Showing papers by "Barry Blumenfeld published in 2007"
TL;DR: In this article, the authors present a detailed analysis of the performance of the Large Hadron Collider (CMS) at 14 TeV and compare it with the state-of-the-art analytical tools.
Abstract: CMS is a general purpose experiment, designed to study the physics of pp collisions at 14 TeV at the Large Hadron Collider (LHC). It currently involves more than 2000 physicists from more than 150 institutes and 37 countries. The LHC will provide extraordinary opportunities for particle physics based on its unprecedented collision energy and luminosity when it begins operation in 2007. The principal aim of this report is to present the strategy of CMS to explore the rich physics programme offered by the LHC. This volume demonstrates the physics capability of the CMS experiment. The prime goals of CMS are to explore physics at the TeV scale and to study the mechanism of electroweak symmetry breaking--through the discovery of the Higgs particle or otherwise. To carry out this task, CMS must be prepared to search for new particles, such as the Higgs boson or supersymmetric partners of the Standard Model particles, from the start-up of the LHC since new physics at the TeV scale may manifest itself with modest data samples of the order of a few fb−1 or less. The analysis tools that have been developed are applied to study in great detail and with all the methodology of performing an analysis on CMS data specific benchmark processes upon which to gauge the performance of CMS. These processes cover several Higgs boson decay channels, the production and decay of new particles such as Z' and supersymmetric particles, Bs production and processes in heavy ion collisions. The simulation of these benchmark processes includes subtle effects such as possible detector miscalibration and misalignment. Besides these benchmark processes, the physics reach of CMS is studied for a large number of signatures arising in the Standard Model and also in theories beyond the Standard Model for integrated luminosities ranging from 1 fb−1 to 30 fb−1. The Standard Model processes include QCD, B-physics, diffraction, detailed studies of the top quark properties, and electroweak physics topics such as the W and Z0 boson properties. The production and decay of the Higgs particle is studied for many observable decays, and the precision with which the Higgs boson properties can be derived is determined. About ten different supersymmetry benchmark points are analysed using full simulation. The CMS discovery reach is evaluated in the SUSY parameter space covering a large variety of decay signatures. Furthermore, the discovery reach for a plethora of alternative models for new physics is explored, notably extra dimensions, new vector boson high mass states, little Higgs models, technicolour and others. Methods to discriminate between models have been investigated. This report is organized as follows. Chapter 1, the Introduction, describes the context of this document. Chapters 2-6 describe examples of full analyses, with photons, electrons, muons, jets, missing ET, B-mesons and τ's, and for quarkonia in heavy ion collisions. Chapters 7-15 describe the physics reach for Standard Model processes, Higgs discovery and searches for new physics beyond the Standard Model
973 citations
TL;DR: In this paper, the capabilities of the CERN Large Hadron Collider (LHC) experiment to explore the rich heavy-ion physics program offered by the LHC are presented, and the potential of the CMS experiment to carry out a series of representative Pb-Pb measurements.
Abstract: This report presents the capabilities of the CMS experiment to explore the rich heavy-ion physics programme offered by the CERN Large Hadron Collider (LHC). The collisions of lead nuclei at energies , will probe quark and gluon matter at unprecedented values of energy density. The prime goal of this research is to study the fundamental theory of the strong interaction ? Quantum Chromodynamics (QCD) ? in extreme conditions of temperature, density and parton momentum fraction (low-x).This report covers in detail the potential of CMS to carry out a series of representative Pb-Pb measurements. These include bulk observables, (charged hadron multiplicity, low pT inclusive hadron identified spectra and elliptic flow) which provide information on the collective properties of the system, as well as perturbative probes such as quarkonia, heavy-quarks, jets and high pT hadrons which yield tomographic information of the hottest and densest phases of the reaction.
361 citations
TL;DR: Constraints on spin, parity, and charge conjugation parity of the X(3872) particle are derived by comparing measured angular distributions of the decay products with predictions for different J(PC) hypotheses.
