In the Collider Detector at Fermilab, CDF, we have measured central exclusive production, p+pbar --> p+X+pbar, where X is a pair of leptons or photons and nothing else. In this talk I focus on central masses M(X) > 8 GeV/c2. We measured QED production photon+photon --> e+e-,mu+mu- up to M(l+l-) = 75 GeV/c2, and candidates for photoproduction of Upsilons, photon+pomeron --> Y(1S),Y(2S),Y(3S). I report a search for exclusive photoproduction of Z-bosons, and the status of searches for exclusive two-photons: p+pbar --> p+gamma+gamma+pbar. These measurements constrain the cross section sigma(p+p to p+H+p) at the LHC.
Using the Collider Detector at Fermilab, CDF, we have measured exclusive pi+pi- production at sqrt(s) = 900 GeV and 1960 GeV. The pi+pi- pair is central, |y| < 1.0, and there are no other particles detected in |eta| < 5.9. We discuss the mass spectrum, showing f0(980) and f2(1270) resonances, s-dependence, pT-dependence, and angular distributions.
We report recently published results on central exclusive production of di-jets and di-photons, and exclusive QED production of e+e- pairs. In addition, we discuss preliminary results on exclusive photoproduction of charmonium and bottomonium, exclusive QED production of mu+mu- pairs, and single diffractive W/Z production. All the presented results were extracted from data collected by the CDF II detector from proton-antiproton collisions at a c.m.s. energy of 1.96 TeV. The implications of these results for the Large Hadron Collider are briefly examined.
Experimental results from the CDF experiment at the Tevatron in $p\bar{p}$ collisions at $\sqrt{s}$=1.96 TeV are presented on the diffractive structure function at different values of the exchanged momentum transfer squared in the range $0<Q^2<10,000$ GeV$^2$, on the four-momentum transfer $|t|$ distribution in the region $0<|t|<1$ GeV$^2$ for both soft and hard diffractive events up to $Q^2\approx 4,500$ GeV$^2$, and on the first experimental evidence of exclusive production in both dijet and diphoton events. A novel technique to align the Roman Pot detectors is also presented.
We present recent W and charged lepton asymmetry measurements from the CDF and D0 experiments. Theoretical predictions agree with the CDF W asymmetry, measured using a new matrix element technique. These theoretical predictions are less consistent with the latest lepton asymmetry measurements from D0 and CDF, especially for high charged lepton transverse momentum.
We present final results by the CDF II collaboration on diffractive W and Z production, report on the status of ongoing analyses on diffractive dijet production and on rapidity gaps between jets, and briefly summarize results obtained on exclusive production pointing to their relevance to calibrating theoretical models used to predict exclusive Higgs-boson production at the LHC.
In Run II of the CDF experiment, traditional dilepton triggers are enriched by lepton (electrons or muons) plus track, di-tau and tau plus missing transverse energy triggers at Level-3 dedicated to physical processes including tau leptons. We describe these triggers, along with their physics motivations, implementation and cross-sections and report on their initial performance.
We review the latest underlying event and minimum bias results and discuss the associated problematics with the idea of establishing a solid baseline for the LHC experiments. These measurements include study of the underlying event in Drell-Yan and dijet events, and inclusive differential (in $p_T$) cross sections of centrally ($\midη\mid <$1) produced lambdas, cascades and omegas. We also present recent results on diffraction obtained by the CDF collaboration. Single-diffractive W and Z production is discussed. The first experimental observation of exclusive dijets, exclusive $χ_{c0}$ mesons,…
We report an evidence of \textit{s}-channel single top quark production in $p\bar{p}$ collision at $\sqrt{s}= 1.96 \mathrm{TeV}$ using data with integrated luminosity of $9.4 \mathrm{fb}^{-1}$ collected by the Collider Detector at Fermilab (CDF). We select events with one charged lepton, large missing transverse energy and two bottom quark jets. The observed significance of the result is 3.8 standard deviation from background only prediction. We measure the inclusive cross section to be $1.41^{+0.44}_{-0.42}\mathrm{(stat+syst)} \mathrm{pb}$ assuming $m_t = 172.5 \mathrm{GeV}/c^2$.
