Searching for and potential discovery of Higgs boson(s) both within and beyond the standard model is perhaps the most visible physics goal of the current Fermilab Tevatron program. In this proceeding, recent results from both the CDF and DØexperiments based on analyses of datasets with integrated luminosities between 1.7 and 3.0 fb$^{-1}$ are summarized. The combined Tevatron cross section upper limits on the production of a standard model Higgs boson are fast approaching the expected standard model values for a wide mass range. Particularly, the Tevatron has now excluded a standard model Higgs boson with a mass of 170 GeV at 95% C.L.
We present the results of a search for the spin-singlet P-wave state hc(1 1P1) of charmonium formed through proton-antiproton annihilation at Fermilab experiment E835. The decay channels whjich were studied were ppbar -> J/psi + X -> e^+e^- + X, ppbar -> J/psi + pi0 -> e^+e^- + 2gamma, ppbar -> J/psi + pi0pi0 -> e^+e^- + 4gamma, and the neutral channel ppbar -> eta_c gamma -> (2gamma) gamma. The decay ppbar -> J/psi gamma -> e^+e^- gamma, into which 1P1 decay is forbidden by C-parity conservation, was also examined for comparison The 90% confidence upper limits for the decay channels studied i…
The ttbar spin correlation at production is a fundamental prediction of QCD and a potentially incisive test of new physics coupled to top quarks. We measure the ttbar spin state in ppbar collisions at sqrt(s) = 1.96 TeV using 1001 candidate events in the lepton plus jets decay channel reconstructed in the CDF II detector. In the helicity basis, for a top-quark mass of 172.5 GeV/c^2, we find a spin correlation coefficient kappa = 0.60 +/- 0.50 (stat) +/- 0.16 (syst), consistent with the QCD prediction, kappa ~= 0.40.
We present a measurement of the inclusive jet cross section in ppbar interactions at sqrt{s}=1.96 TeV using 385 pb^{-1} of data collected with the CDF II detector at the Fermilab Tevatron. The results are obtained using an improved cone-based jet algorithm (Midpoint). The data cover the jet transverse momentum range from 61 to 620 GeV/c, extending the reach by almost 150 GeV/c compared with previous measurements at the Tevatron. The results are in good agreement with next-to-leading order perturbative QCD predictions using the CTEQ6.1M parton distribution functions.
We report on results obtained at the Tevatron by the CDF and D0 collaborations up to June 2008 (2.4 fb-1), on searches for standard model (SM) Higgs bosons having a high mass (135-200 GeV). High mass Higgs bosons decay dominantly in WW and the presented searches are performed in the leptonic decay modes of the W's. Both direct production (ppbar -> H) and associated production (ppbar -> WH) are studied and eventually combined with all channels available at the Tevatron. Prospects for SM Higgs searches with the full projected Tevatron statistics are also given.
A search for direct production of scalar bottom quarks (sb) is performed with 310 pb-1 of data collected by the DO experiment in ppbar collisions at sqrt(s)=1.96 TeV at the Fermilab Tevatron Collider. The topology analyzed consists of two b jets and an imbalance in transverse momentum due to undetected neutralinos chi0_1, with chi0_1 assumed to be the lightest supersymmetric particle. We find the data consistent with standard model expectations, and set a 95% C.L. exclusion domain in the (m_sb,m_chi0_1) mass plane, improving significantly upon the results from Run I of the Tevatron.
This Letter describes a direct measurement of the $W$ boson total decay width, $\gw$, using the Collider Detector at Fermilab. The measurement uses an integrated luminosity of $90\invpb$, collected during the 1994--1995 run of the Fermilab Tevatron $p\pbar$ collider. The width is determined by normalizing predicted signal and background distributions to 49844 $\wenu$ candidates and 21806 $\wmunu$ candidates in the transverse-mass region $M_T<200\gev$ and then fitting the predicted shape to the 438 electron events and 196 muon events in the high-$M_T$ region, $100<M_T<200\gev$. The result is $Γ…
We present the first observation of the Zgamma to nunugamma process at the Tevatron at 5.1 standard deviations significance, based on 3.6 fb-1 of integrated luminosity collected with the D0 detector at the Fermilab Tevatron ppbar Collider at sqrt{s} = 1.96 TeV. The measured Zgamma cross section multiplied by the branching fraction of Z to nunu is 32 +- 9 (stat.+syst.) +- 2 (lumi.) fb for the photon ET > 90 GeV. It is in agreement with the standard model prediction of 39 +- 4 fb. We set the most restrictive limits on anomalous trilinear Zgammagamma and ZZgamma gauge boson couplings at a hadron …
The CDF and DØcollaborations continue to search for new physics using more than 100~pb$^{-1}$ of \xxbar{p} collisions at $\sqrt{s}=1.8$ TeV collected at the Fermilab Tevatron. We present recent results from both experiments on R-parity violating Supersymmetry and $Z'$/Technicolor production with $ee$ and \xxbar{t} final states. In addition we introduce Sherlock, a new quasi-model-independent search strategy.
