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University of Nebraska - Lincoln

2000

Kenneth Bloom Publications

Articles 1 - 23 of 23

Full-Text Articles in Physics

Measurement Of The Decay Amplitudes Of B0JK*0 And BS0J/Ψφ Decays, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Nov 2000

Measurement Of The Decay Amplitudes Of B0 → J/ΨK*0 And BS0 → J/Ψφ Decays, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

An angular analysis of B0JK*0and Bs0J/ψφ has been used to determine the decay amplitudes with parity-even longitudinal (A0) and transverse (A) polarization and parity-odd transverse (A) polarization. The measurements are based on 190 B0 and 40Bs0candidates obtained from 89 pb-1 of p̅p collisions at the Fermilab Tevatron. The longitudinal decay amplitude dominates with |A0|2= 0.59 ± 0.06 ± 0.01 for B0 and |A0|2 = 0.61 ± 0.14 ± 0.02 for Bs0 decays. The parity-odd ...


Dijet Production By Double Pomeron Exchange At The Fermilab Tevatron, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Nov 2000

Dijet Production By Double Pomeron Exchange At The Fermilab Tevatron, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report the first observation of dijet events with a double Pomeron exchange topology produced in p̅p collisions at √s= 1800 GeV. The events are characterized by a leading antiproton, two jets in the central pseudorapidity region, and a large rapidity gap on the outgoing proton side. We present results on jet kinematics and production rates, compare them with corresponding results from single diffractive and inclusive dijet production, and test factorization.


Direct Measurement Of The W Boson Width In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Oct 2000

Direct Measurement Of The W Boson Width In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

This Letter describes a direct measurement of the W boson total decay width, Γ W, using the Collider Detector at Fermilab. The measurement uses an integrated luminosity of 90 pb-1, collected during the 1994–1995 run of the Fermilab Tevatron pp̅ collider. The width is determined by normalizing predicted signal and background distributions to 49 844 W candidates and 21 806 Wμν candidates in the transverse-mass region MT < 200 GeV and then fitting the predicted shape to the 438 electron events and 196 muon events in the high-MT region, 100<MT < 200 GeV. The result is G Γ W= 2.04 ± 0.11(stat) ± 0.09(syst) GeV.


Measurement Of J/Ψ And Ψ(2s) Polarization In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Oct 2000

Measurement Of J/Ψ And Ψ(2s) Polarization In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have measured the polarization of J/ψ and ψ(2S) mesons produced in pp̅ collisions at √s= 1.8 TeV, using data collected at the Collider Detector at Fermilab during 1992–1995. The polarization of promptly produced J/ψ[ψ(2S)] mesons is isolated from those produced in B-hadron decay, and measured over the kinematic range 4 [5.5] < PT < 20 GeV/c and |y| < 0.6. For PT≥ 12 GeV/c we do not observe significant polarization in the prompt component.


Search For Second And Third Generation Leptoquarks Including Production Via Technicolor Interactions In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Sep 2000

Search For Second And Third Generation Leptoquarks Including Production Via Technicolor Interactions In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report the results of a search for second and third generation leptoquarks using 88 pb-1 of data recorded by the Collider Detector at Fermilab. Color triplet technipions, which play the role of scalar leptoquarks, are investigated due to their potential production in decays of strongly coupled color octet technirhos. Events with a signature of two heavy flavor jets and missing energy may indicate the decay of a second (third) generation leptoquark to a charm (bottom) quark and a neutrino. As the data are found to be consistent with standard model expectations, mass limits are determined.


Search For New Particles Decaying To Tt̅ In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Sep 2000

Search For New Particles Decaying To Tt̅ In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We use 106 pb-1 of data collected with the Collider Detector at Fermilab to search for narrow-width, vector particles decaying to a top and an antitop quark. Model independent upper limits on the cross section for narrow, vector resonances decaying to tt̅ are presented. At the 95% confidence level, we exclude the existence of a leptophobic Z′ boson in a model of top-color-assisted technicolor with mass MZ′ < 480 GeV/c2 for natural width Γ = 0.012MZ0 , and MZ′ < 780 GeV/c2 for Γ = MZ′ .