We report two complementary measurements of the WW+WZ cross section in the final state consisting of an electron or muon, missing transverse energy, and jets, performed using p\bar{p} collision data at sqrt{s} = 1.96 TeV collected by the CDF II detector. The first method uses the dijet invariant mass distribution while the second more sensitive method uses matrix-element calculations. The result from the second method has a signal significance of 5.4 sigma and is the first observation of WW+WZ production using this signature. Combining the results gives sigma_{WW+WZ} = 16.0 +/- 3.3 pb, in agre…
This thesis presents the evidence, at 3.08 sigma, for the associate production of massive vector bosons (W and Z) in a final state with one lepton, MET and HF-tagged jets, measured with the complete CDF II dataset (9.4fb^-1 of data). The signals, both inclusive diboson production and WW vs WZ/ZZ separately, were extracted from the invariant mass distribution, M_inv(jet1,jet2), of single and double HF-tagged jet pairs. For single-tagged events the b quark vs c quark discrimination was obtained by using a bi-dimensional distribution M_inv(jet1,jet2) vs a flavor-serapator NN. The results, consist…
We present a search for chargino-neutralino associated production using like electric charge dilepton events collected by the CDF II detector at the Fermilab Tevatron in proton-antiproton collisions at $\sqrt{s} = 1.96$ TeV. One lepton is identified as the hadronic decay of a tau lepton, while the other is an electron or muon. In data corresponding to 6.0 fb$^{-1}$ of integrated luminosity, we obtain good agreement with standard model predictions, and set limits on the chargino-neutralino production cross section for simplified gravity- and gauge-mediated models. As an example, assuming that t…
We present a search for the standard model Higgs boson produced in association with a Z boson in data collected with the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45/fb. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electron or muon pairs, we set 95% credibility level upper limits on the ZH production cross section times the H -> bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV/c^2 we observe (expect) a limit of 7.1 (3.9) times the standard model value.
We present a measurement of the top-quark pair production cross-section in proton-antiproton collisions at $\sqrt{s}$=1.96 TeV. The data were collected at the Fermilab Tevatron by the CDF II detector and correspond to an integrated luminosity of 8.8 fb$^{-1}$, representing the complete CDF Run II data set. We select events consistent with the production of top-quark pairs by requiring the presence of two reconstructed leptons, an imbalance in the total event transverse momentum, and jets. At least one jet is required to be identified as consistent with the fragmentation of a bottom quark using…
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 ($t\bar t\to W^+bW^-\bar b\to lνb q \bar q'\bar b$). 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 {\it in situ} by the hadronic $W$ boson mass. Using 16…
We report on a search for the standard model Higgs boson produced in association with a vector boson in the full data set of proton-antiproton collisions at $\sqrt{s} = 1.96$ TeV recorded by the CDF II detector at the Tevatron, corresponding to an integrated luminosity of 9.45 fb$^{-1}$. We consider events having no identified charged lepton, a transverse energy imbalance, and two or three jets, of which at least one is consistent with originating from the decay of a $b$ quark. We place 95% credibility level upper limits on the production cross section times standard model branching fraction f…
We present a search for WW and WZ production in final states that contain a charged lepton (electron or muon) and at least two jets, produced in sqrt(s) = 1.96 TeV ppbar collisions at the Fermilab Tevatron, using data corresponding to 1.2 fb-1 of integrated luminosity collected with the CDF II detector. Diboson production in this decay channel has yet to be observed at hadron colliders due to the large single W plus jets background. An artificial neural network has been developed to increase signal sensitivity, as compared with an event selection based on conventional cuts. We set a 95% confid…
We present a search for the standard model Higgs boson produced in association with a W boson in sqrt(s) = 1.96 TeV p-pbar collision data collected with the CDF II detector at the Tevatron corresponding to an integrated luminosity of 9.45 fb-1. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the W boson to an electron or muon and a neutrino, we set 95% credibility level upper limits on the WH production cross section times the H->bb branching ratio as a function of Higgs boson mass. At a Higgs boson mass of 125 GeV/c2 we observe (expect) a limit of 4.9 (2.8) t…