We present the first observation in hadronic collisions of the electroweak production of vector boson pairs (VV, V=W,Z) where one boson decays to a dijet final state . The data correspond to 3.5 inverse femtobarns of integrated luminosity of ppbar collisions at sqrt(s)=1.96 TeV collected by the CDFII detector at the Fermilab Tevatron. We observe 1516+/-239(stat)+/-144(syst) diboson candidate events and measure a cross section sigma(ppbar->VV+X) of 18.0+/-2.8(stat)+/-2.4(syst)+/-1.1(lumi) pb, in agreement with the expectations of the standard model.
We measure the ratio of cross sections, σ(ppbar -> Z + b jet)/σ(ppbar -> Z + jet), for associated production of a Z boson with at least one jet. The ratio is also measured as a function of the jet transverse momentum, jet pseudorapidity, Z boson transverse momentum, and the azimuthal angle between the Z boson and the closest jet for events with at least one b jet. These measurements use data collected by the D0 experiment in Run II of Fermilab's Tevatron ppbar Collider at a center-of-mass energy of 1.96 TeV, and correspond to an integrated luminosity of 9.7 fb$^{-1}$. The results are compared …
This paper reviews recent measurements by the D0 and CDF collaborations in pbarp collisions at the Fermilab Tevatron at sqrt{s} = 1.96 TeV of W and Z boson production cross sections and asymmetries. Results from both experiments for the search of the Higgs boson predicted by the standard model in four different decay channels are also presented.
We present measurements of the tWb coupling form factors using information from electroweak single top quark production and from the helicity of W bosons from top quark decays in ttbar events. We set upper limits on anomalous tWb coupling form factors using data collected with the D0 detector at the Tevatron ppbar collider corresponding to an integrated luminosity of 5.4 fb^-1.
This talk at the XVIII International Conference on Physics in Collision, Frascati, Italy, June 17-19, 1998, presents CDF and D0 results on W and Z Boson Production Cross Sections, the W Boson Width, Rare W Boson Decays, Trilinear Gauge Boson Couplings, and the W Boson Mass.
The \d0 (DZERO) Detector at Fermilab is currently collecting data since March 1, 2001, called Run 2. The detector has undergone an extensive upgrade to participate in the Run 2 data taking. The design of the detector meets the requirements of the high luminosity environment provided by the accelerator. This paper describes the upgraded detector subsystems and gives an outline of the physics potentials associated with the upgrade.
We present results from a measurement of double diffraction dissociation in $\bar pp$ collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width $Δη^0>3$ (overlapping $η=0$) is found to be $4.43\pm 0.02{(stat)}{\pm 1.18}{(syst) mb}$ [$3.42\pm 0.01{(stat)}{\pm 1.09}{(syst) mb}$] at $\sqrt{s}=1800$ [630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.
This writeup is an introduction to some of the experimental issues involved in performing electroweak and B physics measurements at the Fermilab Tevatron. In the electroweak sector, we discuss W and Z boson cross section measurements as well as the measurement of the mass of the W boson. For B physics, we discuss measurements of B^0/\bar{B^0} mixing and CP violation. This paper is geared towards nonexperts who are interested in understanding some of the issues and motivations for these measurements and how the measurements are carried out.