Abstract: The authors present an analysis of angular distributions and correlations of the X(3872) in the exclusive decay mode X(3872) {yields} J/{psi}{pi}{sup +}{pi}{sup -} with J/{psi} {yields} {mu}{sup +}{mu}{sup -}. They use 780 pb{sup -1} of data from p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. They derive constraints on spin, parity, and charge conjugation parity of the X(3872) by comparing measured angular distributions of the decay products with predictions for different J{sup PC} hypotheses. The assignments J{sup PC} = 1{sup ++} and 2{sup -+} are the only ones consistent with the data.
191 citations
TL;DR: In this paper, the authors measured the polarizations of J/psi and {psi}(2S) mesons as functions of their transverse momentum p{sub T} when they are produced promptly in the rapidity range |y| < 0.6 with p{ sub T} {ge} 5 GeV/c.
Abstract: The authors have measured the polarizations of J/{psi} and {psi}(2S) mesons as functions of their transverse momentum p{sub T} when they are produced promptly in the rapidity range |y| < 0.6 with p{sub T} {ge} 5 GeV/c. The analysis is performed using a data sample with an integrated luminosity of about 800 pb{sup -1} collected by the CDF II detector. For both vector mesons, they find that the polarizations become increasingly longitudinal as p{sub T} increases from 5 to 30 GeV/c. These results are compared to the predictions of non-relativistic quantum chromo-dynamics and other contemporary models. The polarizations of J/{psi} and {psi}(2S) mesons from B-hadron decays are also reported.
143 citations
TL;DR: In this paper, measurements of the inclusive jet production cross section as a function of the jet transverse momentum in p{bar p} collisions at {radical}s = 1.96 TeV, using the k{sub T} algorithm and a data sample corresponding to 1.0 fb{sup -1} collected with the Collider Detector at Fermilab in Run II.
Abstract: The authors report on measurements of the inclusive jet production cross section as a function of the jet transverse momentum in p{bar p} collisions at {radical}s = 1.96 TeV, using the k{sub T} algorithm and a data sample corresponding to 1.0 fb{sup -1} collected with the Collider Detector at Fermilab in Run II. The measurements are carried out in five different jet rapidity regions with |y{sup jet}| < 2.1 and transverse momentum in the range 54 < p{sub T}{sup jet} < 700 GeV/c. Next-to-leading order perturbative QCD predictions are in good agreement with the measured cross sections.
118 citations
TL;DR: In this article, the authors reported the first measurements of W and Z boson cross-sections times the corresponding leptonic branching ratios for collisions at TeV based on the decays of the W and z bosons into electrons and muons.
Abstract: We report the first measurements of inclusive W and Z boson cross-sections times the corresponding leptonic branching ratios for collisions at TeV based on the decays of the W and Z bosons into electrons and muons. The data were recorded with the CDF II detector at the Fermilab Tevatron and correspond to an integrated luminosity of 72.0 ± 4.3 pb−1. We test e-μ lepton universality in W decays by measuring the ratio of the W → μν to W → eν cross sections and determine a value of 0.991 ± 0.004(stat.) ± 0.011(syst.) for the ratio of W − l − ν couplings (gμ/ge). Since there is no sign of non-universality, we combine our cross-section measurements in the different lepton decay modes and obtain nb and pb for dilepton pairs in the mass range between 66 GeV/c2 and 116 GeV/c2. We compute the ratio R of the W → lν to Z → ll cross sections taking all correlations among channels into account and obtain R = 10.84 ± 0.15(stat.) ± 0.14(syst.) including a correction for the virtual photon exchange component in our measured γ*/Z → ll cross section. Based on the measured value of R, we extract values for the W leptonic branching ratio, Br(W → lν)= 0.1082 ± 0.0022; the total width of the W boson, Γ(W)= 2092 ± 42 MeV; and the ratio of W and Z boson total widths, Γ(W)/Γ(Z)= 0.838 ± 0.017. In addition, we use our extracted value of Γ(W) whose value depends on various electroweak parameters and certain CKM matrix elements to constrain the Vcs CKM matrix element, |Vcs| = 0.976 ± 0.030.
106 citations
TL;DR: In this article, the authors measured the time dependence of the ratio of decay rates for the rare decay D0->K+pi- to the Cabibbo-favored decay D 0->K-pi+.