We present a measurement of the mass of the top quark using data corresponding to an integrated luminosity of 1.9fb^-1 of ppbar collisions collected at sqrt{s}=1.96 TeV with the CDF II detector at Fermilab's Tevatron. This is the first measurement of the top quark mass using top-antitop pair candidate events in the lepton + jets and dilepton decay channels simultaneously. We reconstruct two observables in each channel and use a non-parametric kernel density estimation technique to derive two-dimensional probability density functions from simulated signal and background samples. The observables…
This Letter reports a search for a narrow resonant state decaying into two $W$ bosons and a bottom-antibottom quark pair where one $W$ boson decays leptonically and the other decays into a quark-antiquark pair. The search is particularly sensitive to top-antitop resonant production. We use the full data sample of proton-antiproton collisions at a center-of-mass energy of 1.96 TeV collected by the CDF II detector at the Fermilab Tevatron, corresponding to an integrated luminosity of 9.45 fb$^{-1}$. No evidence for resonant production is found and upper limits on the production cross section tim…
We present a measurement of the mass of the top quark from ppbar collisions at 1.96 TeV observed with the Collider Detector at Fermilab (CDF) at the Fermilab Tevatron Run II. The events have the decay signature of ppbar to ttbar in the lepton plus jets channel in which at least one jet is identified as coming from a secondary vertex and therefore a b-hadron. The largest systematic uncertainty, the jet energy scale (JES), is convoluted with the statistical error using an in-situ measurement of the hadronic W boson mass. We calculate a likelihood for each event using leading-order ttbar and W+je…
We present additional studies of the kinematics of the anomalous events observed by the CDF experiment. These events contain a high-$p_T$ lepton, large transverse missing energy ($\MET$), and 2 or 3 high-$E_T$ jets, one of which contains both a displaced secondary vertex and a soft lepton. Previous articles detailed the selection and the kinematic properties of these events. In the present paper, we use several phenomenological approaches to model these data and to estimate their production cross section.
The leptonic asymmetry in semileptonic ttbar decays is measured with the CDF detector using the full Tevatron Run II dataset, which corresponds to 9.4 fb^-1 of integrated luminosity. The measured asymmetry is extrapolated to the full kinematic range and the measured value of A_FB^lep = 0.094^+0.032_-0.029 is compared to the NLO prediction A_FB^lep = 0.038 +/- 0.003.
The chargino-neutralino production with subsequent leptonic decays is one of the most promising supersymmetry (SUSY) signatures at the Tevatron proton-antiproton collider. We present the most recent results on the search for the three-lepton and missing-transverse-energy SUSY signature using 3.2 fb-1 of data collected with the CDF II detector. The results are interpreted within the minimal supergravity (mSUGRA) scenario.
We present results of a search at CDF in 929 pb-1 of ppbar collisions at 1.96 TeV for the anomalous production of events containing a high-transverse momentum charged lepton (either electron or muon) and photon, accompanied by missing transverse energy (MET), and/or additional leptons and photons, and jets (X). We use the same selection criteria as in a previous CDF Run I search, but with an order-magnitude larger data set, a higher ppbar collision energy, and the CDF II detector. We find 163 Lepton + Photon + MET + X events, compared to an expectation of 150.6+-13.0 events. We observe 74 Mult…
We summarize some of the the most recent CDF and DO results from the 1992-1995 collider run at the Fermilab Tevatron. These include a detailed examination of the heavy flavor content of W+jet data made by CDF.We found in this study that the rate and the kinematic properties of the event subsample, featuring soft lepton and secondary vertex in the same jet, are statistically difficult to accommodate with the Standard Model simulation. CDF has also searched for new physics in events with a photon, a lepton and missing transverse energy. Finally, the results of the two collaborations in their sea…
We report new results from CDF on single-diffractive dijet and W/Z production, and on exclusive dijet, diphoton, and dilepton production in proton-antiproton collisions at sqrt{s}=1.96 TeV at the Fermilab Tevatron. The measured exclusive dijet and diphoton cross sections provide a test of theoretical predictions for exclusive Higgs production at the LHC.
