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First Measurement of the b-jet Cross Section in Events with a W Boson in p anti-p Collisions at s**(1/2) = 1.96-TeV

Description: The cross section for jets from b quarks produced simultaneously with a W boson has been measured in p{bar p} collision data from 1.9 fb{sup -1} of integrated luminosity recorded by the CDF II detector at the Tevatron. Jets consistent with the decay of long-lived hadrons are selected by identifying a displaced decay vertex. The invariant mass of the charged particle tracks associated with the vertex is sensitive to the flavor of the decaying hadron and is used to determine the fraction of jets from b-quark production. We measure a b-jet cross section of 2.74 {+-} 0.27(stat.) {+-} 0.42(syst.) pb in association with one flavor of leptonic W boson decay over a limited kinematic phase space.
Date: September 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Search for W and Z bosons in the reaction anti-p p ---> 2 jets + gamma at s**(1/2) = 1.8-TeV

Description: The authors present a study of the dijet invariant mass distribution for the reaction {bar p}p {yields} 2 jets+{gamma} + X, at a center of mass energy of 1.8 TeV, using data collected by the CDF experiment. They compare the data to predictions for the production of a photon with two jets, together with the resonant processes {bar p}p {yields} W/Z + {gamma} + X, in which the W and Z bosons decay hadronically. A fit is made to the dijet invariant mass distribution combining the non-resonant background and resonant processes. They use the result to establish a limit for the inclusive production cross section of W/Z + {gamma} with hadronic decay of the W and Z bosons.
Date: July 1, 2005
Creator: Acosta, D.; Affolder, Anthony A.; Albrow, M. G.; Ambrose, D.; Amidei, D.; Anikeev, K. et al.
Partner: UNT Libraries Government Documents Department

Updated Search for the Flavor-Changing Neutral-Current Decay $D^0 \to \mu^+ \mu^-$

Description: We report on a search for the flavor-changing neutral-current decay D{sup 0} {yields} {mu}{sup +}{mu}{sup -} in p{bar p} collisions at {radical}s = 1.96TeV using 360 pb{sup -1} of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. A displaced vertex trigger selects long-lived D{sup 0} candidates in the {mu}{sup +}{mu}{sup -}, {pi}{sup +}{pi}{sup -}, and K{sup -}{pi}{sup +} decay modes. We use the Cabibbo-favored D{sup 0} {yields} K{sup -}{pi}{sup +} channel to optimize the selection criteria in an unbiased manner, and the kinematically similar D{sup 0} {yields} {pi}{sup +}{pi}{sup -} channel for normalization. We set an upper limit on the branching fraction {Beta}(D{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 2.1 x 10{sup -7} (3.0 x 10{sup -7}) at the 90% (95%) confidence level.
Date: August 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Diffractive W and Z Production at the Fermilab Tevatron

Description: We report on a measurement of the fraction of events with a W or Z boson produced diffractively in {bar p}p collisions at {radical}s = 1.96 TeV, using data from 0.6 fb{sup -1} of integrated luminosity collected with the CDF II detector equipped with a Roman-pot spectrometer that detects the {bar p} from {bar p} + p {yields} {bar p}+[X+W/Z]. We find that (0.97 {+-} 0.11)% of Ws and (0.85 {+-} 0.22)% of Zs are produced diffractively in a region of (anti)proton fractional momentum loss {zeta} of 0.03 < {zeta} < 0.10 and 4-momentum transferred squared t of -1 < t < 0 (GeV/c){sup 2}. We also report on searches for W and Z production in double Pomeron exchange, p+{bar p} {yields} p+[X+W/z]+{bar p}, and on exclusive Z production, {bar p}p {yields} {bar p}+Z+p. No signal is seen above background for these processes, and comparisons are made with expectations.
Date: July 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Improved Search for a Higgs Boson Produced in Association with Z->l+l- in proton antiproton Collisions at sqrt(s) = 1.96 TeV

Description: We present a search for the standard model Higgs boson produced with a Z boson in 4.1 fb{sup -1} of data collected with the CDF II detector at the Tevatron. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electrons or muons, we set 95% credibility level upper limits on the ZH production cross section times the H {yields} b{bar b} branching ratio. Improved analysis methods enhance signal sensitivity by 20% relative to previous searches beyond the gain due to the larger data sample. At a Higgs boson mass of 115 GeV/c{sup 2} we set a limit of 5.9 times the standard model value.
Date: September 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