Abstract: We measure the time dependence of the ratio of decay rates for the rare decay D0->K+pi- to the Cabibbo-favored decay D0->K-pi+. We use a signal of 12.7 x10^3 D0->K+pi decays with proper decay times between 0.75 and 10 mean D0 lifetimes. The data sample was recorded with the CDF II detector at the Fermilab Tevatron and corresponds to an integrated luminosity of 1.5 fb-1 of p-pbar collisions at sqrt(s) = 1.96 TeV. We search for D0-D0bar mixing and measure the mixing parameters to be Rd = (3.04 +/- 0.55) x10^{-3}, y' = (8.5 +/- 7.6) x10^{-3}, and x'^2 = (-0.12 +/- 0.35) x10^{-3}. We report Bayesian probability contours in the x'^2-y' plane and find that the data are inconsistent with the no-mixing hypothesis with a probability equivalent to 3.8 Gaussian standard deviations.
100 citations
TL;DR: The first observation of exclusive e(+)e(-) production in hadron-hadron collisions is presented, using pp[over] collision data at (square root) s = 1.96 TeV taken by the run II Collider Detector at Fermilab.
Abstract: We present the first observation of exclusive e{sup +}e{sup -} production in hadron-hadron collisions, using p{bar p} collision data at {radical}s = 1.96 TeV taken by the Run II Collider Detector at Fermilab, and corresponding to an integrated luminosity of 532 pb{sup -1}. We require the absence of any particle signatures in the detector except for an electron and a positron candidate, each with transverse energy E{sub T} > 5 GeV and pseudorapidity |{eta}| < 2. With these criteria, 16 events are observed compared to a background expectation of 1.9 {+-} 0.3 events. These events are consistent in cross section and properties with the QED process p{bar p} {yields} p + e{sup +}e{sup -} + {bar p} through two-photon exchange. The measured cross section is 1.6{sub -0.3}{sup +0.5}(stat) {+-} 0.3(syst) pb. This agrees with the theoretical prediction of 1.71 {+-} 0.01 pb.
94 citations
85 citations
TL;DR: The observation and measurement of the mass of the bottom, strange baryon Xi(b)- through the decay chain Xi( b)- -->J/psiXi-, and a signal is observed whose probability of arising from a background fluctuation is 6.6 x 10(-15), or 7.7 Gaussian standard deviations.
Abstract: We report the observation and measurement of the mass of the bottom, strange baryon {xi}{sub b}{sup -} through the decay chain {xi}{sub b}{sup -}{yields}J/{psi}{xi}{sup -}, where J/{psi}{yields}{mu}{sup +}{mu}{sup -}, {xi}{sup -}{yields}{lambda}{pi}{sup -}, and {lambda}{yields}p{pi}{sup -}. A signal is observed whose probability of arising from a background fluctuation is 6.6x10{sup -15}, or 7.7 Gaussian standard deviations. The {xi}{sub b}{sup -} mass is measured to be 5792.9{+-}2.5(stat) {+-}1.7(syst) MeV/c{sup 2}.
81 citations
TL;DR: In this paper, the authors reported an observation of new bottom baryons produced in proton-antiproton collisions at the Tevatron using 1.1 fb^{-1} of data collected by the CDF II detector.
Abstract: We report an observation of new bottom baryons produced in proton-antiproton collisions at the Tevatron. Using 1.1 fb^{-1} of data collected by the CDF II detector, we observe four \Lambda_b^0\pi^{\pm} resonances in the fully reconstructed decay mode \Lambda_b^0 \to \Lambda_c^+ \pi^-, where \Lambda_c^+ \to p K^- \pi^+. We interpret these states as the \Sigma_b^{(*)\pm} baryons and measure the following masses: m_{\Sigma_b^+} = 5807.8^{+2.0}_{-2.2}(stat.) \pm 1.7(syst.) MeV/c^2, m_{\Sigma_b^-} = 5815.2 \pm 1.0(stat.) \pm 1.7(syst.) MeV/c^2, and m(\Sigma_b^*) - m(\Sigma_b) = 21.2^{+2.0}_{-1.9}(stat.) ^{+0.4}_{-0.3}(syst.) MeV/c^2.