We present results of the search for the super-symmetric partner of the top quark, the stop quark, decaying to a b-quark and chargino with the subsequent chargino decay into a neutralino, lepton and neutrino. Using the data sample corresponding to 2.7 inv fb of integrated luminosity, collected with the CDF Detector of the Tevatron collider, we reconstruct the stop mass of candidate events and set 95% C. L. upper limits on masses of the stop quark, chargino and neutralino and the branching ratio of chargino to neutralino+lepton+neutrino.
We present a measurement of the top quark mass in the lepton+jets and dilepton channels of $t\bar{t}$ decays using the template method. The data sample corresponds to an integrated luminosity of 5.6 fb$^{-1}$ of $p\bar{p}$ collisions at Tevatron with $\sqrt{s}=1.96$ TeV, collected with the CDF II detector. The measurement is performed by constructing templates of three kinematic variables in the lepton+jets and two kinematic variables in the dilepton channel. The variables are two reconstructed top quark masses from different jets-to-quarks combinations and the invariant mass of two jets from …
We report on recent measurements of the top quark mass using t t-bar candidate events selected in ~320/pb of data from the "Run II" operation period of the Tevatron p p-bar collider. More emphasis is given on the best single measurement to date Mtop = 173.5 +3.9 -3.8 GeV/c^2, provided by CDF using the "lepton plus jets" channel, where one W decays to a lepton-neutrino pair and the other into quarks (top quarks decay to Wb almost 100% of the time).
At the Fermilab Tevatron, the CDF detector is used to study diboson production in $p\bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV. We report recent diboson production measurements, limits on anomalous triple gauge couplings and latest results from semi-leptonic diboson searches.
We present a measurement of the ratio of the top-quark branching fractions $R=\mathcal{B}(t\rightarrow Wb)/\mathcal{B}(t\rightarrow Wq)$, where $q$ represents quarks of type $b$, $s$, or $d$, in the final state with a lepton and hadronic jets. The measurement uses $\sqrt{s}$ = 1.96 TeV proton--antiproton collision data from 8.7 fb$^{-1}$ of integrated luminosity collected with the Collider Detector at Fermilab during Run II of the Tevatron. We simultaneously measure $R=0.94 \pm 0.09$ (stat+syst), the $t\bar{t}$ production cross section $σ_{t \bar t} = 7.5 \pm 1.0$ (stat+syst) pb. The magnitude…
The results based on 1992-95 data (Run 1) from the CDF and DO experiments on the measurements of the W boson mass and width are presented, along with the combined results. We report a Tevatron collider average M_W = 80.456 +- 0.059 GeV. We also report the Tevatron collider average of the directly measured W boson width Gamma_W = 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…
Decays that are highly suppressed in the standard model are excellent places to search for effects of new physics. Decays mediated by flavor-changing neutral currents are forbidden at tree level in the SM, and are often further suppressed by helicity and the Glashow-Iliopoulos-Maiani mechanism. Exclusive final states with charged lepton pairs are a particular strength of the CDF experiment due to the large bottom and charm production cross section and the ability to efficiently separate signal from background. CDF has searched for and set the world's best limits on the rare flavor-changing neu…
We present results of a search in 929 pb-1 of ppbar collisions at 1.96 TeV for the anomalous production of events containing a charged lepton (electron or muon) and a photon, both with high transverse momentum, accompanied by additional signatures, X, including missing transverse energy and additional leptons and photons. We use the same selection criteria as in the previous CDF Run I search, but with an order-magnitude larger data set, a higher ppbar collision energy, and the CDF II detector.