Limits On Light Gravitino Production And New Processes With Large Missing Transverse Energy In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Aug 2000

Limits On Light Gravitino Production And New Processes With Large Missing Transverse Energy In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

Events collected by the Collider Detector at Fermilab (CDF) with an energetic jet plus large missing transverse energy can be used to search for physics beyond the standard model. We see no deviations from the expected backgrounds and set upper limits on the production of new processes. We consider in addition the production of light gravitinos and set a limit at 95% confidence level on the breaking scale √F ≥ 217 GeV, which excludes gravitino masses smaller than 1.1 x 10-5 eV/c2.


Search For The Charged Higgs Boson In The Decays Of Top Quark Pairs In The EΤ And Μτ Channels At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jul 2000

Search For The Charged Higgs Boson In The Decays Of Top Quark Pairs In The EΤ And Μτ Channels At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

Top quark production offers the unique opportunity to search for a charged Higgs boson (H±), as the contribution from tH+b τ + νb can be large in extensions of the standard model. We use results from a search for top quark pair production by the Collider Detector at Fermilab (CDF) in the e τ +ET+jets and μ τ+ET+jets signatures to set an upper limit on the branching ratio of Ɓ (tH+b) in 106 pb-1 of data. The upper limit is in the range 0.5 to 0.6 at 95 ...


Search For Scalar Top And Scalar Bottom Quarks In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jun 2000

Search For Scalar Top And Scalar Bottom Quarks In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have searched for direct pair production of scalar top and scalar bottom quarks in 88 pb-1 of pp̅ collisions at √s =1.8 TeV with the CDF detector. We looked for events with a pair of heavy flavor jets and missing energy, consistent with scalar top (bottom) quark decays to a charm (bottom) quark and a neutralino. The numbers of events that pass our selections show no significant deviation from standard model expectations. We compare our results to the next-to-leading order scalar quark production cross sections to exclude regions in scalar quark-neutralino mass parameter space.


Search For A W′ Boson Via The Decay Mode W′→Μν Μ In 1.8 Tev Pp̅ Collisions, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jun 2000

Search For A W′ Boson Via The Decay Mode W′→Μν Μ In 1.8 Tev Pp̅ Collisions, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report the results of a search for a W′ boson produced in pp̅ collisions at a center-of-mass energy of 1.8 TeV using a 107 pb-1 data sample recorded by the Collider Detector at Fermilab. We consider the decay channel W′→ μνμ and search for anomalous production of high transverse mass μνμ lepton pairs. We observe no excess of events above background and set limits on the rate of W′ boson production and decay relative to standard model W boson production and decay using a fit of the transverse mass distribution observed. If we assume standard ...


Search For Scalar Top Quark Production In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jun 2000

Search For Scalar Top Quark Production In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have searched for direct production of scalar top quarks at the Collider Detector at Fermilab in 88 pb-1 of pp collisions at √s =1.8 TeV. We assume the scalar top quark decays into either a bottom quark and a chargino or a bottom quark, a lepton, and a scalar neutrino. The event signature for both decay scenarios is a lepton, missing transverse energy, and at least two b-quark jets. For a chargino mass of 90 GeV/c2 and scalar neutrino masses of at least 40 GeV/c2, we find no evidence for scalar top ...


System Architecture And Hardware Design Of The Cdf Xft Online Track Processor, S. Holm, J.R. Dittman, J. Freeman, R. Klein, J.D. Lewis, T.M. Shaw, T. Wesson, C. Ciobanu, J. Gerstenslager, J. Hoftiezer, R. Hughes, M. Johnson, P. Koehn, C. Neu, C. Sanchez, B.L. Winer, Kenneth A. Bloom, D. Gerdes, J.W. Dawson, W.N. Haberichter Jun 2000

System Architecture And Hardware Design Of The Cdf Xft Online Track Processor, S. Holm, J.R. Dittman, J. Freeman, R. Klein, J.D. Lewis, T.M. Shaw, T. Wesson, C. Ciobanu, J. Gerstenslager, J. Hoftiezer, R. Hughes, M. Johnson, P. Koehn, C. Neu, C. Sanchez, B.L. Winer, Kenneth A. Bloom, D. Gerdes, J.W. Dawson, W.N. Haberichter

