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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

[High Energy Physics Program at the University of Alabama. Final report]

Description: The High Energy Physics group at University of Alabama is a member of the L3 collaboration studying e+e{minus} collisions near the Z{degree} pole at the LEP accelerator at CERN. About 2 million Z{degree} events have been accumulated and the experiment has been prolific in publishing results on the Z resonance parameters, the Z couplings to all leptons and quarks with mass less than half the Z mass, searches for new particles and interactions, and studies of strong interactions and/or weak charged current decays of the quarks and leptons abundantly produced in Z decays. The group is contributing to data analysis as well as to detector hardware. In particular, the authors are involved in a major hardware upgrade for the experiment, namely the design, construction and commissioning of a Silicon Microvertex Detector (SMD) which has successfully been installed for operation during the present grant period. The authors present here a report on their recent L3 activities and their plans for the next grant period of twelve months (April 1, 1994--March 31, 1995). Their main interests in data analysis are in the study of single photon final states and the physics made more accessible by the SMD, such as heavy flavor physics. Their hardware efforts continue to be concentrated on the high precision capacitive and optical alignment monitoring systems for the SMD and also includes gas monitoring for the muon system. They are also planning to participate in the coming upgrade of the L3 detector.
Date: October 1, 1993
Creator: Baksay, L. & Busenitz, J.K.
Partner: UNT Libraries Government Documents Department

Overview of the GEM muon system cosmic ray test program at the SSCL

Description: Muon track resolution exceeding 75-{mu}m per plane is one of the main strengths of the GEM detector design, and will be crucial in searches for Higgs Bosons, heavy Z-Bosons, technicolor, and supersymmetry. Achieving this resolution coal requires improved precision in muon chambers and their alignment. A cosmic ray test stand known as the Texas Test Rio, (TTR) has been created at the SSCL for studying candidate GEM muon chamber technologies. Test results led to selecting Cathode Strip Chambers (CSC) as the GEM muon system baseline chamber technology.
Date: April 1, 1993
Creator: Milner, E.C.
Partner: UNT Libraries Government Documents Department

e[sup [plus]]e[sup [minus]] linear colliders and new particle searches

Description: We discuss future e[sup +]e[sup [minus]] linear colliders and new particle searches that can be done with them. In the discussion of new particle searches we examine the following topics: searches for gauge boson structure, searches for a strongly interacting Higgs sector, top quark studies, Higgs searches, supersymmetric particle searches and measurements of soft supersymmetry breaking parameters.
Date: January 1, 1993
Creator: Barklow, T.L.
Partner: UNT Libraries Government Documents Department

Strange meson spectroscopy in K[omega] and K[phi] at 11 GeV/c and Cherenkov ring imaging at SLD

Description: This thesis consists of two independent parts; development of Cherenkov Ring Imaging Detector (CRID) system and analysis of high-statistics data of strange meson reactions from the LASS spectrometer. Part 1: The CRID system is devoted to charged particle identification in the SLAC Large Detector (SLD) to study e[sup +]e[sup [minus]] collisions at [radical]s = m[sub Z[sup 0]]. By measuring the angles of emission of the Cherenkov photons inside liquid and gaseous radiators, [pi]/K/p separation will be achieved up to [approximately]30 GeV/c. The signals from CRID are read in three coordinates, one of which is measured by charge-division technique. To obtain a [approximately]1% spatial resolution in the charge-division, low-noise CRID preamplifier prototypes were developed and tested resulting in <1000 electrons noise for an average photoelectron signal with 2 [times] 10[sup 5] gain. To help ensure the long-term stability of CRID operation at high efficiency, a comprehensive monitoring and control system was developed. Part 2: Results from the partial wave analysis of strange meson final states in the reactions K[sup [minus]]p [yields] K[sup [minus]][omega]p and K[sup [minus]]p [yields] [bar K][sup 0][phi]n are presented. The analyses are based on data from a 4.1 event/nb exposure of the LASS spectrometer in K[sup [minus]]p interactions at 11 GeV/c. The data sample of K[sup [minus]][omega]p final state contains [approximately]10[sup 5] events. From the partial wave analysis, resonance structures of J[sup P] = 2[sup [minus]], 3[sup [minus]] and 2[sup +] amplitudes are observed in the K[omega] system. The analysis of 2[sup [minus]] amplitudes provides an evidence for two strange meson states in the mass region around 1.75 GeV/c[sup 2]. The appropriate branching fractions are calculated and compared with the SU(3) predictions. The partial wave analysis of [bar K][sup 0][phi] system favors J[sup P] = 1[sup [minus]] and 2[sup +] states in the 1.9--2.0 GeV/c[sup 2] region.
Date: January 1, 1993
Creator: Kwon, Youngjoon.
Partner: UNT Libraries Government Documents Department