TL;DR: In this paper, the authors search for exclusive {gamma}{gamma} production in proton-antiproton collisions at {radical}(s)=1.96 TeV, using 532 pb{sup -1} of integrated luminosity taken by the run II Collider Detector at Fermilab.
Abstract: We have searched for exclusive {gamma}{gamma} production in proton-antiproton collisions at {radical}(s)=1.96 TeV, using 532 pb{sup -1} of integrated luminosity taken by the run II Collider Detector at Fermilab. The event signature requires two electromagnetic showers, each with transverse energy E{sub T}>5 GeV and pseudorapidity |{eta}| =}3 events is 1.7x10{sup -4}. An upper limit on the cross section of pp{yields}p+{gamma}{gamma}+p production is set at 410 fb with 95% confidence level.
TL;DR: In this article, the authors measured the ratio of cross section times branching fraction, {sigma {chi}c2}{beta}({chi}{sub c2} {yields} J/{psi}{gamma}) in 1.96 TeV.
Abstract: The authors measure the ratio of cross section times branching fraction, {sigma}{sub {chi}c2}{beta}({chi}{sub c2} {yields} J/{psi}{gamma})/{sigma}{sub {chi}c1}{beta}({chi}{sub c1} {yields} J/{psi}{gamma}), in 1.1 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV. This measurement covers the kinematic range p{sub T} (J/{psi}) > 4.0 GeV/c, |{eta}(J/{psi})| 1.0 GeV/c. For events due to prompt processes, they find R{sub p} = 0.395 {+-} 0.016(stat.) {+-} 0.015(sys.). This result represents a significant improvement in precision over previous measurements of prompt {chi}{sub c1,2} hadroproduction.
TL;DR: In this paper, the authors presented a new measurement of the B{sup +} meson differential cross section d{sigma}/dP{sub T} at {radical}s = 1960 GeV.
Abstract: The authors present a new measurement of the B{sup +} meson differential cross section d{sigma}/dP{sub T} at {radical}s = 1960 GeV. The data correspond to an integrated luminosity of 739 pb{sup -1} collected with the upgraded CDF detector (CDF II) at the Fermilab Tevatron collider. B{sup +} candidates are reconstructed through the decay B{sup +} {yields} J/{psi} K{sup +}, with J/{psi} {yields} {mu}{sup +}{mu}{sup -}. The integrated cross section for producing B{sup +} mesons with p{sub T} {ge} 6 GeV/c and |y| {le} 1 is measured to be 2.78 {+-} 0.24 {mu}b.
TL;DR: This is the most precise single measurement of the W-boson mass to date.
Abstract: We present a measurement of the W boson mass using 200 pb{sup -1} of data collected in p{bar p} collisions at {radical}s = 1.96 TeV by the CDF II detector at Run II of the Fermilab Tevatron. With a sample of 63964 W {yields} ev candidates and 51128 W W {yields} {mu}v candidates, we measure M{sub W} = (80413 {+-} 34{sub stat} {+-}34{sub syst} = 80413 {+-} 48) MeV/c{sup 2}. This is the most precise single measurement of the W boson mass to date.
TL;DR: The mass measurement is based on an event-by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state.
Abstract: We present a measurement of the top-quark mass M-top in the all-hadronic decay channel t (t) over bar -> W(+)bW(-)(b) over bar -> q(1)(q) over bar (2)bq(3)(q) over bar (4)(b) over bar. The analysis is performed using 310 pb(-1) of root s=1.96 TeV p (p) over bar collisions collected with the CDF II detector using a multijet trigger. The mass measurement is based on an event-by-event likelihood which depends on both the sample purity and the value of the top-quark mass, using 90 possible jet-to-parton assignments in the six-jet final state. The joint likelihood of 290 selected events yields a value of M-top=177.1 +/- 4.9(stat)+/- 4.7(syst) GeV/c(2).
