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Model-Independent Global Search for New High-pT Physics at CDF

Description: Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with respect to the standard model prediction. A model-independent approach (Vista) considers the gross features of the data, and is sensitive to new large cross section physics. A quasi-model-independent approach (Sleuth) searches for a significant excess of events with large summed transverse momentum, and is particularly sensitive to new electroweak scale physics that appears predominantly in one final state. This global search for new physics in over three hundred exclusive final states in 927 pb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV reveals no such significant indication of physics beyond the standard model.
Date: December 1, 2007
Creator: CDF Collaboration
Partner: UNT Libraries Government Documents Department

First Flavor-Tagged Determination of Bounds on Mixing-Induced CP Violation in B^0_s --> j/psi phi Decays

Description: This Letter describes the first determination 1 of bounds on the CP-violation parameter 2{beta}{sub s} using B{sub s}{sup 0} decays in which the flavor of the bottom meson at production is identified. The result is based on approximately 2, 000 B{sub s}{sup 0} {yields} J/{psi}{phi} decays reconstructed in a 1.35 fb{sup -1} data sample collected with the CDFII detector using p{bar p} collisions produced at the Fermilab Tevatron. We report confidence regions in the two-dimensional space of 2{beta}{sub s} and the decay-width difference {Delta}{Lambda}. Assuming the standard model predictions of 2{beta}{sub s} and {Delta}{Lambda}, the probability of a deviation as large as the level of the observed data is 15%, corresponding to 1.5 Gaussian standard deviations.
Date: December 1, 2007
Creator: CDF Collaboration
Partner: UNT Libraries Government Documents Department

A Measurement of the Top Quark Mass in 1.96 TeV Proton-Antiproton Collisions Using a Novel Matrix Element Method

Description: A measurement of the top quark mass in t{bar t} {yields} l + jets candidate events, obtained from p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron using the CDF II detector, is presented. The measurement approach is that of a matrix element method. For each candidate event, a two dimensional likelihood is calculated in the top pole mass and a constant scale factor, 'JES', where JES multiplies the input particle jet momenta and is designed to account for the systematic uncertainty of the jet momentum reconstruction. As with all matrix element techniques, the method involves an integration using the Standard Model matrix element for t{bar t} production and decay. However, the technique presented is unique in that the matrix element is modified to compensate for kinematic assumptions which are made to reduce computation time. Background events are dealt with through use of an event observable which distinguishes signal from background, as well as through a cut on the value of an event's maximum likelihood. Results are based on a 955 pb{sup -1} data sample, using events with a high-p{sub T} lepton and exactly four high-energy jets, at least one of which is tagged as coming from a b quark; 149 events pass all the selection requirements. They find M{sub meas} = 169.8 {+-} 2.3(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.
Date: September 30, 2007
Creator: CDF Collaboration
Partner: UNT Libraries Government Documents Department

Search for Bs --> mu+mu- and Bd --> mu+mu- Decays with 2fb-1 of ppbar Collisions

Description: The authors have performed a search for B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -} and B{sup 0} {yields} {mu}{sup +}{mu}{sup -} decays in p{bar p} collisions at {radical}s = 1.96 TeV using 2 fb{sup -1} of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron Collider. The observed number of B{sub s}{sup 0} and B{sup 0} candidates is consistent with background expectations. The resulting upper limits on the branching fractions are {Beta}(B{sub s}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 5.8 x 10{sup -8} and {Beta}(B{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 1.8 x 10{sup -8} at 95% C.L.
Date: December 1, 2007
Creator: CDF Collaboration
Partner: UNT Libraries Government Documents Department

First Measurement of the Fraction of Top Quark Pair Production Through Gluon-Gluon Fusion

