572 research outputs found
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The search for single top quark production in the muon plus jets channel at D0
No full textThe authors have performed a search for the electroweak production of single top quarks in p{bar p} collisions at the Fermilab Tevatron at a center of mass energy of {radical}s = 1.96 TeV. The search was performed in the muon plus jets decay channel requiring at least one b-tagged jet. The data were collected using the D0 detector between August 2002 and September 2003 corresponding to an integrated luminosity of 158 pb{sup -1}. The resulting 95% C.L. upper limits on the production cross sections are 27 pb in the s-channel, 41 pb in the t-channel, and 36 pb in the combined s + t channel using the secondary vertex tagger (SVT) algorithm. They also present results from the combined electron and muon channel search using the D0 detector
Search for associated Higgs boson production WH -> WWW*-> l(+/-)nu l('+/-)nu(')+X in p(p)over-bar collisions at root S=1.96 TeV
No full textWe present a search for associated Higgs boson production in the process p (p) over bar -> WH -> WWW*-> l(+/-)nu l('+/-)nu(')+X in final states containing two like-sign isolated electrons or muons (e(+/-)e(+/-), e(+/-)mu(+/-), or mu(+/-)mu(+/-)). The search is based on D0 run II data samples corresponding to integrated luminosities of 360-380 pb(-1). No excess is observed over the predicted standard model background. We set 95% C.L. upper limits on sigma ->(p (p) over bar WH) x Br(H -> WW*) between 3.2 and 2.8 pb for Higgs boson masses from 115 to 175 GeV
Analysis of the Vector Boson Self Interaction and the Search for Anomalous Couplings at Center-of-Mass Energy = 1.8 TeV Proton-Antiproton Collisions
No full text222 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 2001.The production cross section times decay branching ratios for W + g and Z/DY + g have been measured in s = 1.8 TeV p¯p collisions using muon and electron data samples obtained during the 1992--1993 and 1994--1995 collider runs at the Fermilab Tevatron with the CDF detector corresponding to a total integrated luminosity of 110 pb-1. For photons with transverse energy EgT > 7.0 GeV, pseudo-rapidity in the central or plug region (|eta l| 0.7, we observed 122(213) muon(electron) Wg candidates and 36(43) muon(electron) Z/DYg candidates. We observe a total of 335 muon plus electron W + g and 79 muon plus electron Z/DY + g candidates, whereas the standard model expectation is 264.6 +/- 18.2 W + g events and 74.2 +/- 4.2 Z/DY + g events. The combined electron plus muon channel results correspond to sigma · B(W + g ) = 19.8 +/- 1.7 pb and sigma · B( Z/DY + g ) = 5.5 +/- 0.8 pb. The next-to-leading-order standard model predictions are sigma · B(W + g ) = 14.8 pb and sigma · B(Z/ DY + g ) = 5.8 pb. For W + g this corresponds to a ∼35% excess relative to the standard model prediction.U of I OnlyRestricted to the U of I community idenfinitely during batch ingest of legacy ETD
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The Stimulus test stand
No full textThe Stimulus Test Stand was originally constructed and assembled for testing the SVX2 ASIC readout and then upgraded for SVX3 ASIC prototyping and testing. We have modified this system for SVX4 ASIC [1] prototype testing. We described the individual components below. Additional details for other hardware for SVX4 testing can be found in reference [2]. We provide a description of the Stimulus Test Stand used for prototype testing of the SVX4 chip
Production of WZ events in pp(-) collisions at root s=1.96 TeV and limits on anomalous WWZ couplings
No full textWe present results from a search for WZ production with subsequent decay to l nu l'(l) over bar'(l and l' = e or mu) using 0.30 fb(-1) of data collected by the D0 experiment between 2002 and 2004 at the Fermilab Tevatron. Three events with WZ decay characteristics are observed. With an estimated background of 0.71 +/- 0.08 events, we measure the WZ production cross section to be 4.5(-2.6)(+3.8) pb, with a 95% C.L. upper limit of 13.3 pb. The 95% C.L. limits for anomalous WWZ couplings are found to be -2.0 <Delta kappa(Z)< 2.4 for form factor scale Lambda=1 TeV, and -0.48 <lambda(Z)< 0.48 and -0.49 <Delta g(1)(Z)< 0.66 for Lambda=1.5 TeV