We present the first measurements of the ratios of cross sections, σ(ppbar -> Z+c jet)/σ(ppbar -> Z+jet) and σ(ppbar -> Z+c jet)/σ(ppbar -> Z+b jet) for the associated production of a Z boson with at least one charm or bottom quark jet. Jets have transverse momentum p_{T}>20 GeV and pseudorapidity |η|<2.5. These cross section ratios are measured differentially as a function of jet and $Z$ boson transverse momenta, based on 9.7 fb^{-1} of ppbar collisions collected with the D0 detector at the Fermilab Tevatron Collider at sqrt(s) = 1.96 TeV. The measurements show significant deviations from per…
This paper presents a review of the study of Exclusive Central Production at a Center of Mass energy of $\sqrt{s}=40$ GeV at the Fermilab Fixed Target program. In all reactions reviewed in this paper, protons with an energy of 800 GeV were extracted from the Tevatron accelerator at Fermilab and directed to a Liquid Hydrogen target. The states reviewed include $π^+π^-$, $K^0_s K^0_s$, $ K^0_sK^\pmπ^\mp$, $ϕϕ$ and $D^{*\pm}$. Partial Wave Analysis results will be presented on the light states but only the cross section will be reviewed in the diffractive production of $D^{*\pm}$
The standard model is a successful but limited theory. There is significant theoretical motivation to believe that new physics may appear at the energy scale of a few TeV, the lower end of which is currently probed by the Fermilab Tevatron Collider. The methods used to search for physics beyond the standard model in a model independent way and the results of these searches based on 1.0 fb-1 of data collected with the D0 detector and 2.0 fb^-1 at the CDF detector are presented.
We address known discrepancies between the heavy flavor properties of jets produced at the Tevatron collider and the prediction of conventional-QCD simulations. In this study, we entertain the possibility that these effects are real and due to new physics. We show that all anomalies can be simultaneously fitted by postulating the additional pair production of light bottom squarks with a 100% semileptonic branching fraction.
We present an idea for a future D0-D0bar mixing and CP violation experiment to run at the Fermilab Tevatron. We estimate that in three years of running, such an experiment could reconstruct an order of magnitude more flavor-tagged D0->K+pi- decays than will be reconstructed by the B-factory experiments with their full data sets. The resulting sensitivity to CP-violating parameters |q/p| and Arg(q/p) is calculated from a global fit to CP-violating observables, and it is found to be much greater than current world sensitivity.
We present a search for exclusive Z boson production in proton-antiproton collisions at sqrt(s) = 1.96 TeV, using the CDF II detector at Fermilab. We observe no exclusive Z->ll candidates and place the first upper limit on the exclusive Z cross section in hadron collisions, sigma(exclu) < 0.96 pb at 95% confidence level. In addition, we observe eight candidate exclusive dilepton events from the quantum electrodynamic process ppbar->gammagamma->p+ll+pbar, and measure the cross section for M(ll) > 40 GeV/c2 and |eta(l)| < 4 to be sigma = 0.24^{+0.13}_{-0.10} pb, which is the first measurement fo…
We present a search for the production of neutral Higgs bosons phi decaying into tau+tau- final states in ppbar collisions at a center-of-mass energy of 1.96 TeV. The data, corresponding to an integrated luminosity of approximately 1 fb-1, were collected by the D0 experiment at the Fermilab Tevatron Collider. Limits on the production cross section times branching ratio are set. The results are interpreted in the minimal supersymmetric standard model yielding limits that are the most stringent to date at hadron colliders.
The mass of the top quark has been measured at Fermilab using the Tevatron ppbar collider to a precision of less than 1%. I discuss the individual measurements that go into this result and its impact on our understanding of the standard model of the electroweak interactions.
We report results of a search for particles with anomalously high ionization in events with a high transverse energy jet and large missing transverse energy in $2.4$ fb$^{-1}$ of integrated luminosity collected by the D0 experiment at the Fermilab Tevatron $p\bar{p}$ collider. Production of such particles (quirks) is expected in scenarios with extra QCD-like {\it SU(N)} sectors, and this study is the first dedicated search for such signatures. We find no evidence of a signal and set a lower mass limit of 107 ~GeV for the mass of a charged quirk with strong dynamics scale $Λ$ in the range from …
Selected quantum chromodynamics measurements performed at the Fermilab Run II Tevatron ppbar collider running at sqrt{s}=1.96 TeV by D0 and CDF Collaborations are presented. Events with W/Z+jets productions are used to measure many kinematic distributions allowing extensive tests and tunes of predictions from perturbative QCD at next-to-leading order and Monte-Carlo event generators.
