Showing papers by "D. P. Benjamin published in 2004"
TL;DR: In this paper, a joint analysis of the direct W boson mass and width measurements is presented, along with the combined results of the measured W and Z boson leptonic partial cross sections.
Abstract: The results based on 1992–95 data (Run 1) from the CDF and D0 experiments on the measurements of the W boson mass and width are presented, along with the combined results. We report a Tevatron collider average MW = 80.456±0.059 GeV. We also report the Tevatron collider average of the directly measured W boson width GammaW = 2.115±0.105 GeV. We describe a new joint analysis of the direct W mass and width measurements. Assuming the validity of the standard model, we combine the directly measured W boson width with the width extracted from the ratio of W and Z boson leptonic partial cross sections. This combined result for the Tevatron is GammaW = 2.135±0.050 GeV. Finally, we use the measurements of the direct total W width and the leptonic branching ratio to extract the leptonic partial width Gamma(W-->enu) = 224±13 MeV.
71 citations
TL;DR: In this article, the decay mechanisms of Bs0 → μ +μ- and Bd0 → Bn 0 → μ+μ- in pp collisions were investigated, and four variables were used such as invariant mass of muon pair, B-candidate proper decay length, opening angle between B-hadron flight direction and Bcandidate track isolation, and a blind analysis technique was also used for determination of optimal selection criteria for four variables.
Abstract: The decay mechanisms of Bs0 → μ +μ- and Bd0 → μ +μ- in pp collisions were investigated. For discrimination of the decays from background events, four variables were used such as invariant mass of muon pair, B-candidate proper decay length, opening angle between B-hadron flight direction and B-candidate track isolation. A 'blind' analysis technique was also used for determination of optimal selection criteria for four variables. The results show that optimal set of selection criteria uses ∓80 MeV/c2 search window around B s0 mass, and I > 0.65.
67 citations
TL;DR: The results of a search for doubly-charged Higgs bosons decaying to dileptons using ~240/pb of ppbar collision data collected by the CDF II experiment at the Fermilab Tevatron were presented in this paper.
Abstract: We present the results of a search for doubly-charged Higgs bosons (H+/-+/-) decaying to dileptons using ~240/pb of ppbar collision data collected by the CDF II experiment at the Fermilab Tevatron. In our search region, given by same-sign dilepton mass m_ll' > 80 GeV/c^2 (100 GeV/c^2 for dielectron channel), we observe no evidence for doubly-charged Higgs production. We set limits on sigma (ppbar --> H++H-- --> l+l+l-l-) as a function of the mass of the doubly-charged Higgs boson and the chirality of its couplings. Assuming exclusive same-sign dilepton decays, we derive lower mass limits on H+/-+/-_L of 133 GeV/c^2, 136 GeV/c^2, and 115 GeV/c^2 in the ee, mu mu, and e mu channels, respectively, and a lower mass limit of 113 GeV/c^2 on H+/-+/-_R in the mu mu channel, all at the 95% confidence level.
63 citations
TL;DR: In this article, the authors measured the ambient charged track momentum in events containing large transverse energy jets at { radical}(s)=1800 GeV and {radical}(S)=630 GeV, and compared this ambient momentum with that observed both in minimum bias events and with that predicted by two Monte Carlo models.
Abstract: For comparison of inclusive jet cross sections measured at hadron-hadron colliders to next-to-leading order (NLO) parton-level calculations, the energy deposited in the jet cone by spectator parton interactions must first be subtracted. The assumption made at the Tevatron is that the spectator parton interaction energy is similar to the ambient level measured in minimum bias events. In this paper, we test this assumption by measuring the ambient charged track momentum in events containing large transverse energy jets at {radical}(s)=1800 GeV and {radical}(s)=630 GeV and comparing this ambient momentum with that observed both in minimum bias events and with that predicted by two Monte Carlo models. Two cones in {eta}-{phi} space are defined, at the same pseudorapidity, {eta}, as the jet with the highest transverse energy (E{sub T}{sup (1)}), and at {+-}90{sup o} in the azimuthal direction, {phi}. The total charged track momentum inside each of the two cones is measured. The minimum momentum in the two cones is almost independent of E{sub T}{sup (1)} and is similar to the momentum observed in minimum bias events, whereas the maximum momentum increases roughly linearly with the jet E{sub T}{sup (1)} over most of the measured range. This study was carried out usingmore » data from the CDF detector taken during Run 1 (1994-1995). The study will help improve the precision of comparisons of jet cross section data and NLO perturbative QCD predictions. The distribution of the sum of the track momenta in the two cones is also examined for five different E{sub T}{sup (1)} bins. The HERWIG and PYTHIA Monte Carlo generators are reasonably successful in describing the data, but neither can describe completely all of the event properties.« less
54 citations
TL;DR: In this paper, a measurement of the t (t) over bar production cross section using dilepton events with jets and missing transverse energy in p (p) was reported.