A search for the top quark decaying to charged Higgs in p{bar p} collisions at {radical}s = 1.8 TeV

Description: We present results of a search for the top quark decaying to a charged. Higgs boson (H) in p{bar p} collisions at {radical}s = 1.8 TeV at the Fermilab Tevatron. Using 4.1 pb{sup {minus}1} of data collected during the 1988--1989 CDF run, we have searched for evidence of t{bar t} production assuming that t{r_arrow} Hb and H{r_arrow} {tau}{nu}{sub {tau}}. We find no evidence for this decay and are able to exclude regions in the (m{sub t}, m{sub H}) plane for different Br(H{r_arrow} {tau}{nu}{sub {tau}}). We also interpret these results for the two Higgs doublet(THD) model.
Date: August 1, 1993
Creator: Collaboration, CDF
Partner: UNT Libraries Government Documents Department

Search for the top quark and other new particles at D0

Description: Preliminary results from the search for the top quark and other new particles in p[bar p] collisions at [radical]s = 1.8 TeV are reported. In a data sample corresponding to an integrated luminosity of about 7.5 pb[sup [minus]1], one candidate event for top quark is found in the di-lepton channel. A lower limit for the mass of the top quark of 103 GeV/c[sup 2] (99 Gev/c[sup 2]) is obtained at 95% confidence level with (without) background subtraction. Status of searches for other new particles that may arise from new phenomena beyond the standard model is summarized.
Date: September 1, 1993
Creator: Bhat, P.C.
Partner: UNT Libraries Government Documents Department

Duke University High Energy Physics; Progress report, December 1, 1990--March 15, 1993

Description: The research program of the Duke High Energy Physics Group is described in this Progress Report and a separate Proposal containing their plans for 1994. These two documents are supplemented by compilations of selected publications, thesis abstracts, and the curriculum vitae of the eleven Ph.D. physicists who are carrying out this research program. This Progress Report contains a review of the research which has been done over the first half (1992 and 1993 to date) of the current three-year DOE grant, plus some earlier research to establish a broader perspective of the research interests. High energy physics research at Duke has three components. The first, Task A, is based upon experiments carried out at Fermilab`s Tevatron Collider. The group is finishing the analysis of data from their first collider experiment (E735), a study of inclusive particle production from {bar p} p collisions at {radical}{bar s} = 1.8 TeV. The second component of the research, Task B, deals primarily with heavy flavor physics. The third part of the research program, Task D, deals with preparation for research at the SSC. The authors have been active in the development of tracking detectors for the SSC since 1989, and are now concentrating on the design and construction of straw tube drift chambers for the solenoid detector.
Date: March 1, 1993
Creator: Fortney, L.R.; Goshaw, A.T. & Walker, W.D.
Partner: UNT Libraries Government Documents Department

Meson production in relativistic heavy-ion collisions at AGS energies

Description: Single particle inclusive spectra are presented for pion and kaon production in Si + Au reactions at an incident momentum of 14.6 A [center dot] GeV/c and Au + Au reactions at an incident momentum of 11.6 A [center dot] GeV/c. A simple geometric scaling of the pion production for central collisions as A[sub proj][sup 1/3] and A[sub targ][sup 2/3] results from the observed production of about one pion per participant. Kaon yields are shown to be proportional to the number of excited participants and consistent with RQMD and ARC calculations.
Date: January 1, 1993
Creator: Steadman, S. G. (Massachusetts Inst. of Tech., Cambridge, MA (United States). Lab. for Nuclear Science)
Partner: UNT Libraries Government Documents Department