The top quark, discovered at the Tevatron in 1995, is a very interesting particle. Precise measurement of the top properties using large data samples will allow stringent tests of the Standard Model and offer a unique window on new physics. In this report will be reviewed the status of the current knowledge of the top quark as provided by the Run I results of the CDF and D0 experiment. A first look at various preliminary measurements obtained with data collected during Run II will be also presented.
We present combined searches for the Low Mass Standard Model Higgs boson at a center-of-mass energy of $\sqrt{s}=$1.96 TeV, using up to 5 fb$^{-1}$ of data collected with the D0 detector at the Fermilab Tevatron collider. The major contributing processes are associated production ($WH\to lνbb$, $ZH\toννbb$, $ZH\to ll bb$). The significant improvements across the full mass range resulting from the larger data sets and improved analyses as well as future prospects are discussed.
A search for leptoquarks has been performed in 310 pb-1 of data from ppbar collisions at a center-of-mass energy of 1.96 TeV, collected by the D0 detector at the Fermilab Tevatron Collider. The topology analyzed consists of acoplanar jets with missing transverse energy. The data show good agreement with standard model expectations, and a lower mass limit of 136 GeV has been set at the 95% C.L. for a scalar leptoquark decaying exclusively into a quark and a neutrino.
We report the results of a search for a charged Higgs boson in the decays of top quarks produced in \ppbar collisions at a center-of-mass energy of 1.96 TeV. We use a data sample corresponding to an integrated luminosity of 193/pb collected by the upgraded Collider Detector at Fermilab. No evidence for charged Higgs production is found, allowing 95% C.L. upper limits to be placed on BR(t->H^+b) for different charged Higgs decay scenarios. In addition, we present in the MSSM (mH,tan beta) plane the first exclusion regions with radiative and Yukawa coupling corrections.
Using 7.3 pb-1 of ppbar collisions collected by the D0 detector at the Fermilab Tevatron, we measure the distribution of the variable \phistar, which probes the same physical effects as the Z/gamma* boson transverse momentum, but is less susceptible to the effects of experimental resolution and efficiency. A QCD prediction is found to describe the general features of the \phistar distribution, but is unable to describe its detailed shape or dependence on boson rapidity. A prediction that includes a broadening of transverse momentum for small values of the parton momentum fraction is strongly d…
We report on a study of color coherence effects in ppbar collisions at a center of mass energy sqrt(s)=1.8 TeV. The data were collected with the D0 detector during the 1992-1993 run of the Fermilab Tevatron Collider. We observe the presence of initial-to-final state color interference with the spatial correlations between soft and hard jets in multijet events in the central and in forward pseudorapidity regions. The results are compared to Monte Carlo simulations with different color coherence implementations and to the predictions of O(alpha_s^3) QCD calculations.
We present the results of searches for Standard Model Higgs, charged stable massive particles, dijet mass resonances, and heavy neutral gauge bosons in Tevatron ppbar collisions at sqrt s = 1.8 TeV using the CDF and D0 detectors.
We present the first direct experimental bound on the total decay width of the top quark using 955pb^-1 of the Tevatron's ppbar collisions recorded by the Collider Detector at Fermilab. We identify 253 top-antitop pair candidate events. The distribution of reconstructed top quark mass from these events is fitted to templates representing different values of the top quark width. Using a confidence interval based on likelihood ratio ordering, we extract an upper limit at 95% C.L. of Gamma_t <13.1 GeV for an assumed top quark mass of 175 GeV/c^2.
The recent results on various Beyond the Standard Model (BSM) Higgs boson searches performed by the DZERO experiment at the Tevatron are presented here. In particular, the Higgs bosons in supersymmetric models and fermiophobic scenario have been investigated. No significant excess over the Standard Model (SM) expectations have been observed and accordingly limits have been established on the corresponding model parameters.
We report on a search for Standard Model t-channel and s-channel single top quark production in ppbar collisions at a center of mass energy of 1.96 TeV. We use a data sample corresponding to 162 pb^{-1} recorded by the upgraded Collider Detector at Fermilab. We find no significant evidence for electroweak top quark production and set upper limits at the 95% confidence level on the production cross section, consistent with the Standard Model: 10.1 pb for the t-channel, 13.6 pb for the s-channel and 17.8 pb for the combined cross section of t- and s-channel.