Abstract: We report a measurement of the t (t) over bar production cross section using dilepton events with jets and missing transverse energy in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV. Using a 197+/-12 pb(-1) data sample recorded by the upgraded Collider Detector at Fermilab, we use two complementary techniques to select candidate events. We compare the number of observed events and selected kinematical distributions with the predictions of the standard model and find good agreement. The combined result of the two techniques yields a t (t) over bar production cross section of 7.0(-2.1)(+2.4)(stat)(-1.1)(+1.6)(syst)+/-0.4(lum) pb.
39 citations
TL;DR: In this article, the isolated direct photon cross section in pp collisions at {radical}(s)= 1.8 TeV and |eta|< 0.9 using data collected between 1994 and 1995 by the Collider Detector at Fermilab (CDF).
Abstract: We present a measurement of the isolated direct photon cross section in pp collisions at {radical}(s)=1.8 TeV and |{eta}|<0.9 using data collected between 1994 and 1995 by the Collider Detector at Fermilab (CDF). The measurement is based on events where the photon converts into an electron-positron pair in the material of the inner detector, resulting in a two track event signature. To remove {pi}{sup 0}{yields}{gamma}{gamma} and {eta}{yields}{gamma}{gamma} events from the data we use a new background subtraction technique which takes advantage of the tracking information available in a photon conversion event. We find that the shape of the cross section as a function of photon p{sub T} is poorly described by next-to-leading-order QCD predictions, but agrees with previous CDF measurements.
34 citations
11 Apr 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The Transition Radiation Tracker (TRT) as discussed by the authors provides a combination of continuous tracking with many projective measurements based on individual drift-tubes (or straws) and of electron identification based on radiator fibres or foils interleaved between the straws themselves.
Abstract: The ATLAS Inner Detector consists of three sub-systems, the Pixel Detector at the innermost radius, the Semi-Conductor Tracker at intermediate radii, and the Transition Radiation Tracker (TRT) at the outermost radius in front of the electromagnetic calorimeter. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift-tubes (or straws) and of electron identification based on radiator fibres or foils interleaved between the straws themselves. This paper describes the current status of design and construction of the various components of the TRT: the assembly of the barrel modules has recently been completed, that of the end-cap wheels is well underway, and the on-detector front-end electronics is in production. The detector modules and front-end electronics boards will be integrated together over the next year, the barrel and end-cap TRT parts will be assembled and tested with their SCT counterparts during 2005 and installation and commissioning in the ATLAS pit will take place at the end of 2005 and the beginning of 2006. (C) 2004 Elsevier B.V. All rights reserved. (Less)
33 citations
TL;DR: In this paper, a neural network was used to search for standard model single-top-quark production in the 106 pb(-1) dataset accumulated by the Collider Detector at Fermilab detector during the 1992-1995 collider run (''run I'').
Abstract: We use a neural-network technique to search for standard model single-top-quark production in the 106 pb(-1) dataset accumulated by the Collider Detector at Fermilab detector during the 1992-1995 collider run (''run I''). Using a sample of 64 W+1, 2, 3 jets events, we set a 95 percent confidence level upper limit of 24 pb on the W-gluon and W-* combined single-top cross section.
28 citations
TL;DR: It is reported on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb(-1) of ppmacr; collisions at sqrt[s]=1.8 TeV, recorded by the Collider Detector at Fermilab, and the final state of large missing transverse energy and one or two high energy jets is investigated.
Abstract: We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 pb(-1) of p (p) over bar collisions at roots=1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a (3+1+n)-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for n=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.
26 citations
TL;DR: It is found that the differential production cross section agrees in shape with predictions based on Regge theory and factorization, and that the ratio of double-Pomeron exchange to single diffractive production rates is relatively unsuppressed as compared to the O(10) suppression factor previously measured in single Diffractive production.
Abstract: The double-Pomeron exchange (DPE) process p + p → p′ + X + Y is investigated, where Y is a proton. The ratio of the number of DPE events in the region to the total number of events in the sample was 0.194±0.001±0.012. It was found that the value was lower than the prediction based on Regge factorization by a factor of 1.9 ± 0.2. It was indicated that the formation of a second rapidity gap in a single diffractive (SD) event is relatively unsuppressed. It was observed that the results favor those in which the Regge based shapes of the SD and DPE distributions remain unchanged and only the overall normalization is suppressed.