TL;DR: In this paper, the authors reported a measurement of the top quark mass, M{sub t}, in the dilepton decay channel of t{bar t} {yields} b{ell}{prime}{sup +} {nu}{sub {ell}}, {bar b}{ell}{sup -}{bar {nu}}{sub { ell}} using an integrated luminosity of 1.0 fb{sup -1} of p{bar p} collisions collected with the CDF II detector.
Abstract: We report a measurement of the top quark mass, M{sub t}, in the dilepton decay channel of t{bar t} {yields} b{ell}{prime}{sup +} {nu}{sub {ell}}, {bar b}{ell}{sup -}{bar {nu}}{sub {ell}} using an integrated luminosity of 1.0 fb{sup -1} of p{bar p} collisions collected with the CDF II detector. We apply a method that convolutes a leading-order matrix element with detector resolution functions to form event-by-event likelihoods; we have enhanced the leading-order description to describe the effects of initial-state radiation. The joint likelihood is the product of the likelihoods from 78 candidate events in this sample, which yields a measurement of M{sub t} = 164.5 {+-} 3.9(stat.) {+-} 3.9(syst.) GeV/c{sup 2}, the most precise measurement of M{sub t} in the dilepton channel.
TL;DR: In this paper, a search for a narrow resonance in electron-positron events in the invariant mass range of 150-950 GeV/c{sup 2} using 1.3 fb{sup -1} of p{bar p} collision data at {radical}s=1.96 TeV collected by the CDF II detector at Fermilab was conducted.
Abstract: We report the results of a search for a narrow resonance in electron-positron events in the invariant mass range of 150-950 GeV/c{sup 2} using 1.3 fb{sup -1} of p{bar p} collision data at {radical}s=1.96 TeV collected by the CDF II detector at Fermilab. No significant evidence of such a resonance is observed and we interpret the results to exclude the standard model-like Z{prime} with a mass below 923 GeV/c{sup 2} and the Randall-Sundrum graviton with a mass below 807 GeV/c{sup 2} for k/{bar M}{sub pl} = 0.1, both at the 95% confidence level. Combining with di-photon data excludes the Randall-Sundrum graviton for masses below 889 GeV/c{sup 2} for k/{bar M}{sub pl} = 0.1
TL;DR: In this article, the authors search for direct pair production of supersymmetric top quarks and bottom quarks in proton-antiproton collisions at 1.96 TeV, using 295 pb{sup -1} of data recorded by the Collider Detector at Fermilab (CDF II) experiment.
Abstract: We search for direct pair production of supersymmetric top quarks and supersymmetric bottom quarks in proton-antiproton collisions at {radical}(s)=1.96 TeV, using 295 pb{sup -1} of data recorded by the Collider Detector at Fermilab (CDF II) experiment. The supersymmetric top (supersymmetric bottom) quarks are selected by reconstructing their decay into a charm (bottom) quark and a neutralino, which is assumed to be the lightest supersymmetric particle. The signature of such processes is two energetic heavy-flavor jets and missing transverse energy. The number of events that pass our selection for each search process is consistent with the expected standard model background. By comparing our results to the theoretical production cross sections of the supersymmetric top and supersymmetric bottom quarks in the minimal supersymmetric standard model, we exclude, at a 95% confidence level in the frame of that model, a supersymmetric top quark mass up to 132 GeV/c{sup 2} for a neutralino mass of 48 GeV/c{sup 2}, and a supersymmetric bottom quark mass up to 193 GeV/c{sup 2} for a neutralino mass of 40 GeV/c{sup 2}.
TL;DR: In this article, the results of a search for new particles that lead to a Z boson plus jets in p{bar p} collisions at {radical}s = 1.96 TeV using the Collider Detector at Fermilab (CDF II).
Abstract: We present the results of a search for new particles that lead to a Z boson plus jets in p{bar p} collisions at {radical}s = 1.96 TeV using the Collider Detector at Fermilab (CDF II). A data sample with a luminosity of 1.06 fb{sup -1} collected using Z boson decays to ee and {mu}{mu} is used. We describe a completely data-based method to predict the dominant background from standard-model Z+jet events. This method can be similarly applied to other analyses requiring background predictions in multi-jet environments, as shown when validating the method by predicting the background from W+jets in t{bar t} production. No significant excess above the background prediction is observed, and a limit is set using a fourth generation quark model to quantify the acceptance. Assuming BR(b{prime} {yields} bZ) = 100% and using a leading-order calculation of the b{prime} cross section, b{prime} quark masses below 268 GeV/c2 are excluded at 95% confidence level.