A Direct Top-Quark Width Measurement from Lepton + Jets Events at CDF II

Description: We present a measurement of the top-quark width using t{bar t} events produced in p{bar p} collisions at Fermilab's Tevatron collider and collected by the CDF II detector. In the mode where the top quark decays to a W boson and a bottom quark, we select events in which one W decays leptonically and the other hadronically (lepton + jets channel) . From a data sample corresponding to 4.3 fb{sup -1} of integrated luminosity, we identify 756 candidate events. The top-quark mass and the mass of W boson that decays hadronically are reconstructed for each event and compared with templates of different top-quark widths ({Lambda}{sub t}) and deviations from nominal jet energy scale ({Delta}{sub JES}) to perform a simultaneous fit for both parameters, where {Delta}{sub JES} is used for the in situ calibration of the jet energy scale. By applying a Feldman-Cousins approach, we establish an upper limit at 95% confidence level (CL) of {Lambda}{sub t} < 7.6 GeV and a two-sided 68% CL interval of 0.3 GeV < {Lambda}{sub t} < 4.4 GeV for a top-quark mass of 172.5 GeV/c{sup 2}, which are consistant with the standard model prediction. This is the first direct measurement of {Lambda}{sub t} to set a lower limit with 68% CL.
Date: August 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Exclusion of an Exotic Top Quark with -4/3 Electric Charge Using Soft Lepton Tagging

Description: We present a measurement of the electric charge of the top quark using p{bar p} collisions corresponding to an integrated luminosity of 2.7 fb{sup -1} at the CDF II detector. We reconstruct t{bar t} events in the lepton+jets final state and use kinematic information to determine which b-jet is associated with the leptonically- or hadronically-decaying t-quark. Soft lepton taggers are used to determine the b-jet flavor. Along with the charge of the W boson decay lepton, this information permits the reconstruction of the top quark's electric charge. Out of 45 reconstructed events with 2.4 {+-} 0.8 expected background events, 29 are reconstructed as tt with the standard model +2/3 charge, whereas 16 are reconstructed as t{bar t} with an exotic -4/3 charge. This is consistent with the standard model and excludes the exotic scenario at 95% confidence level. This is the strongest exclusion of the exotic charge scenario and the first to use soft leptons for this purpose.
Date: June 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of et al.
Partner: UNT Libraries Government Documents Department

First Measurement of the Ratio sigma_(t-tbar) / sigma_(Z/\gamma*->ll) and Precise Extraction of the t-tbar Cross Section

Description: We report a measurement of the ratio of the t{bar t} to Z/{gamma}* production cross sections in {radical}s = 1.96 TeV p{bar p} collisions using data corresponding to an integrated luminosity of up to 4.6 fb{sup -1}, collected by the CDF II detector. The t{bar t} cross section ratio is measured using two complementary methods, a b-jet tagging measurement and a topological approach. By multiplying the ratios by the well-known theoretical Z/{gamma}* {yields} ll cross section predicted by the standard model, the extracted t{bar t} cross sections are effectively insensitive to the uncertainty on luminosity. A best linear unbiased estimate is used to combine both measurements with the result {sigma}{sub t{bar t}} = 7.70 {+-} 0.52 pb, for a top-quark mass of 172.5 GeV/c{sup 2}.
Date: April 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of et al.
Partner: UNT Libraries Government Documents Department

Measurement of the $t\bar{t}$ Production Cross Section with an in situ Calibration of $b$-jet Identification Efficiency

Description: A measurement of the top-quark pair-production cross section in p{bar p} collisions at {radical}s = 1.96 TeV using data corresponding to an integrated luminosity of 1.12 fb{sup -1} collected with the Collider Detector at Fermilab is presented. Decays of top-quark pairs into the final states e{nu} + jets and {mu}{nu} + jets are selected, and the cross section and the b-jet identification efficiency are determined using a new measurement technique which requires that the measured cross sections with exactly one and multiple identified b-quarks from the top-quark decays agree. Assuming a top-quark mass of 175 GeV/c{sup 2}, a cross section of 8.5 {+-} 0.6(stat.) {+-} 0.7(syst.) pb is measured.
Date: July 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Measurement of the $WW+WZ$ Production Cross Section Using a Matrix Element Technique in Lepton + Jets Events

Description: We present a measurement of the WW + WZ production cross section observed in a final state consisting of an identified electron or muon, two jets, and missing transverse energy. The measurement is carried out in a data sample corresponding to up to 4.6 fb{sup -1} of integrated luminosity at {radical}s = 1.96 TeV collected by the CDF II detector. Matrix element calculations are used to separate the diboson signal from the large backgrounds. The WW + WZ cross section is measured to be 17.4 {+-} 3.3 pb, in agreement with standard model predictions. A fit to the dijet invariant mass spectrum yields a compatible cross section measurement.
Date: August 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Search for the supersymmetric partner of the top quark in ppbar collisions at sqrt(s) = 1.96 TeV