Kenneth Bloom Publications

A trigger track processor is being designed for CDF Run 2. This processor identifies high momentum (PT > 1.5 GeV/c) charged tracks in the new central outer tracking chamber for the CDF I1 detector. The design of the track processor, called the extremely Fast Trackcr (XFT), is highly parallel and handle an input rate of 183 Gbitslsec and output rate of 44 Gbitdsec. The XFT is pipclined and reports the results for a new event every 132ns. The XFT uses threc stages, hit classification, segment finding, and segment linking. The pattem recognition algorithm for the three stages are ...


Diffractive Dijets With A Leading Antiproton In P̅P Collisions At √S = 1800 Gev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration May 2000

Diffractive Dijets With A Leading Antiproton In P̅P Collisions At √S = 1800 Gev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report results from a study of events with a leading antiproton of beam momentum fraction 0.905 <xF < 0.965 and 4-momentum transfer squared |t|< 3 GeV2 produced in p̅p collisions at √s =1800 GeV at the Fermilab Tevatron collider. Approximately 2% of the events contain two jets of transverse energy ETjet > 7 GeV. Using the dijet events, we evaluate the diffractive structure function of the antiproton and compare it with expectations based on results obtained in diffractive deep inelastic scattering experiments at the DESY ep collider HERA.


Measurement Of The Differential Dijet Mass Cross Section In Pp̅ Collisions At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration May 2000

Measurement Of The Differential Dijet Mass Cross Section In Pp̅ Collisions At √S =1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of the cross section for production of two or more jets as a function of dijet mass, based on an integrated luminosity of 86 pb-1 collected with the Collider Detector at Fermilab. Our dijet mass spectrum is described within errors by next-to-leading order QCD predictions using CTEQ4HJ parton distributions, and is in good agreement with a similar measurement from the DØ experiment.


Measurement Of Sin 2Β From BJKS0 With The Cdf Detector, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Apr 2000

Measurement Of Sin 2Β From B→J/ΨKS0 With The Cdf Detector, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

This paper reports an updated measurement of the standard model CP violation parameter sin 2β using the CDF Detector at Fermilab. The entire run I data sample of 110 pb-1 of proton-antiproton collisions at √s =1.8 TeV is used to identify a signal sample of ≈400 BJ/ ψKs0 events, where J/ψ→ μ+μ- and Ks0→ π+ π-. The flavor of the neutral B meson is identified at the time of production by combining information from three tagging algorithms: a same-side tag, a jet-charge tag, and a soft-lepton tag. A maximum likelihood ...


Production Of ϒ(1s) Mesons From ΧB Decays In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Mar 2000

Production Of ϒ(1s) Mesons From ΧB Decays In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have reconstructed the radiative decays χ b(1P) → Υ (1S) γ and χb(2P) → Υ (1S) γ in pp̅ collisions at √s = 1.8 TeV, and measured the fraction of Υ(1S) mesons that originate from these decays. For Υ(1S) mesons with pTY > 8.0 GeV/c, the fractions that come from χ b(1P) and χb(2P) decays are [27.1 ± 6.9(stat) ± 4.4(syst)]% and [10.5 ± 4.4(stat) ± 1.4(syst)]%, respectively. We have derived the fraction of directly produced Υ(1S) mesons to be [50.9 ± 8 ...


Measurement Of B-Quark Fragmentation Fractions In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Feb 2000

Measurement Of B-Quark Fragmentation Fractions In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We have studied the production of B hadrons in 1.8-TeV pp̅ collisions. We present measurements of the fragmentation fractions, fu, fd, fs, and fbaryon, of produced b quarks that yield B+, B0, Bs0, and Λ̅b0 hadrons. Reconstruction of five electron-charm final states yields fs/(fu+ fd)= 0.213 ± 0.068 and fbaryon/(fu+ fd)= 0.118 ± 0.042, assuming fu=fd. If all B hadrons produced in pp̅ collisions cascade to one of these four hadrons, we determine fu=fd ...