20 citations
11 Apr 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, the ATLAS Transition Radiation Tracker (TRT) performance depends critically on the choice of the active gas and on its properties, and the most important operational aspects which have led to the final choice of active gas for the operation of the TRT at the LHC design luminosity, are presented.
Abstract: The ATLAS Transition Radiation Tracker (TRT) performance depends critically on the choice of the active gas and on its properties. The most important operational aspects, which have led to the final choice of the active gas for the operation of the TRT at the LHC design luminosity, are presented. The TRT performance expected at these conditions is reviewed, including pile-up effects at high luminosity.
TL;DR: In this paper, the number of like-sign and opposite-sign lepton pairs arising from double semileptonic decays of b and b-flavoured hadrons was measured at the Fermilab Tevatron collider.
Abstract: We have measured the number of like-sign (LS) and opposite-sign (OS) lepton pairs arising from double semileptonic decays of b and $\overline{b}$ hadrons, pair produced at the Fermilab Tevatron collider. The data samples were collected with the Collider Detector at Fermilab during the 1992--1995 collider run by triggering on the existence of $\ensuremath{\mu}\ensuremath{\mu}$ or $e\ensuremath{\mu}$ candidates in an event. The observed ratio of LS to OS dileptons leads to a measurement of the average time-integrated mixing probability of all produced b-flavored hadrons which decay weakly, $\overline{\ensuremath{\chi}}=0.152\ifmmode\pm\else\textpm\fi{}0.007(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.011(\mathrm{syst}),$ that is significantly larger than the world average $\overline{\ensuremath{\chi}}=0.118\ifmmode\pm\else\textpm\fi{}0.005.$
11 Apr 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this paper, the transition radiation tracker for the ATLAS experiment at the LHC has been built and tested at the CERN SPS accelerator and the results from detailed studies of the straw-tube hit registration efficiency and drift-time measurements and of the pion and electron spectra without and with radiators are presented.
Abstract: Several prototypes of the Transition Radiation Tracker for the ATLAS experiment at the LHC have been built and tested at the CERN SPS accelerator. Results from detailed studies of the straw-tube hit registration efficiency and drift-time measurements and of the pion and electron spectra without and with radiators are presented.
TL;DR: In this article, a measurement of the polar-angle distribution of leptons from W boson decay, as a function of the W transverse momentum, is presented, using an 80+/-4 pb(-1) sample of p (p) over bar collisions at roots=1.8 TeV collected by the CDF detector and includes data from both the W-->e+nu and W-->mu+nu decay channels.
Abstract: We present a measurement of the polar-angle distribution of leptons from W boson decay, as a function of the W transverse momentum. The measurement uses an 80+/-4 pb(-1) sample of p (p) over bar collisions at roots=1.8 TeV collected by the CDF detector and includes data from both the W-->e+nu and W-->mu+nu decay channels. We fit the W boson transverse mass distribution to a set of templates from a Monte Carlo event generator and detector simulation in several ranges of the W transverse momentum. The measurement agrees with the standard model expectation, whereby the ratio of longitudinally to transversely polarized W bosons, in the Collins-Soper W rest frame, increases with the W transverse momentum at a rate of approximately 15% per 10 GeV/c.
University of Tsukuba1, United States Department of Energy2, University of Padua3, Johns Hopkins University4, Duke University5, Purdue University6, University of New Mexico7, University of Bologna8, University of California, Davis9, University of Illinois at Urbana–Champaign10, Lawrence Berkeley National Laboratory11, Carnegie Mellon University12, Okayama University13, Academia Sinica14, Osaka City University15
01 Feb 2004-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The Run IIb system as discussed by the authors uses single-sided sensors arranged in a compact structure, called a stave, with integrated readout and cooling systems for high luminosity running.
Abstract: Fermilab plans to deliver 5-15 fb{sup -1} of integrated luminosity to the CDF and D0 experiments. The current inner silicon detectors at CDF (SVXIIa and L00) will not tolerate the radiation dose associated with high luminosity running and will need to be replaced. A new readout chip (SVX4) has been designed in radiation-hard 0.25 {micro}m CMOS technology. Single sided sensors are arranged in a compact structure, called a stave, with integrated readout and cooling systems. This paper describes the general design of the Run IIb system, testing results of prototype electrical components (staves), and prototype silicon sensor performance before and after irradiation.