We describe a search for evidence of minimal supergravity (mSUGRA) in 92.7 pb^(-1) of data collected with the DØdetector at the Fermilab Tevatron ppbar collider at center of mass energy of 1.8 TeV. Events with a single electron, four or more jets, and large missing transverse energy were used in this search. The major backgrounds are from W+jets, misidentified multijet, ttbar, and WW production. We observe no excess above the expected number of background events in our data. A new limit in terms of mSUGRA model parameters is obtained.
We present a search for hypothetical vector-like quarks in ppbar collisions at sqrt(s) = 1.96 TeV. The data were collected by the D0 detector at the Fermilab Tevatron Collider and correspond to an integrated luminosity of 5.4 fb^(-1). We select events with a final state composed of a W or Z boson and a jet consistent with a heavy object decay. We observe no significant excess in comparison to the background prediction and set limits on production cross sections for vector-like quarks decaying to W+jet and Z+jet. These are the most stringent mass limits for electroweak single vector-like quark …
We present a search for anomalous triple gauge couplings (ATGC) in WW and WZ boson production. The boson pairs are produced in ppbar collisions at sqrt{s}=1.96 TeV, and the data sample corresponds to 350 pb-1 of integrated luminosity collected with the CDF II detector at the Fermilab Tevatron. In this search one W decays to leptons, and the other boson (W or Z) decays hadronically. Combining with a previously published CDF measurement of Wgamma boson production yields ATGC limits of -0.18 < lambda < 0.17 and -0.46 < Delta kappa < 0.39 at the 95% confidence level, using a cut-off scale Lambda=1…
We present a measurement of the top quark pair (ttbar) production cross section in ppbar collisions at a center-of-mass energy of 1.96 TeV using 230 pb-1 of data collected by the DO detector at the Fermilab Tevatron Collider. We select events in the dilepton final states ee, emu and mumu based on kinematical properties consistent with ttbar events. For a top quark mass of 175 GeV, we measure a top pair production cross section sigma(ttbar) = 8.6 +3.2-2.7 (stat) +/-1.1 (syst) +/-0.6 (lumi) pb, in good agreement with the standard model prediction.
We search for resonant WW or WZ production using up to 5.4 fb-1 of integrated luminosity collected by the D0 experiment in Run II of the Fermilab Tevatron Collider. The data are consistent with the standard model background expectation, and we set limits on a resonance mass using the sequential standard model (SSM) W' boson and the Randall-Sundrum model graviton G as benchmarks. We exclude an SSM W' boson in the mass range 180 - 690 GeV and a Randall-Sundrum graviton in the range 300 - 754 GeV at 95% CL.
We report the results of a search for a heavy neutral gauge boson Z' decaying into the dielectron final state using data corresponding to an integrated luminosity of 5.4 fb-1 collected by the D0 experiment at the Fermilab Tevatron Collider. No significant excess above the standard model prediction is observed in the dielectron invariant-mass spectrum. We set 95% C.L. upper limits on σ(ppbar -> Z') X BR(Z' -> ee) depending on the dielectron invariant mass. These cross section limits are used to determine lower mass limits for Z' bosons in a variety of models with standard model couplings and va…
First evidence for single top quark production has recently been found by both the D0 and CDF experiments. By combining three analyses, D0 measured a cross section of 4.7 +- 1.3 pb, with a significance of 3.6 standard deviations, and CDF's matrix elements analysis measured a cross section of 3.0 +1.2 -1.1 pb, with a significance of 3.1 standard deviations. These analyses also provided the first direct measurements of the CKM matrix element, |Vtb|, without assuming unitarity. This talk briefly describes the latest single top production results from the two experiments.
Fermilab operates the world's most intense source of antiprotons. Recently various experiments have been proposed that can use those antiprotons either parasitically during Tevatron Collider running or after the Tevatron Collider finishes in about 2010. We discuss the physics goals and prospects of the proposed experiments.