Description: We present the first measurement of {sigma}(gG {yields} t{bar t})/{sigma}(p{bar p} {yields} t{bar t}). We use 0.96 fb{sup -1} of {radical}s = 1.96 TeV p{bar p} collision data recorded with the CDF II detector at Fermilab. We identify the candidate t{bar t} events with a high-energy charged lepton, a neutrino candidate, and four or more jets with at least one identified as originating from a b quark. Using charged particles with low transverse momentum in t{bar t} events, we find {sigma}(gg {yields} t{bar t})/{sigma}(p{bar p} {yields} t{bar t}) = 0.07 {+-} 0.14(stat) {+-} 0.07(syst), in agreement with the standard model NLO prediction of 0.15 {+-} 0.05.
Date: December 1, 2007
Creator: CDF Collaboration
Partner: UNT Libraries Government Documents Department

Fully reconstructed B-meson decays using J/{psi} and {psi}(2S)

Description: In this paper we present CDF B-meson branching ratio results involving color-suppressed {ital B} {r_arrow} {Psi}{Kappa} decays, where {Psi} = {ital J}/{psi}, {psi}(2{ital S}) and {Kappa} = {Kappa}, {Kappa}{sup *}. Fully reconstructed decays of {ital B} {r_arrow} {ital J}/{psi}{Kappa}, {ital B} {r_arrow} {psi}(2{ital S}){Kappa}, {ital B}{sup +} {r_arrow} {ital J}/{psi}{pi}{sup +} and {ital B}{sub s} {r_arrow} {ital J}/{psi}{phi} are used to extract branching ratios, vector-pseudoscalar ratios and polarization parameters.
Date: September 1, 1996
Creator: Miao, Ting
Partner: UNT Libraries Government Documents Department

Quarks and gluons at hadron colliders

Description: Data from proton-antiproton collisions at high energy provide important information on constraining the quark and gluon distributions in the nucleon and place limits on quark substructure. The S asymmetry data constrains the slope of the d/u quark distributions and significantly reduces the systematic error on the extracted value of the W mass. Drell-Yan data at high invariant mass provides strong limits on quark substructure. Information on {alpha}{sub s} and the gluon distributions can be extracted from high P{sub T} jet data and direct photons.
Date: August 1, 1996
Creator: Bodek, A.
Partner: UNT Libraries Government Documents Department

CDF top physics

Description: The authors present the latest results about top physics obtained by the CDF experiment at the Fermilab Tevatron collider. The data sample used for these analysis (about 110 pb{sup {minus}1}) represents almost the entire statistics collected by CDF during four years (1992--95) of data taking. This large data size has allowed detailed studies of top production and decay properties. The results discussed here include the determination of the top quark mass, the measurement of the production cross section, the study of the kinematics of the top events and a look at top decays.
Date: May 1, 1996
Creator: Tartarelli, G. F.
Partner: UNT Libraries Government Documents Department

Top quark results at CDF

Description: We present the latest results on the top quark obtained by the CDF experiment using a data sample of about 110 {ital pb}{sup -1} collected at the Fermilab Tevatron collider. We briefly describe the candidate events selection and then discuss the production cross section determination and the mass measurement. The study of two new decay channels (all hadronic and ``tau dilepton``) is also reported.
Date: August 1, 1996
Creator: Leone, S.
Partner: UNT Libraries Government Documents Department

Quarkonia production at CDF

Description: In the 1992-1995 runs CDF has collected large samples of {ital J/{psi}}, {psi}(2{ital S}) and {Gamma} identified through their muonic decay. In the charmonium system all production sources have been separately measured and compared with the theoretical predictions. A large excess of direct production has been observed for both {psi}(s{ital S}) and {ital J/{psi}}. the relative production rate for the {chi}{sub c}{sup 1} and {chi}{sub c}{sup 2} has also been measured. The unexpected results have lead to a profound revisitation of the theory of the production of {ital Q{anti Q}} bound states in high energy hadronic collisions.
Date: August 1, 1996
Creator: Sansoni, A.
Partner: UNT Libraries Government Documents Department