SUSY searches at CDF

Description: A set of jet events with large amount of Missing E{sub Tau} from the Fermilab CDF experiment was analyses to search for SUSY signature. No significant signals were observed above the Standard Model background. Some effects of some SUSY parameters on the squark and gluino mass limits are presented.
Date: June 1, 1993
Creator: Hu, Ping & collaboration, CDF
Partner: UNT Libraries Government Documents Department

Meson production in relativistic heavy-ion collisions at AGS energies

Description: Single particle inclusive spectra are presented for pion and kaon production in Si+Au reactions at an incident momentum of 14.6 A {center_dot} GeV/c and Au+Au reactions at an incident momentum of 11.6 A {center_dot} GeV/c. A simple geometric scaling of the pion production for central collisions as A{sub proj}{sup 1/3} and A{sub targ}{sup 2/3} results from the observed production of about one pion per participant. Kaon yields are shown to be proportional to the number of excited participants and consistent with RQMD and ARC calculations.
Date: July 1, 1993
Creator: Steadman, S. G. & Collaboration, E802
Partner: UNT Libraries Government Documents Department

Electron identification in the PHENIX experiment using a tracking TRD

Description: Measuring dielectron physics signals at RHIC will require the ability to separate electrons from pions to a level of better than 2 {times} 10{sup {minus}4} over momenta ranging from 0.1 GeV/c to 5.0 GeV/c. Particle identification over this momentum range is realized in the PHENIX detector at RHIC by a combination of detector subsystems, one of which is a tracking TRD. The PHENIX tracking TRD allows electron-pion separation utilizing both TR and dE/dx information, while simultaneously tracking charged particles with good position accuracy. The electron-pion separation of this device is better than 3 {times} 10{sup {minus}3} for particles with momenta ranging from 250 MeV/c to over 10 GeV/c.
Date: November 1, 1993
Creator: O`Brien, E.; Bennett, M. & Cherniatin, V.
Partner: UNT Libraries Government Documents Department

Search for top quark with D0 detector

Description: We report preliminary results of a search for the top quark by the D{O} collaboration at the Fermilab Tevatron p{bar p} collider using a data sample corresponding to an integrated luminosity of about 7.5 pb{sup {minus}1}. Events with a high p{sub T} isolated electron and large missing E{sub T} which are candidates for containing W bosons were studied. Only one vent was found having an additional isolated lepton. Combining the ee and e{mu} channels we set a lower limit of 99 GeV/c{sup 2} for the top quark mass.
Date: September 1, 1993
Creator: Protopopescu, Serban D.
Partner: UNT Libraries Government Documents Department

Recent results on top, bottom and exotic physics at the Tevatron

Description: A summary of results from the recently concluded 1991--1993 Tevatron run is presented. Selected topics from b physics and exotic particle searches from the CDF and D0 collaborations are reviewed. Preliminary results from the CDF top search, using 12pb{sup {minus}1} from the 1992--1993 run, are given. In particular, the lepton + b-tag and dilepton analyses are discussed. Preliminary results from the CDF dilepton analysis places a lower limit on the top quark mass of 108GeV/c{sup 2} at the 95% C.L.
Date: August 1, 1993
Creator: Shaw, N. M.
Partner: UNT Libraries Government Documents Department

D{O} results on searches for the top quark

Description: We have performed a search for creation of the top quark in p{bar p} collisions at {radical}s = 1.8 GeV at Tevatron, Fermilab. t{bar t} production followed by top decay to W + b quark is assumed. We have searched for the decay channels with both W`s decaying leptonically, and with one W decay to an electron and the other to quarks. A preliminary report on the status of one interesting event is presented. By combining the results from the ee and e{mu} channels a lower top mass limit of 99 GeV on the 95% confidence level is obtained.
Date: September 1, 1993
Creator: Abachi, S.
Partner: UNT Libraries Government Documents Department

Signal and background in NLO QCD for the search of the intermediate mass Higgs boson at the SSC