We present a measurement of the top quark mass with t-tbar dilepton events produced in p-pbar collisions at the Fermilab Tevatron $\sqrt{s}$=1.96 TeV and collected by the CDF II detector. A sample of 328 events with a charged electron or muon and an isolated track, corresponding to an integrated luminosity of 2.9 fb$^{-1}$, are selected as t-tbar candidates. To account for the unconstrained event kinematics, we scan over the phase space of the azimuthal angles ($ϕ_{ν_1},ϕ_{ν_2}$) of neutrinos and reconstruct the top quark mass for each $ϕ_{ν_1},ϕ_{ν_2}$ pair by minimizing a $χ^2$ function in t…
Experimental results on diffraction from the Fermilab Tevatron collider obtained by the CDF experiment are reviewed and compared. We report on the diffractive structure function obtained from dijet production in the range $0<Q^2<10,000$ GeV$^2$, and on the $|t|$ distribution in the region $0<|t<1$ GeV$^2$ for both soft and hard diffractive events up to $Q^2\approx 4,500$ GeV$^2$. Results on single diffractive W/Z production, forward jets, and central exclusive production of both dijets and diphotons are also presented.
A measurement of Delta m_d is performed using inclusive lepton+vertex events at CDF. A probability based Same-Side Tagger was developed to tag the initial b-flavor of the B^0_d, which suppresses tagging on B-decay products. We find Delta m_d = 0.42 +/- 0.09 +/- 0.03 ps^-1.
We present a measurement of the top-quark mass using a sample of $t\bar{t}$ events in 5.7 fb$^{-1}$ of integrated luminosity from $p\bar{p}$ collisions at the Fermilab Tevatron with $\sqrt{s} =$ 1.96 TeV and collected by the CDF II Detector. We select events having no identified charged leptons, large missing transverse energy, and four, five, or six jets with at least one jet tagged as coming from a $b$ quark. This analysis considers events from the semileptonic \ttbar decay channel, including events that contain tau leptons. The measurement is based on a multidimensional template method. We …
Results from studies on exclusive production of electron-position pair, di-photon, and di-jet production at CDF in proton-antiproton collisions at the Fermilab Tevatron are presented. The first observation and cross section measurements of exclusive e+e- and di-jet production in hadron-hadron collisions are emphasized.
We present measurements of the top-antitop production cross section in b-tagged lepton + jets events from proton-antiproton collisions at 1.96 TeV using the CDF detector at Fermilab. B-jets are tagged with either a secondary vertex algorithm, or a soft lepton tagger that identifies muons from B hadron semileptonic decays. With Tevatron Run II data, we estimate the top-antitop signal fraction in two different ways: by estimating the various background contributions, and by fitting directly the leading jet transverse energy spectrum for the signal and background contributions. A subset of the sa…
We present results of searches for new physics in final states with photons at CDF in approximately 1 fb-1 of ppbar collisions at 1.96 TeV. We give an overview of the data-driven photon background estimation techniques used for the analyses. We report on a search for diphoton peaks and signature-based searches for diphoton+X, lepton+photon+X (X = electron, muon, missing transverse energy, photon) and ttbar+photon.
This article presents a measurement of the top quark mass using the CDF II detector at Fermilab. Colliding beams of protons and anti-protons at Fermilab's Tevatron (sqrt{s}=1.96 TeV) produce top/anti-top pairs, which decay to W^+W^-bbbar; events are selected where one W decays to hadrons, and one W decays to either e or mu plus a neutrino. The data sample corresponds to an integrated luminosity of approximately 318 pb^-1. A total of 165 ttbar events are separated into four subsamples based on jet transverse energy thresholds and the number of b jets identified by reconstructing a displaced ver…
Observing WZ/ZZ production at the Tevatron in a final state with a lepton, missing transverse energy and jets is extremely difficult because of the low signal rate and the huge background. In an attempt to increase the acceptance we study the sample where three high-energy jets are reconstructed, where about 1/3 of the diboson signal events are expected to end. Rather than choosing the two E$_{T}$-leading jets to detect a Z signal, we make use of the information carried by all jets. To qualify the potential of our method, we estimate the probability of observing an inclusive diboson signal at …
We present the results of a search for associated production of the lightest chargino and next-to-lightest neutralino using 1 fb$^{-1}$ of $\sqrt s$ = 1.96 TeV p$\rm \bar p$ data collected with the CDF detector at the Tevatron. We combine the results of several multi-lepton final states to set upper limits on the cross section times branching ratio for chargino-neutralino production as a function of the chargino mass.