We report a measurement of the diffractive structure function $F_{jj}^D$ of the antiproton obtained from a study of dijet events produced in association with a leading antiproton in $\bar pp$ collisions at $\sqrt s=630$ GeV at the Fermilab Tevatron. The ratio of $F_{jj}^D$ at $\sqrt s=630$ GeV to $F_{jj}^D$ obtained from a similar measurement at $\sqrt s=1800$ GeV is compared with expectations from QCD factorization and with theoretical predictions. We also report a measurement of the $ξ$ ($x$-Pomeron) and $β$ ($x$ of parton in Pomeron) dependence of $F_{jj}^D$ at $\sqrt s=1800$ GeV. In the re…
We present results from MiniMax (Fermilab T-864), a small test/experiment at the Tevatron designed to search for the production of disoriented chiral condensate (DCC) in $p - \bar p$ collisions at $\sqrt{s} = 1.8$ TeV in the forward direction, $\sim 3.4 < η< \sim 4.2$. Data, consisting of $1.3 \times 10^6$ events, are analyzed using the robust observables developed in an earlier paper. The results are consistent with generic, binomial-distribution partition of pions into charged and neutral species. Limits on DCC production in various models are presented.
We combine the results of searches by the CDF and D0 collaborations for a fermiophobic Higgs boson (H_f) produced via the processes WH_f, ZH_f, and vector-boson fusion in ppbar collisions at sqrt(s)=1.96 TeV at the Fermilab Tevatron collider. The analyses seek Higgs boson decays to W^+W^- and gamma gamma. With up to 8.2 fb-1 of integrated luminosity analyzed at CDF and up to 8.2 fb-1 at D0, we obtain a 95% CL lower bound on the mass of the Higgs boson in the fermiophobic Higgs model of 119 GeV/c^2.
We present first evidence for the production of single top quarks at the Fermilab Tevatron {\ppbar} collider. Both D0 and CDF experiments have measured the single top production cross section with a 3-standard-deviation significance using 0.9 fb$^{-1}$ and 2.2 fb$^{-1}$ of lepton+jets data, respectively. A direct measurement of the CKM matrix element that describes the $Wtb$ coupling is also performed for the first time.
We present results of a search for WH -> lepton neutrino b bbar production in ppbar collisions based on the analysis of 1.05 fb-1 of data collected by the D0 experiment at the Fermilab Tevatron, using a neural network for separating the signal from backgrounds. No signal-like excess is observed, and we set 95 % C.L. upper limits on the WH production cross section multiplied by the branching ratio for H->bb for Higgs boson masses between 100 and 150 GeV. For a Higgs boson mass of 115 GeV, we obtain an observed (expected) limit of 1.5 (1.4) pb, a factor of 11.4 (10.7) times larger than standard …
A direct measurement of the total decay width of the W boson G_W is presented using 350 pb-1 of data from ppbar collisions at sqrt(s) = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. The width is determined by normalizing predicted signal and background distributions to 230185 W candidates decaying to enu and munu in the transverse-mass region 50 < M_T < 90 GeV and then fitting the predicted shape to 6055 events in the high-M_T region, 90 < M_T < 200 GeV. The result is G_W = 2032 +/- 45 (stat.) +/- 57 (syst.) MeV, consistent with the standard model expectation.
We present a search for ZZ and ZW vector boson pair production in ppbar collisions at sqrt(s) = 1.96 TeV using the leptonic decay channels ZZ --> ll nu nu, ZZ --> l l l' l' and ZW --> l l l' nu. In a data sample corresponding to an integrated luminosity of 194 pb-1 collected with the Collider Detector at Fermilab, 3 candidate events are found with an expected background of 1.0 +/- 0.2 events. We set a 95% confidence level upper limit of 15.2 pb on the cross section for ZZ plus ZW production, compared to the standard model prediction of 5.0 +/- 0.4 pb.