Description: The signal and background for the search of the Standard Model Higgs boson in the intermediate mass range 80 GeV < m{sub H} < 2M{sub Z} is studied based on calculations of the cross sections in next-to-leading order QCD perturbation theory for the production of the Higgs boson via gluon-gluon fusion and for the hadronic two-photon production. The method of Monte-Carlo integration allows the application of realistic cuts (p{sub T}, rapidity, photon isolation) to the cross section. Results are given for the K-factors of the signal and the background. It turns out that the NLO corrections improve the situation for a Higgs boson mass in the range of 80--120 GeV. Furthermore, the influence of a cut on the transverse momentum of the additional jet produced in the processes gg {yields} Hg, gq {yields} Hq, q{bar q} {yields} Hg is compared to a similar cut for the background.
Date: August 15, 1993
Creator: Bailey, B. & Graudenz, D.
Partner: UNT Libraries Government Documents Department

Search for excited quarks in p{bar p} collisions at {radical}s = 1.8 TeV

Description: If quarks are composite particles then excited states are expected in p{bar p} collisions. Using the CDF detector we have searched for excited quarks (q*) which decay to common quarks by emitting a W boson (q* {yields} qW) or a photon (q* {yields} q-{gamma}). In the W + jet and photon + jet mass spectra we see no compelling evidence for a q* mass resonance. We set an upper limit on the q* cross section vs. mass, and using the simplest model of excited quark production, we exclude excited quarks in the mass range 90 < M* < 570 GeV at 95% confidence level. This analysis is preliminary and only statistical uncertainties have been included.
Date: August 1, 1993
Creator: Collaboration, CDF
Partner: UNT Libraries Government Documents Department

Top dilepton search at CDF

Description: The authors present preliminary results from a search for the top quark in the dilepton channel using data collected by CDF during the 1992--93 Fermilab Collider Run. The dilepton analysis implies a lower limit on the top quark mass of 113 GeV/c{sup 2} at the 95% confidence level, assuming Standard Model decays.
Date: August 1, 1993
Creator: Collaboration, The CDF
Partner: UNT Libraries Government Documents Department

Search for the Top Quark at D0

Description: We present preliminary results on the search for the top quark in p{bar p} collisions at {radical}s = 1.8 TeV by the D{O} collaboration at the Fermilab Tevatron. The data presented correspond to an integrated luminosity of about 7.5 pb{sup {minus}1}. We have conducted searches in the electron-muon (e{mu}) and the dielectronic (ee) top decay channels. One e{mu} event was found. We obtain a lower limit on the top mass of 99 GeV/c{sup 2} at 95% C.L.
Date: September 1993
Creator: Narain, Meenakshi & D0 Collaboration
Partner: UNT Libraries Government Documents Department

Searches for B hadrons at CDF

Description: The CDF data from the 1992--93 Tevatron run contains a large, clean sample of events which contain fully reconstructed J/{psi} {yields} {mu}{sup +}{mu}{sup {minus}}. This data has been employed in a search for B hadrons which contain J/{psi} amongst their decay products. An analysis of 8 pb{sup {minus}1} of data produces no evidence for {Lambda}{sub b} {yields} J/{psi}{Lambda}. A signal of 14.0 {plus_minus} 4.7 events is seen for the B{sub s} {yields} J/{psi}{phi}. The B{sub s} mass has been determined to be 5383.3 {plus_minus} 4.5 (stat) {plus_minus} 5.0 (syst.).
Date: September 1993
Creator: Lukens, Patrick T.
Partner: UNT Libraries Government Documents Department

Sparticle searches at CDF

Description: A set of jet events with large amount of Missing E{sub T} (E{sub t}) from the Fermilab CDF experiment was analysed to search SUSY signature. The absence of the signal resulted in squark and glunio mass limits (m{anti q} > 126 GeV/c{sup 2} and m{anti g} > 141 GeV/c{sup 2}). Some effects of some SUSY parameters on the squark and glunio mass limits are presented.
Date: January 1993
Creator: Hu, Ping & CDF Collaboration
Partner: UNT Libraries Government Documents Department

SUSY Searches at D0

Description: Searches for evidence of supersymmetric particles, and other phenomena beyond the Standard Model, are well underway with the D0 detector at the Tevatron. The D0 detector has good central tracking, excellent energy and missing E{sub T} resolution, hermetic calorimetry, and wide muon coverage. Preliminary results from searches for gluino/squark production and first generation leptoquark production are presented, based on a small fraction of the data taken to date.
Date: June 1993
Creator: Sawyer, Lee
Partner: UNT Libraries Government Documents Department