The study of processes containing tau leptons in the final state will play an important role at Tevatron Run II. Such final states will be relevant both for electroweak studies and measurements as well as in searches for physics beyond the Standard Model. The present paper discuss the physics opportunities and challenges related to the implementation of new set of triggers able to select events containing tau candidates in the final state. We illustrate, in particular, the physics capabilities for a variety of new physics scenarios such as supersymmetry (SUSY), SUSY with R-parity violation, wi…
The Collider Detector at Fermilab, CDF, observed for the first time in hadron-hadron collisions photon-photon to e+e- and mu+mu-, photon-pomeron to J/psi and psi(2S), and pomeron-pomeron to photon+photon and to chi_c. Exclusive pi+pi- production by double pomeron exchange was also measured at p+pbar CM energies 900 GeV and 1960 GeV, showing f0 and f2 resonance structures.
We present combined results on the search for neutral supersymmetric Higgs bosons with data collected at the CDF and D0 experiments. Data were collected in proton-antiproton collisions at sqrt(s) = 1.96 TeV during Run II of the Tevatron. The searches considered cover the main production and decay mechanisms for Higgs bosons in tau lepton and bottom quark final states. The resulting combination is interpreted in the context of different scenarios within the Minimal Supersymmetric Standard Model.
In CDF we have observed several exclusive processes: 2-photon --> e+e- and --> mu+mu-, photon+pomeron --> J/psi and psi(2S), and pomeron+pomeron --> chi_c. The cross sections agree with QED, HERA photoproduction data, and theoretical estimates of gg --> chi_c with another gluon exchanged to screen the color. This observation of exclusive chi_c, together with earlier observations of exclusive dijets and exclusive 2-photon candidates, support some theoretical predictions for p+p --> p+H+p at the LHC. Exclusive dileptons offer the best means of precisely calibrating forward proton spectrometers.
With growing datasets collected by the CDF II experiment, studies of the spectroscopy of mesons containing heavy quarks become more exciting. The CDF experiment has good capabilities in both charm and bottom sector. This capability allowed also to contribute to the study of the zoo of states called X,Y,Z. In this area we present a recent update of the mass measurement of X(3872). The result m(X(3872)) = 3871.61 +- 0.16 +- 0.19 MeV is currently the most precise measurement in the world. In addition, we report evidence for a new narrow resonance, Y(4140), the first to be seen in the J/psi phi de…
We describe a measurement of the top quark mass using events with two charged leptons collected by the CDF II detector from $p\bar{p}$ collisions with $\sqrt s = 1.96$ TeV at the Fermilab Tevatron. The likelihood in top mass is calculated for each event by convoluting the leading order matrix element describing $q\bar{q} \to t\bar{t} \to b\ellν_{\ell}\bar{b}\ell'ν_{\ell'}$ with detector resolution functions. The presence of background events in the data sample is modeled using similar calculations involving the matrix elements for major background processes. In a data sample with integrated lu…
We describe a measurement of the charge asymmetry of leptons from W boson decays in the rapidity range 0<|y_l|<2.5 using W --> enu, munu events from 110+/-7 pb^{-1}of data collected by the CDF detector during 1992-95. The asymmetry data constrain the ratio of d and u quark momentum distributions in the proton over the x range of 0.006 to 0.34 at Q2 \approx M_W^2. The asymmetry predictions that use parton distribution functions obtained from previously published CDF data in the central rapidity region (0.0<|y_l|<1.1) do not agree with the new data in the large rapidity region (|y_l|>1.1).