Description: We present a search for the lightest supersymmetric partner of the top quark in proton-antiproton collisions at a center-of-mass energy {radical}s = 1.96 TeV. This search was conducted within the framework of the R-parity conserving minimal supersymmetric extension of the standard model, assuming the stop decays dominantly to a lepton, a sneutrino, and a bottom quark. We searched for events with two oppositely-charged leptons, at least one jet, and missing transverse energy in a data sample corresponding to an integrated luminosity of 1 fb{sup -1} collected by the CDF experiment. No significant evidence of a stop quark signal was found. Exclusion limits at 95% confidence level in the stop quark versus sneutrino mass plane are set. Stop quark masses up to 180 GeV/c{sup 2} are excluded for sneutrino masses around 45 GeV/c{sup 2}, and sneutrino masses up to 116 GeV/c{sup 2} are excluded for stop quark masses around 150 GeV/c{sup 2}.
Date: September 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Oviedo U. /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Study of multi-muon events produced in p anti-p interactions at s**(1/2) = 1.96-TeV

Description: We report the results of a study of multi-muon events produced at the Fermilab Tevatron collider and acquired with the CDF II detector using a dedicated dimuon trigger. The production cross section and kinematics of events in which both muon candidates are produced inside the beam pipe of radius 1.5 cm are successfully modeled by known processes which include heavy flavor production. In contrast, we are presently unable to fully account for the number and properties of the remaining events, in which at least one muon candidate is produced outside of the beam pipe, in terms of the same understanding of the CDF II detector, trigger, and event reconstruction.
Date: June 12, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of et al.
Partner: UNT Libraries Government Documents Department

Search for the Production of Scalar Bottom Quarks in $p \bar {p} $ collisions at $\sqrt{s} $ = 1.96 TeV

Description: We report on a search for direct scalar bottom quark (sbottom) pair production in p{bar p} collisions at {radical}s = 1.96 TeV, in events with large missing transverse energy and two jets of hadrons in the final state, where at least one of the jets is required to be identified as originating from a b quark. The study uses a CDF Run II data sample corresponding to 2.65 fb{sup -1} of integrated luminosity. The data are in agreement with the standard model. In an R-parity conserving minimal supersymmetric scenario, and assuming that the sbottom decays exclusively into a bottom quark and a neutralino, 95% confidence-level upper limits on the sbottom pair production cross section of 0.1 pb are obtained. For neutralino masses below 70 GeV/c{sup 2}, sbottom masses up to 230 GeV/c{sup 2} are excluded at 95% confidence level.
Date: May 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of et al.
Partner: UNT Libraries Government Documents Department

Measurement of the $B^-$ lifetime using a simulation free approach for trigger bias correction

Description: The collection of a large number of B hadron decays to hadronic final states at the CDF II detector is possible due to the presence of a trigger that selects events based on track impact parameters. However, the nature of the selection requirements of the trigger introduces a large bias in the observed proper decay time distribution. A lifetime measurement must correct for this bias and the conventional approach has been to use a Monte Carlo simulation. The leading sources of systematic uncertainty in the conventional approach are due to differences between the data and the Monte Carlo simulation. In this paper they present an analytic method for bias correction without using simulation, thereby removing any uncertainty between data and simulation. This method is presented in the form of a measurement of the lifetime of the B{sup -} using the mode B{sup -} {yields} D{sup 0}{pi}{sup -}. The B{sup -} lifetime is measured as {tau}{sub B{sup -}} = 1.663 {+-} 0.023 {+-} 0.015 ps, where the first uncertainty is statistical and the second systematic. This new method results in a smaller systematic uncertainty in comparison to methods that use simulation to correct for the trigger bias.
Date: April 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of et al.
Partner: UNT Libraries Government Documents Department

Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and \textit{in situ} Jet Energy Calibration

Description: A precision measurement of the top quark mass m{sub t} is obtained using a sample of t{bar t} events from p{bar p} collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m{sub t} and a parameter {Delta}{sub JES} used to calibrate the jet energy scale in situ. Using a total of 1087 events, a value of m{sub t} = 173.0 {+-} 1.2 GeV/c{sup 2} is measured.
Date: October 1, 2010
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of; Amerio, S.; /INFN, Padua et al.
Partner: UNT Libraries Government Documents Department

Implementation of the shower max electron trigger at CDF

Description: The authors have built and installed new electronics which brings the central shower max detector into the CDF Level-2 trigger. By matching a stiff track from the central fast track processor to an associated shower max cluster, this trigger improvement reduces the electron Level-2 cross section by approximately 50% while retaining greater than 85% of real electrons and allows the authors to lower their electron trigger threshold.
Date: June 1, 1994
Creator: Byrum, K.; Dawson, J.; Nodulman, L.; Wicklund, A.B.; Amidei, D.; Burkett, K. et al.
Partner: UNT Libraries Government Documents Department

