consistent with top quark decay. We conclude that we have observed the top quark and measure its mass to be 199{sub {minus}21}{sup +19} (stat.) {plus_minus}22 (syst.) GeV/c{sup 2} and its production cross section to be 6.4 {plus_minus} 2.2 pb.
Date: May 1, 1995
Creator: Greenlee, H.
Partner: UNT Libraries Government Documents Department

Top physics prospects in Run II and TeV33

Description: The top production rate in the future Tevatron run at {radical}s = 2 TeV with the increased luminosity is summarized. The expected yield seen by the upgraded detectors which have larger acceptance and better efficiency will give statistical and systematic improvements for various top decay properties and standard model values.
Date: July 1, 1996
Creator: Byon-Wagner, A.
Partner: UNT Libraries Government Documents Department

High energy physics

Description: Hadron collider studies will focus on: (i) the search for the top quark with the newly installed D0 detector at the Fermilab Tevatron collider, (ii) the upgrade of the D0 detector to match the new main injector luminosity and (iii) R&D on silicon microstrip tracking devices for the SSC. High statistics studies of Z{sup 0} decay will continue with the OPAL detector at LEP. These studies will include a direct measurement of Z decay to neutrinos, the search for Higgs and heavy quark decays of Z. Preparations for the Large Scintillation Neutrino Detector (LSND) to measure neutrino oscillations at LAMPF will focus on data acquisition and testing of photomultiplier tubes. In the theoretical area E. Ma will concentrate on mass-generating radiative mechanisms for light quarks and leptons in renormalizable gauge field theories. J. Wudka`s program includes a detailed investigation of the magnetic-flip approach to the solar neutrino.
Date: July 1, 1997
Creator: Kernan, A.; Shen, B.C. & Ma, E.
Partner: UNT Libraries Government Documents Department

Review of scientific and technical options for the Superconducting Super Collider Program

Description: This document is a review of options for the Superconducting Super Collider (SSC) Program. It is the result of an informal study by an ad-hoc working group consisting of Laboratory physicists and engineers who investigated the physics and technical implications of a number of possible alternative SSC programs. Previous studies have shown, and early in this study it was confirmed, that a collider of approximately 20 TeV protons on 20 TeV protons with a luminosity of 10{sup 33} cm{sup {minus}2}s{sup {minus}1} at each interaction region is needed to support a physics program that is guaranteed to answer existing particle physics questions and make new discoveries. Therefore, all options considered in this document were consistent with attainment of these original goals for the SSC. One promising option considered was a program of colliding anti-protons on protons as a possible means to reduce the cost of the SSC by eliminating one of the Collider rings. However, the luminosity requirements to obtain the SSC physics goals remains the same as for protons colliding with protons and this study confirms that even though progress has been made over the last ten years in obtaining the high intensity anti-proton beams necessary, a luminosity higher than 10{sup 32} cannot be guaranteed. Other options were examined to see what advantages could be derived by departing from the SSC baseline program, either in schedule, in parameters, by staging, or by combinations of these options. Even though we considered re-examination of the cost of the baseline program to be beyond the scope of this document, differential cost savings were estimated. Finally, a brief survey of progress over the last ten years in various technical areas that might lead to more cost effective engineering designs was included in this study, such as higher magnetic field magnets resulting from lower operating ...
Date: November 1, 1993
Creator: Dombeck, T.
Partner: UNT Libraries Government Documents Department

High p{sub t} physics processes

Description: In order to estimate the ``physics reach`` of various pp or {bar p}p colliders, several physics processes of interest have been studied. For each process, the number of produced events required to carry out meaningful.physics studies or detect statistically significant signals has been estimated. These estimates are largely based on detailed studies for the SDC and GEM design reports. Extrapolation to other energies takes into account calculated cross sections and crude background estimates. To convert the required number of events into an average luminosity to be delivered by the machine, a ``running year`` of 10{sup 7} seconds is used. This time is consistent with SSC design plans, which call for an 80% detector up time and enough stable beam time to result in 10{sup 7} ``live`` seconds per operating year. Note that when making comparisons with existing facilities, any deviation from these assumptions should be taken into account. The conclusions of this study are generally sim-ilar to those reached by Eichten, et al. in 1984 and by the Drell Panel in 1990.
Date: October 1, 1993
Creator: Bird, F.; Blocker, C.; Fukui, T.; McBride, P.; Paige, F.; Pal, T. et al.
Partner: UNT Libraries Government Documents Department

ElectroWeak symmetry breaking in Tevatron Run II

Description: The Tevatron Run II will provide CDF and D0 with a large dataset of p{bar p} interactions collected at {radical}s = 2 TeV. They discuss the opportunity for the two experiments to improve the understanding of electroweak and top physics in the first years of data taking (Run IIa, 2fb{sup -1}) in view of the upgrades of the detectors. They also discuss the prospectives for a Higgs discovery at the Tevatron in view of the Run IIb data taking period which will deliver an additional of about 13 fb{sup -1} to each experiment.
Date: November 27, 2001
Creator: Chiarelli, G.
Partner: UNT Libraries Government Documents Department

Kinematic top analyses at CDF

Description: We present an update of the top quark analysis using kinematic techniques in p{bar p} collisions at {radical}s = 1.8 TeV with the Collider Detector at Fermilab (CDF). We reported before on a study which used 19.3 pb{sup {minus}1} of data from the 1992--1993 collider run, but now we use a larger data sample of 67 pb{sup {minus}1}. First, we analyze the total transverse energy of the hard collision in W+{ge}3 jet events, showing the likely presence of a t{bar t} component in the event sample. Next, we compare in more detail the kinematic structure of W+ {ge}3 jet events with expectations for top pair production and with background processes, predominantly direct W+ jet production. We again find W+ {ge} 3 jet events which cannot be explained in terms of background, but show kinematic features as expected from top. These events also show evidence for beauty quarks, in agreement with expectations from top, but not compatible with expectations from backgrounds. The findings confirm the observation of top events made earlier in the data of the 1992--1993 collider run.
Date: March 1, 1995
Creator: Grassmann, H.
Partner: UNT Libraries Government Documents Department