TL;DR: The first observation of the associated production of a W boson and a Z boson is reported, based on 1.1 fb;-1 of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron.
Abstract: We report the first observation of the associated production of a W boson and a Z boson. This result is based on 1.1 fb;-1 of integrated luminosity from pp collisions at sqrt[s]=1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We observe 16 WZ candidates passing our event selection with an expected background of 2.7+/-0.4 events. A fit to the missing transverse energy distribution indicates an excess of events compared to the background expectation corresponding to a significance equivalent to 6 standard deviations. The measured cross section is sigma(pp-->WZ)=5.0(-1.6)(+1.8) pb, consistent with the standard model expectation.
TL;DR: In this article, the top quark mass of 174.5 (lumi) pb is derived from a likelihood fit incorporating reconstructed mass distributions representative of signal and background, which is consistent with the standard model prediction.
Abstract: We report the measurements of the t{bar t} production cross section and of the top quark mass using 1.02 fb{sup -1} of p{bar p} data collected with the CDF II detector at the Fermilab Tevatron. We select events with six or more jets on which a number of kinematical requirements are imposed by means of a neural network algorithm. At least one of these jets must be identified as initiated by a b-quark candidate by the reconstruction of a secondary vertex. The cross section is measured to be {sigma}{sub t{bar t}} = 8.3 {+-} 1.0(stat. ){sup +2.0}{sub -1.5}(syst.) {+-} 0.5(lumi.) pb, which is consistent with the standard model prediction. The top quark mass of 174.0 {+-} 2.2(stat.){+-}4.8(syst.) GeV/c{sup 2} is derived from a likelihood fit incorporating reconstructed mass distributions representative of signal and background.
TL;DR: In this article, a measurement of the fraction of longitudinally polarized and right-handed W bosons in top quark decays using data collected with the CDF II detector is presented.
Abstract: The authors present a measurement of the fractions F{sub 0} and F{sub +} of longitudinally polarized and right-handed W bosons in top quark decays using data collected with the CDF II detector. The data set used in the analysis corresponds to an integrated luminosity of approximately 318 pb{sup -1}. They select t{bar t} candidate events with one lepton, at least four jets, and missing transverse energy. The helicity measurement uses the decay angle {theta}*, which is defined as the angle between the momentum of the charged lepton in the W boson rest frame and the W momentum in the top quark rest frame. The cos {theta}* distribution in the data is determined by full kinematic reconstruction of the t{bar t} candidates. They find F{sub 0} = 0.85{sub -0.22}{sup +0.15}(stat){+-}0.06(syst) and F{sub +} = 0.05{sub -0.05}{sup +0.11}(stat) {+-} 0.03(syst), which is consistent with the standard model prediction. They set an upper limit on the fraction of right-handed W bosons of F{sub +} < 0.26 at the 95% confidence level.
01 Jan 2007
TL;DR: The single most precise measurement of the top-quark mass is presented, 170.8+/-2.2(stat.)+/-1.4(syst.) GeV/c(2).
Abstract: We present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. We analyze events from the single lepton plus jets final state (tt-->W(+)bW(-)b-->lnubqq'b). The top-quark mass is extracted using a direct calculation of the probability density that each event corresponds to the tt final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained in situ by the hadronic W boson mass. Using 167 events observed in 955 pb(-1) of integrated luminosity, we achieve the single most precise measurement of the top-quark mass, 170.8+/-2.2(stat.)+/-1.4(syst.) GeV/c(2).
TL;DR: In this article, the authors describe a search for anomalous production of events with two leptons (e or mu) of the same electric charge in p(p) over bar collisions at a center-of-mass energy of 1.96 TeV.