Search for second-generation scalar leptoquarks in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: Results on a search for pair production of second generation scalar leptoquark in p{bar p} collisions at {radical}s=1.96 TeV are reported. The data analyzed were collected by the CDF detector during the 2002-2003 Tevatron Run II and correspond to an integrated luminosity of 198 pb{sup -1}. Leptoquarks (LQ) are sought through their decay into (charged) leptons and quarks, with final state signatures represented by two muons and jets and one muon, large transverse missing energy and jets. We observe no evidence for LQ production and derive 95% C.L. upper limits on the LQ production cross sections as well as lower limits on their mass as a function of {beta}, where {beta} is the branching fraction for LQ {yields} {mu}q.
Date: December 1, 2005
Creator: Abulencia, A.; Acosta, D.; Adelman, J.; Affolder, Anthony A.; Akimoto, T.; Albrow, M.G. et al.
Partner: UNT Libraries Government Documents Department

Construction of the CDF silicon vertex detector

Description: Technical details and methods used in constructing the CDF silicon vertex detector are presented. This description includes a discussion of the foam-carbon fiber composite structure used to silicon microstrip detectors and the procedure for achievement of 5 {mu}m detector alignment. The construction of the beryllium barrel structure, which houses the detector assemblies, is also described. In addition, the 10 {mu}m placement accuracy of the detectors in the barrel structure is discussed and the detector cooling and mounting systems are described. 12 refs.
Date: April 1, 1992
Creator: Skarha, J.; Barnett, B.; Boswell, C.; Snider, F.; Spies, A.; Tseng, J. et al.
Partner: UNT Libraries Government Documents Department

Operation of the CDF Silicon Vertex Detector with colliding beams at Fermilab

Description: In this paper we briefly describe the main features of the CDF Silicon Vertex Detector (SVX) and discuss its performance during actual colliding beam operation at the Fermilab Tevatron. Details on S/N ratio, alignment, resolution and efficiency are given.
Date: October 1, 1992
Creator: Bedeschi, F.; Bolognesi, V.; Dell`Agnello, S.; Galeotti, S.; Grieco, G.; Mariotti, M. et al.
Partner: UNT Libraries Government Documents Department

Inclusive charged hadron and K{sup 0} production in two-photon interactions

Description: The analogous process to quark pair production in e{sup +} e{sup {minus}} annihilation is the hard-scattering quark exchange process in {gamma}{gamma} interactions. This hard-scattering process is expected to dominate the cross section at high transverse momenta of the produced quarks. Experimentally, one has looked for this process in two-jet as well as inclusive particle production and has found a relatively low PT onset of hard scattering in {gamma}{gamma} interactions. This report examines the issue in more detail (high statistics) for charged particle inclusive production and checks if the heavier flavors display a similar behavior in inclusive K{sup 0} production.
Date: March 1, 1988
Creator: Cords, D.; Boyer, J.; Butler, F.; Gidal, G.; Abrams, G. S.; Amidei, D. et al.
Partner: UNT Libraries Government Documents Department

Search for New Bottomlike Quark Pair Decays Q Q-Bar to (T W- ) (T-Bar W -) in Same-Charge Dilepton Events

Description: We report the most restrictive direct limits on masses of fourth-generation down-type quarks b{prime}, and quark-like composite fermions (B or T{sub 5/3}), decaying promptly to tW{sup {-+}}. We search for a significant excess of events with two same-charge leptons (e, {mu}), several hadronic jets, and missing transverse energy. An analysis of data from p{bar p} collisions with an integrated luminosity of 2.7 fb{sup -1} collected with the CDF II detector at Fermilab yields no evidence for such a signal, setting mass limits m{sub b{prime}}, m{sub B} > 338 GeV/c{sup 2} and m{sub T{sub 5/3}} > 365 GeV/c{sup 2} at 95% confidence level.
Date: April 2, 2012
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Alvarez Gonzalez, B.; Phys., /Cantabria Inst. of et al.
Partner: UNT Libraries Government Documents Department

An integral field spectrograph for SNAP supernova studies

Description: A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment. The goal is to ensure proper identification of Type Ia supernovae and to standardize the magnitude of each candidate by determining explosion parameters. An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented in this paper. The spectrograph concept is optimized to have very high efficiency and low spectral resolution (R {approx} 100), constant through the wavelength range (0.35-1.7{micro}m), adapted to the scientific goals of the mission.
Date: July 29, 2002
Creator: Ealet, Anne; Prieto, E.; Bonissent, A.; Malina, R.; Basa, S.; LeFevre, O. et al.
Partner: UNT Libraries Government Documents Department