Electroweak physics at CDF

Description: The CDF collaboration is engaged in a broad program of electroweak measurements. The production of WW, WZ, ZZ, W{sub {gamma}}, Z{sub {gamma}} and the high mass Drell Yan charge asymmetry will be discussed, along with a status report on extracting a new W mass from the most recent 90 pb{sup {minus}1} data sample.
Date: June 1, 1996
Creator: Nodulman, L.
Partner: UNT Libraries Government Documents Department

Double boson production at CDF

Description: New measurements of boson pair production in {ital p}{ital {anti p}} collisions have been performed by the CDF collaboration using a data sample of approximately 110 pb{sup -1}. The cross sections for WW and WZ production are measured in the pure leptonic decay channel to {sigma}({ital p}{ital {anti p}} {r_arrow} WZ) = 3.2{sup +5.0}{sub -3. 2} pb and {sigma}({ital p}{ital {anti p}} {r_arrow} W{sup +}W{sup -}) = 10.2{sup +6.5}{sub -5.3} pb, respectively. Limits on anomalous coupling parameters are set in the searches for WW and WZ production. Assuming an energy scale of {Lambda}{sub FF} = 2 TeV, we find for the WWZ and WW{gamma} couplings at 95% CL: -0.4 {lt} {lambda} {lt} 0.3 ({delta}{kappa} = 0) and -0.5 {lt} {delta}{kappa} {lt} 0.5 ({lambda} = 0).
Date: July 1, 1996
Creator: Neuberger, D.
Partner: UNT Libraries Government Documents Department

W and Z boson plus jets production at CDF

Description: We have studied the production properties of {ital W} and {ital Z} bosons at CDF, and have measured the jet multiplicity cross sections and various kinematic distributions. We find good agreement with leading order QCD predictions with added gluon radiation and simulated parton fragmentation.
Date: September 1, 1996
Creator: Phillips, T. J.
Partner: UNT Libraries Government Documents Department

Overview of kinematic variables in top production

Description: A selection of simple kinematic variables chosen to be sensitive to different aspects of {ital t{anti t}} production in W + {>=} 3 jets events are studied. Monte Carlo comparisons are made between different top generators (Herwig, Pythia, and Isajet) and a QCD background generator (VECBOS). Finally, Monte Carlo predictions with the {ital t{anti t}} fraction constrained by the SVX {ital b}-tagging rate and measured top mass are compared with 110 pb{sup -1} of CDF data. We conclude that the CDF data is consistent with standard predictions using the studied generators.
Date: September 1, 1996
Creator: Binkley, M. & Beretvas, A.
Partner: UNT Libraries Government Documents Department

Time dependent B{sup 0} {anti B}{sup 0} mixing at CDF

Description: WE describe two measurements of {Delta}{ital m}{sub d}. The first uses {ital B} {r_arrow} {ital vlD}{sup (*)} events and a same-side flavor tagging algorithm. the second uses dilepton events. From the average of these two measurements we find {Delta}{ital m}{sub d} = 0. 466 {+-}0.037{+-} 0.031 ps{sup -1}.
Date: November 1, 1996
Creator: CDF Collaboration
Partner: UNT Libraries Government Documents Department

High E{sub T} jet cross sections at CDF

Description: The inclusive jet cross section for {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV as measured by the CDF collaboration will be presented. Preliminary CDF measurements of the {Sigma} E{sub T} cross section at {radical}s = 1.8 TeV and the central inclusive jet cross section at {radical}s = 0.630 TeV will also be shown.
Date: August 1, 1996
Creator: Flaugher, B.
Partner: UNT Libraries Government Documents Department