Abstract: We describe a search for anomalous production of events with two leptons (e or mu) of the same electric charge in p(p) over bar collisions at a center-of-mass energy of 1.96 TeV. Many extensions to the standard model predict the production of two leptons of the same electric charge. This search has a significant increase in sensitivity compared to earlier searches. Using a data sample corresponding to 1 fb(-1) of integrated luminosity recorded by the CDF II detector, we observe no significant excess in an inclusive selection (expect 33.2 +/- 4.7 events, observe 44) or in a supersymmetry-optimized selection (expect 7.8 +/- 1.1 events, observe 13.).
TL;DR: In this article, the mass of the top quark was measured from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron.
Abstract: The authors present a measurement of the mass of the top quark from proton-antiproton collisions recorded at the CDF experiment in Run II of the Fermilab Tevatron. They analyze events from the single lepton plus jets final state (t{bar t} {yields} W{sup +}bW{sup -}{bar b} {yields} lvbq{bar q}{bar b}). The top quark mass is extracted using a direct calculation of the probability density that each event corresponds to the t{bar t} final state. The probability is a function of both the mass of the top quark and the energy scale of the calorimeter jets, which is constrained in situ by the hadronic W boson mass. Using 167 events observed in 955 pb{sup -1} of integrated luminosity, they achieve the single most precise measurement of the top quark mass, 170.8 {+-} 2.2(stat.) {+-} 1.4(syst.) GeV/c{sup 2}.
TL;DR: In this article, the first search for heavy, long-lived particles that decay to photons at a hadron collider is presented, using a sample of gamma + jet + missing transverse energy events in pp[over] collisions at square root[s] = 1.96 TeV taken with the CDF II detector.
Abstract: We present the first search for heavy, long-lived particles that decay to photons at a hadron collider. We use a sample of gamma + jet + missing transverse energy events in pp[over] collisions at square root[s] = 1.96 TeV taken with the CDF II detector. Candidate events are selected based on the arrival time of the photon at the detector. Using an integrated luminosity of 570 pb(-1) of collision data, we observe 2 events, consistent with the background estimate of 1.3+/-0.7 events. While our search strategy does not rely on model-specific dynamics, we set cross section limits in a supersymmetric model with [Formula: see text] and place the world-best 95% C.L. lower limit on the [Formula: see text] mass of 101 GeV/c(2) at [Formula: see text].
TL;DR: The results of a search for W-' boson decaying to electron-neutrino pairs in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV were presented in this paper.
Abstract: We present the results of a search for W-' boson decaying to electron-neutrino pairs in p (p) over bar collisions at a center-of-mass energy of 1.96 TeV, using a data sample corresponding to 205 pb(-1) of integrated luminosity collected by the CDF II detector at Fermilab. We observe no evidence for this decay mode and set limits on the production cross section times branching fraction, assuming the neutrinos from W-' boson decays to be light. If we assume the manifest left-right symmetric model, we exclude a W-' boson with mass less than 788 GeV/c(2) at the 95% confidence level.
TL;DR: In this article, the authors reported a measurement of the lifetime of the CDF II detector at the Fermilab Tevatron using fully reconstructed decays, which is $32 higher than the current world average.
Abstract: We report a measurement of the ${\ensuremath{\Lambda}}_{b}^{0}$ lifetime in the exclusive decay ${\ensuremath{\Lambda}}_{b}^{0}\ensuremath{\rightarrow}J/\ensuremath{\psi}{\ensuremath{\Lambda}}^{0}$ in $p\overline{p}$ collisions at $\sqrt{s}=196\text{ }\text{ }\mathrm{TeV}$ using an integrated luminosity of $10\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of data collected by the CDF II detector at the Fermilab Tevatron Using fully reconstructed decays, we measure $\ensuremath{\tau}({\ensuremath{\Lambda}}_{b}^{0})={1593}_{\ensuremath{-}0078}^{+0083}(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0033(\mathrm{syst})\text{ }\text{ }\mathrm{ps}$ This is the single most precise measurement of $\ensuremath{\tau}({\ensuremath{\Lambda}}_{b}^{0})$ and is $32\ensuremath{\sigma}$ higher than the current world average