Search For Color Singlet Technicolor Particles In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Feb 2000

Search For Color Singlet Technicolor Particles In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We search for color singlet technirho and technipion production in pp̅ collisions at √s = 1.8 TeV recorded with the Collider Detector at Fermilab. These exotic technimesons are present in a model of walking technicolor. The signatures studied are lepton plus two jets plus E/T and multijet final states. No excess of events is seen in either final state. We set an upper limit on the technirho production cross section and exclude a region in the technipion mass versus technirho mass plane.


Measurement Of Bb̅ Rapidity Correlations In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Feb 2000

Measurement Of Bb̅ Rapidity Correlations In Pp̅ Collisions At √S =1.8 Tev, F. Abe, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report the first direct measurement of bb̅ rapidity correlations in pp̅ collisions at √s =1.8 TeV. We select events with a high transverse momentum muon accompanied by a jet, and a second jet associated with a decay vertex displaced from the pp̅ interaction vertex. Two independent samples are obtained corresponding to events with a forward (2.0<|η|bb̅ production to be 0.361±0.033(stat) -0.031+0.015(syst), in good agreement with the next-to-leading order QCD prediction 0.338-0.097+0.014


Transverse Momentum And Total Cross Section Of E+E- Pairs In The Z-Boson Region, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jan 2000

Transverse Momentum And Total Cross Section Of E+E- Pairs In The Z-Boson Region, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

The transverse momentum and total cross section of e+e- pairs in the Z-boson region of 66 < Mee < 116 GeV/c2 from pp̅ collisions at √s =1.8 TeV are measured using 110 pb-1 of collisions taken by the Collider Detector at Fermilab during 1992–1995. The total cross section is measured to be 248 ± 11 pb. The differential transverse momentum cross section is compared with calculations that match quantum chromodynamics perturbation theory at high transverse momentum with the gluon resummation formalism at low transverse momentum.


Search For A Fourth-Generation Quark More Massive Than The Z0 Boson In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jan 2000

Search For A Fourth-Generation Quark More Massive Than The Z0 Boson In Pp̅ Collisions At √S = 1.8 Tev, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present the results of a search for pair production of a fourth-generation charge -⅓ quark (b′) in √s =1.8 TeV pp collisions using 88 pb-1 of data obtained with the Collider Detector at Fermilab. We assume that both quarks decay via the flavor-changing neutral current process b′bZ0 and that the b′ mass is greater than mz+ mb. We studied the decay mode b′b̅′Z0Z0 bb̅ where one Z0 decays into e+e- or μ+μ-and the other decays hadronically, giving a signature of two leptons plus jets ...


Observation Of Diffractive B-Quark Production At The Fermilab Tevatron, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jan 2000

Observation Of Diffractive B-Quark Production At The Fermilab Tevatron, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We report a measurement of the fraction of b quarks produced diffractively in p̅p collisions at √s =1.8 TeV. Diffraction is identified by the absence of particles in a forward pseudorapidity region. From events with an electron of transverse momentum 9.5< pTe /c within the pseudorapidity region |η| < 1.1, the ratio of diffractive to total b-quark production rates is found to be Rbb= [0.62 ± 0.19(stat) ± 0.16(syst)]%. This result is comparable in magnitude to corresponding ratios for W and dijet production but significantly lower than expectations based on factorization.


Measurement Of The Helicity Of W Bosons In Top Quark Decays, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Jan 2000

Measurement Of The Helicity Of W Bosons In Top Quark Decays, T. Affolder, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We use the transverse momentum spectrum of leptons in the decay chain tbW with W to measure the helicity of the W bosons in the top quark rest frame. Our measurement uses a tt̅ sample isolated in 106 ± 4 pb-1 of data collected in pp̅ collisions at √s = 1.8 TeV with the CDF detector at the Fermilab Tevatron. Assuming a standard V-A weak decay, we find that the fraction of W’s with zero helicity in the top rest frame is F0 = 0.91 ± 0.37(stat)± 0.13(syst), consistent with the standard model ...