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Preliminary test results for the SVX4
No full textWe present and summarize the preliminary test results for SVX4 chip testing. There are presently two versions of the SVX4. Version 2 has on-chip bypassing and Version 1 does not. The on-chip bypassing is a layer of transistors under the front-end analog pipeline that acts as a bypassing capacitor for the voltage supply. Its size is about a microfarad. We aggressively choose to test Version 2 because of this feature. The feature is advantageous for hybrid design because it eliminates the need for an additional passive component on the hybrid itself by placing it on the actual SVX4 die. Also, the SVX4 was designed to operate in two modes: D. and CDF. One can set which mode the chip will operate by placing a jumper in the proper position on the SVX4 chip carrier. In either mode, the chip can either use the operating parameters from the shift register or the shadow register. Similarly, this is selected by placing a jumper on the SVX4 chip carrier. This chip has this feature because it was unknown whether the new design of the shadow register would be operable. The shadow register is also call the SEU register or Single Event Upset register. An introduction into the functionality of the chip and an explanation on the difference between D. and CDF mode can be found in the SVX4 User's Manual [1]
Search for randall-sundrum gravitons in dilepton and diphoton final states
No full textWe report the first direct search for the Kaluza-Klein (KK) modes of Randall-Sundrum gravitons using dielectron, dimuon, and diphoton events observed with the D0 detector operating at the Fermilab Tevatron p (p) over bar Collider at root s = 1: 96 TeV. No evidence for resonant production of gravitons has been found in the data corresponding to an integrated luminosity of approximate to 260 pb(-1). Lower limits on the mass of the first KK mode at the 95% C. L. have been set between 250 and 785 GeV, depending on its coupling to standard model particles
Search for doubly charged Higgs boson pair production in the decay to mu(+)mu(+)mu(-)mu(-) in p(p)over-bar collisions at root s=1.96 TeV
No full textA search for pair production of doubly charged Higgs bosons in the process p (p) over bar -->H++H---->mu(+)mu(+)mu(-)mu(-) is performed with the D0 run II detector at the Fermilab Tevatron. The analysis is based on a sample of inclusive dimuon data collected at an energy of roots=1.96 TeV, corresponding to an integrated luminosity of 113 pb(-1). In the absence of a signal, 95% confidence level mass limits of M(H-L(+/-+/-))>118.4 GeV/c(2) and M(H-R(+/-+/-))>98.2 GeV/c(2) are set for left-handed and right-handed doubly charged Higgs bosons, respectively, assuming 100% branching into muon pairs
Search for large extra spatial dimensions in dimuon production with the D0 detector
No full textWe present the results of a search for the effects of large extra spatial dimensions in p (p) over bar collisions at root s = 1: 96 TeV in events containing a pair of energetic muons. The data correspond to 246 pb(-1) of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron Collider. Good agreement with the expected background was found, yielding no evidence for large extra dimensions. We set 95% C. L. lower limits on the fundamental Planck scale between 0.85 and 1.27 TeV within several formalisms. These are the most stringent limits achieved in the dimuon channel to date
Measurement of the Lambda(b)(0) lifetime using Lambda(b)(0)->Lambda(c)(+)l(-)(nu)over-bar
No full textThe lifetime of Lambda(b)(0) is measured using the semileptonic decay Lambda(b)(0)-->Lambda(c)(+)l(-)nu(-), where the Lambda(c)(+) is reconstructed through its decay Lambda(c)(+) --> pK(-)pi(+). The data were collected by the CDF detector at the Tevatron Collider during 1992-1995 and correspond to an integrated luminosity of 110 pb(-1) of collisions at root s=1.8 TeV. From a fit to the decay length distribution of the Lambda(c)-lepton system from 197+/-25 signal events, the lifetime of Lambda(b)(0) is measured to be 1.32+/-0.15+/- 0.07 ps
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