We describe a search for the standard model Higgs boson with a mass of 105 GeV/c^2 to 145 GeV/c^2 in data corresponding to an integrated luminosity of approximately 450 pb^{-1} collected with the D0 detector at the Fermilab Tevatron ppbar collider at a center-of-mass energy of 1.96 TeV. The Higgs boson is required to be produced in association with a Z boson, and the Z boson is required to decay to either electrons or muons with the Higgs boson decaying to a bbbar pair. The data are well described by the expected background, leading to 95% confidence level cross section upper limits sigma(\ppb…
We report a set of measurements of inclusive invariant transverse momentum differential cross sections of lambda, cascade and omega hyperons reconstructed in the central region with pseudorapidity within 1 and transverse momentum up to 10 GeV/c Events are collected with a minimum-bias trigger in ppbar collisions at a center-of-mass energy of 1.96 TeV using the CDF II detector at the Tevatron Collider. As transverse momentum increases, the slopes of the differential cross sections are similar not only to each other but also to those of mesons, which could indicate a universality of the particle…
Associated production of a baryonic Z' boson with the W boson can account for the excess in Wjj production observed by the CDF collaboration at the Tevatron. We analyze other possible channels of this Z' at the Tevatron and at the LHC, including γZ' and Z Z' with the Z' -> jj. We show that the chances of confirming this baryonic Z' is better at the Tevatron than at the LHC because of the faster growing backgrounds at the LHC. Unfortunately the current systematic uncertainties of the order of 10% cannot yield any significant excess in both γZ' and Z Z' channels at the Tevatron and also at the L…
We report on a first search for production of the lightest neutral CP-even Higgs boson (h) in the next-to-minimal supersymmetric standard model, where h decays to a pair of neutral pseudoscalar Higgs bosons (a), using 4.2/fb of data recorded with the D0 detector at Fermilab. The a bosons are required to either both decay to mu^+mu^- or one to mu^+mu^- and the other to tau^+tau^-. No significant signal is observed, and we set limits on its production as functions of M_a and M_h.
Data recorded by the D0 experiment at the Fermilab Tevatron Collider are analyzed to search for neutral Higgs bosons produced in association with b quarks. The search is performed in the three-b-quark channel using multijet-triggered events corresponding to an integrated luminosity of 5.2fb-1. In the absence of any significant excess above background, limits are set on the cross section multiplied by the branching ratio in the Higgs boson mass range 90 to 300 GeV, extending the excluded regions in the parameter space of the minimal supersymmetric standard model.
We present a measurement of direct photon pair production cross sections using 4.2 fb-1 of data collected with the D0 detector at the Fermilab Tevatron proton-antiproton Collider. We measure single differential cross sections as a function of the diphoton mass, the transverse momentum of the diphoton system, the azimuthal angle between the photons, and the polar scattering angle of the photons, as well as the double differential cross sections considering the last three kinematic variables in three diphoton mass bins. The results are compared with different perturbative QCD predictions and eve…
We report a search for diphoton events with large missing transverse energy produced in ppbar collisions at sqrt(s)=1.96 TeV. The data were collected with the D0 detector at the Fermilab Tevatron Collider, and correspond to 6.3 fb-1 of integrated luminosity. The observed missing transverse energy distribution is well described by the standard model prediction, and 95% C.L. limits are derived on two realizations of theories beyond the standard model. In a gauge mediated supersymmetry breaking scenario, the breaking scale Lambda is excluded for Lambda < 124 TeV. In a universal extra dimension mo…
We present an observation for ZZ -> l+l-l'+l'- (l, l' = e or mu) production in ppbar collisions at a center-of-mass energy of sqrt(s) = 1.96 TeV. Using 1.7 fb-1 of data collected by the D0 experiment at the Fermilab Tevatron Collider, we observe three candidate events with an expected background of 0.14 +0.03 -0.02 events. The significance of this observation is 5.3 standard deviations. The combination of D0 results in this channel, as well as in ZZ -> l+l-nunubar, yields a significance of 5.7 standard deviations and a combined cross section of sigma(ZZ) = 1.60 +/- 0.63 (stat.) +0.16 -0.17 (sy…
We present a measurement of the top quark pair ttbar production cross section in ppbar collisions at a center-of-mass energy of 1.96 TeV using 230 pb**{-1} of data collected by the DO detector at the Fermilab Tevatron Collider. We select events with one charged lepton (electron or muon), large missing transverse energy, and at least four jets, and extract the ttbar content of the sample based on the kinematic characteristics of the events. For a top quark mass of 175 GeV, we measure sigma(ttbar) = 6.7 {+1.4-1.3} (stat) {+1.6- 1.1} (syst) +/-0.4 (lumi) pb, in good agreement with the standard mo…