Top production at CDF

Description: We present the measurements of t{anti t} production cross section using {ital L} = 110 {ital pb{sup -1}} data sample of {ital p{anti p}} collisions at {radical}s = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). Combining the results from the channels with at least one W decaying into leptons ({ital e} or {mu}) plus jets we measure {sigma}{sub t{anti t}} = 7.5 {sup +1.9}{sub -1.6} {ital pb}. We report the observation of t{anti t} production in all hadronic decay channels using a kinematical selection and b identification techniques. Finally we show preliminary evidence for t {anti t} production in the decay mode with one e or {mu} in the final state and a hadronically decaying {tau}.
Date: May 1, 1996
Creator: Azzi, P.
Partner: UNT Libraries Government Documents Department

Top mass measurement at CDF

Description: We present the measurement of the top quark mass using L = 110 pb{sup -1} data sample of p{ovr p} collisions at {radical}s = 1.8 TeV collected with the Collider Detector at Fermilab (CDF). We show the results for the different channels and discuss with some emphasis the determination of the systematic uncertainties. 7 refs., 10 figs., 5 tabs.
Date: June 1, 1996
Creator: Rolli, S.
Partner: UNT Libraries Government Documents Department

Search for Centauro events at CDF

Description: A search was performed for centauro events in CDF minimum bias data. Within each event particles are detected and identified as wither hadronic requiring {ital E}{sub T} {gt} 0.4 GeV, or electromagnetic requiring {ital E}{sub T} {gt} 0.2 GeV, using calorimeter towers out to {vert_bar}{eta}{vert_bar} {lt} 4.2. The search for centauro like events is based primarily on their unique particle kinematics: particle multiplicities {approx} 75, mean {ital p{sub T}} {approx} 1. 7, and {eta} {approx} 2. In addition we look for centauro candidates with unusual hadronic and electromagnetic symmetry.
Date: July 1, 1996
Creator: Melese, P. L.
Partner: UNT Libraries Government Documents Department

Measurement of the average lifetime of B-hadrons produced in p{bar p} collisions at {radical}s = 1.8 TeV

Description: The average b-hadron lifetime has been measured using a high statistics sample of {ital B} {r_arrow} {ital J}/{psi}{Chi} decays recorded with the Collider Detector at Fermilab. We use a sample with an integrated luminosity of {approx} 90 {ital pb}{sup -1} recorded during the 1994-95 running period. The decay vertices of {approx} 62656 inclusive {ital J}/{psi} {r_arrow} {mu}{sup +}{mu}{sup -} candidates have been reconstructed using information from a silicon vertex-detector. The measured {ital B}lifetime, which is the average over all b-hadrons produced in {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV weighted by their branching ratios into {ital J}/{psi}, is 1.524 {+-} 0.015 ({ital stat}){sup +0.035}{sub -0.026} ({ital sys}) ps. The precision of this measurement is significantly improved compared to the inclusive lifetime measurement published previously using {approx} 10 {ital pb}{sup -1}.
Date: August 1, 1996
Creator: Wenzel, H.
Partner: UNT Libraries Government Documents Department

Diffractive dijet search with Roman pots at CDF

Description: We present the results of a search for diffractive dijets produced in {ital p}{ital {anti p}} collisions at {radical}s = 1.8 TeV from data collected by the Collider Detector at Fermilab using a Roman pot trigger. The dijet events exhibit additional diffractive characteristics such as rapidity gaps and boosted center-of-mass systems.
Date: August 1, 1996
Creator: Melese, P. L.
Partner: UNT Libraries Government Documents Department

Recent CDF results

Description: Preliminary results form the CDF detector, based on analysis of data collected in Run 1a and Run 1b at the Tevatron, totaling 110 pb{sup - 1} integrated luminosity, place new limits on the masses and couplings of new particles including charged Higgs bosons, supersymmetric gauge particles and quarks, and new vector bosons. One of the observed events, having an {ital e}{sup +}{ital e}{sup -} pair, two photons, and large missing energy would not occur with significant rate in the Standard Model, leading to speculation regarding its origin and the possible existence of related events.
Date: July 1, 1996
Creator: Conway, J. S.
Partner: UNT Libraries Government Documents Department