University of Tsukuba1, University of Padua2, Johns Hopkins University3, Duke University4, Purdue University5, Fermilab6, University of California, Davis7, University of Illinois at Urbana–Champaign8, Lawrence Berkeley National Laboratory9, Carnegie Mellon University10, University of California, Santa Barbara11, Wayne State University12, Seoul National University13, Okayama University14, Kyungpook National University15, Helsinki Institute of Physics16, Sungkyunkwan University17, Osaka City University18, University of Bologna19
TL;DR: In this article, the authors proposed a new detector for the Fermilab Run IIb Silicon Vertex Detector (SVXIIb), which is a radiation-tolerant replacement for the currently installed SVXII.
Abstract: The various generations of Silicon Vertex Detectors (SVX, SVX', SVXII) for Collider Detector at Fermilab (CDF) at the Fermilab Tevatron have been fundamental tools for heavy-flavor tagging via secondary vertex detection. The CDF Run IIb Silicon Vertex Detector (SVXIIb) has been designed to be a radiation-tolerant replacement for the currently installed SVXII because SVXII was not expected to survive the Tevatron luminosity anticipated for Run IIb. One major change in the new design is the use of a single mechanical and electrical element throughout the array. This element, called a stave, carries six single-sided silicon sensors on each side and is built using carbon fiber skins with a high thermal conductivity on a foam core with a built-in cooling channel. A Kapton bus cable carries power, data and control signals underneath the silicon sensors on each side of the stave. Sensors are read out in pairs via a ceramic hybrid glued on one of the sensors and equipped with four SVX4 readout chips. This new design concept leads to a very compact mechanical and electrical unit, allowing streamlined production and ease of testing and installation. A description of the design and mechanical performance of the stave is given. Results on the electrical performance obtained using prototype staves are also presented.
TL;DR: The main building block and readout unit of the planned CDF Run IIb silicon detector is a "stave," a highly integrated mechanical, thermal, and electrical structure that is a copper-on-Kapton flexible cable that is placed directly below the silicon microstrip sensors.
Abstract: The main building block and readout unit of the planned CDF Run IIb silicon detector is a "stave," a highly integrated mechanical, thermal, and electrical structure. One of its characteristic features is a copper-on-Kapton flexible cable for power, high voltage, data transmission, and control signals that is placed directly below the silicon microstrip sensors. The dense packaging makes deadtime-less operation of the stave a challenge since coupling of bus cable activity into the silicon sensors must be suppressed efficiently. The stave design features relevant for deadtime-less operation are discussed. The electrical performance achieved with stave prototypes is presented.
TL;DR: In this paper, a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with p(T) gt 11 GeV/c using a 107 pb(-1) sample of 1.8 TeV p (p) over bar collisions collected by the CDF detector is reported.
Abstract: We report on a search for anomalous production of events with at least two charged, isolated, like-sign leptons, each with p(T) gt 11 GeV/c using a 107 pb(-1) sample of 1.8 TeV p (p) over bar collisions collected by the CDF detector. We define a signal region containing low background from standard model processes. To avoid bias, we fix the final cuts before examining the event yield in the signal region using control regions to test the Monte Carlo predictions. We observe no events in the signal region, consistent with an expectation of 0.63(-0.07)(+0.84) events. We present 95% confidence level limits on new physics processes in both a signature-based context as well as within a representative minimal supergravity (tanbeta=3) model.
University of Padua1, Johns Hopkins University2, Duke University3, Purdue University4, University of Liverpool5, University of Pisa6, Fermilab7, University of California, Davis8, University of Illinois at Urbana–Champaign9, Lawrence Berkeley National Laboratory10, Rutherford Appleton Laboratory11, Wayne State University12, University of California, Santa Barbara13, Okayama University14, Kyungpook National University15, Helsinki Institute of Physics16, Academia Sinica17, Sungkyunkwan University18, Osaka City University19, University of Bologna20, Seoul National University21
TL;DR: The innermost layer (L00) of the Run IIa silicon detector of CDF was planned to be replaced for the high luminosity Tevatron upgrade of Run IIb as mentioned in this paper.
Abstract: The innermost layer (L00) of the Run IIa silicon detector of CDF was planned to be replaced for the high luminosity Tevatron upgrade of Run IIb. This new silicon layer (L0) is designed to be a radiation tolerant replacement for the otherwise very similar L00 from Run IIa. The data are read out via long, fine-pitch, low-mass cables allowing the hybrids with the chips to sit at higher z(/spl sim/70 cm), outside of the tracking volume. The design and first results from the prototyping phase are presented. Special focus is placed on the amount and the structure of induced noise as well as signal-to-noise values.