We report the recent evidence for a new narrow structure, Y(4140), decaying to the $J/ψϕ$ final state, in exclusive $B^+\to J/ψϕK^+$ decays in a data sample corresponding to an integrated luminosity of 2.7 \ifb collected at the CDF II detector. This narrow structure with its mass well above open charm pairs is unlikely to be a candidate for a conventional charmonium state. From a study of the X(3872) mass and width based on the world's largest sample of $X(3872)\to J/ψπ^+π^-$ decays, we find that our X(3872) signal is consistent with a single state, and leads to the most precise measurement of…
We present a search for new physics in events with two high $p_T$ leptons of the same electric charge, using data with an integrated luminosity of 6.1 fb$^{-1}$. The observed data are consistent with standard model predictions. We set 95% C.L. lower limits on the mass of doubly-charged scalars decaying to like-sign dileptons, $m_{H^{\pm\pm}}> 190-245$ GeV/$c^2$, depending on the decay mode and coupling.
Measurements of the $B_u$, $B_d$, and $B_s$ meson lifetime using semileptonic $B_u \rightarrow e νD^0 X, B_d \rightarrow e νD^* X, B_s \rightarrow l νD_s X$ events and exclusive $B_u \rightarrow ψ^{(\prime)} K^{(*)}, B_d \rightarrow ψ^{(\prime)} K^{(*)}_{(s)}, B_s \rightarrow ψϕ$ events are presented. These results used the precise position measurements of the CDF SVX silicon vertex detector and were obtained from a 19.3 pb$^{-1}$ sample of 1.8 TeV $\overline{p}p$ collisions collected in 1992-93 at the Fermilab Tevatron collider. Comparisons with previous measurements will be shown.
Recently, the CDF collaboration reports an anomaly in dijet mass distribution in association with a lepton and missing energy. We discuss a possibility that the origin of the lepton and missing energy comes not from a W boson but a new boson particle, which is also responsible for the dijet mass peak. We show that such a situation can be realized in the framework of the minimal supersymmetric standard model and the dijet anomaly can be explained.
We report on a study of the dijet invariant-mass distribution in events with one identified lepton, a significant imbalance in the total event transverse momentum, and two jets. This distribution is sensitive to the possible production of a new particle in association with a $W$ boson, where the boson decays leptonically. We use the full data set of proton-antiproton collisions at 1.96 TeV center-of-mass energy collected by the Collider Detector at the Fermilab Tevatron and corresponding to an integrated luminosity of 8.9 fb$^{-1}$. The data are found to be consistent with standard-model expec…
Evidence for a positive longitudinal double-spin asymmetry <A_1^rho> = 0.24 +-0.11 (stat) +-0.02 (syst) in the cross section for exclusive diffractive rho^0(770) vector meson production in polarised lepton-proton scattering was observed by the HERMES experiment. The longitudinally polarised 27.56 GeV HERA positron beam was scattered off a longitudinally polarised pure hydrogen gas target. The average invariant mass of the photon-proton system has a value of <W> = 4.9 GeV, while the average negative squared four-momentum of the virtual photon is <Q^2> = 1.7 GeV^2. The ratio of the present resul…
We review the measurements of the top quark mass by the CDF and D-Zero collaborations using Run I data in excess of 100 inverse picobarns. The D-Zero collaboration has recently updated its measurement of the top quark mass in the lepton + jets channel. The world average of the top quark mass from the CDF and D-Zero measurements in the lepton + jets channel now stands at 175.6 +/- 5.5 GeV/c**2.
We present the most recent measurements of top quark pairs production and top quark properties in proton-antiproton collisions with center-of-mass energy of 1.96 TeV using CDF II detector at the Tevatron. The combination of top pair production cross section measurements and the direct measurement of top quark width are reported. The test of Standard Model predictions for top quark decaying into $b$-quarks, performed by measuring the ratio $R$ between the top quark branching fraction to $b$-quark and the branching fraction to any type of down quark is shown. The extraction of the CKM matrix ele…
