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At least 451 records · Page 25
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DOE OSTI2011

Searches for Fourth Generation Fermions

We present the results from searches for fourth generation fermions performed using data samples collected by the CDF II and D0 Detectors at the Fermilab Tevatron p{bar p} collider. Many of these results represent the most stringent 95% C. L. limits on masses of new fermions to-date. A fourth chiral generation of massive fermions with the same quantum numbers as the known fermions is one of the simplest extensions of the SM with three generations. The fourth generation is predicted in a number of theories, and although historically have been considered disfavored, stands in agreement with electroweak precision data. To avoid Z {yields} {nu}{bar {nu}} constraint from LEP I a fourth generation neutrino {nu}{sub 4} must be heavy: m({nu}{sub 4}) > m{sub Z}/2, where m{sub Z} is the mass of Z boson, and to avoid LEP II bounds a fourth generation charged lepton {ell}{sub 4} must have m({ell}{sub 4}) > 101 GeV/c{sup 2}. At the same time due to sizeable radiative corrections masses of fourth generation fermions cannot be much higher the current lower bounds and masses of new heavy quarks t' and b' should be in the range of a few hundred GeV/c{sup 2}. In the four-generation model the present bounds on the Higgs are relaxed: the Higgs mass could be as large as 1 TeV/c{sup 2}. Furthermore, the CP violation is significantly enhanced to the magnitude that might account for the baryon asymmetry in the Universe. Additional chiral fermion families can also be accommodated in supersymmetric two-Higgs-doublet extensions of the SM with equivalent effect on the precision fit to the Higgs mass. Another possibility is heavy exotic quarks with vector couplings to the W boson Contributions to radiative corrections from such quarks with mass M decouple as 1/M{sup 2} and easily evade all experimental constraints. At the Tevatron p{bar p} collider 4-th generation chiral or vector-like quarks can be either produced strongly in pairs or singly via electroweak production, where the latter can be enhanced for vector-like quarks. In the following we present searches for both pair and single production of heavy quarks performed by CDF and D0 Collaborations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

D0 - D0bar Mixing: An Overview

Recently, the B factory experiments BABAR and Belle as well as the CDF collaboration found evidence for mixing in the D meson system. The current status (beginning of summer 2008) of the experimental results of D{sup 0} mixing is summarized. In this paper, we present an overview of D{sup 0} mixing. After an introduction to the charm mixing phenomenology and analysis techniques, results of the mixing parameters and CP violation as related to mixing are summarized. They are obtained from hadronic two-body, multi-body final states and from quantum correlated D{sup 0} decays of the experiments BABAR, Belle, Cleo and CDF. Mixing results from semileptonic D{sup 0} decays can be found elsewhere.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Test of QCD in multijet final states at the Tevatron

In this contribution, some of the recent QCD results on jet production from the CDF and D0 experiments in Run II of the Tevatron are discussed. In particular, results include cross section measurements for dijet and trijet production, study of jet substructure and measurements of W/Z+jets cross sections. The measurements are compared with the theoretical predictions. The QCD program at the Tevatron proton-antiproton collider revolves around the jet physics. Jets are collimated sprays of hadrons generated by the fragmentation of partons originating from the hard scattering. The measurements of jets production cross section at the Tevatron provide stringent test of perturbative QCD predictions, information on the strong coupling constant, {alpha}s, and constraints on proton parton distribution functions, PDFs. The deviations from the pQCD predictions could translate into a hint of new physics. In addition, these processes form sizable backgrounds to both, the Standard Model (SM) and beyond SM physics processes. Therefore, good understanding of jets production is essential to perform precise physics measurements or searches for new physics phenomena. In this contribution, a review of some recent QCD results from the CDF [1] and D0 [2] experiments is presented. Various analyses use proton-antiproton collision data from the Fermilab Tevatron at the center of mass energy {radical}s = 1.96 TeV corresponding to integrated luminosities of 0.7 fb{sup -1} to 8 fb{sup -1}. The results are corrected for the experimental effects and presented at the 'particle level'. The theory predictions are corrected for the hadronization and underlying effects which are obtained from the parton shower Monte Carlo (MC) simulations.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

Heavy Hadron Spectroscopy and Production at Tevatron

Using data from p{bar p} collisions at {radical}s = 1.96 TeV recorded by the CDFII and D0 detectors at the Fermilab Tevatron, we present recent results on charm and bottom hadrons. The most recent CDF results on properties of the four bottom baryon resonant states {Sigma}{sub b}{sup (*)-}, {Sigma}{sub b}{sup (*)+}. New results on exotic {Upsilon}(4140) state observed by CDF are also reported. A precise measurement of production rates of the lowest lying bottom baryon, {Lambda}{sub b}{sup 0}, produced in the D0 detector is presented.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

New Measurements of Upsilon Spin Alignment at the Tevatron

We describe a new analysis of {Upsilon}(nS) {yields} {mu}{sup +}{mu}{sup -} decays collected in p{bar p} collisions with the CDF II detector at the Fermilab Tevatron. This analysis measures the angular distributions of the final state muons in the {Upsilon} rest frame, providing new information about {Upsilon} production polarization. We find the angular distributions to be nearly isotropic up to {Upsilon} p{sub T} of 40 GeV/c, consistent with previous measurements by CDF, but inconsistent with results obtained by the D0 experiment. The results are compared with recent NLO calculations based on color-singlet matrix elements and non-relativistic QCD with color-octet matrix elements.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

W Mass results from Tevatron and LHC

Most recent results of W boson mass measurements from Tevatron experiments (CDF and D0) in p{bar p} collisions at {radical}s = 1.96 GeV are reported, using 0.2 fb{sup -1} and 1.0 fb{sup -1} data collected at CDF and D0, respectively. The measurements of W boson properties at LHC experiments (ATLAS, CMS, and LHCb) in pp collisions at {radical}s = 7 TeV, using data collected before Summer 2011, are presented. These measurements are essential at the preparation stage of the W boson mass measurements at LHC. Challenges for W mass measurement at the LHC in comparison with the Tevatron are outlined. Prospects for W mass precision with upcoming measurements and its implications are discussed.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

SUSY searches at the Tevatron

The Tevatron collider has provided the CDF and D0 collaborations with large datasets as input to a rich program of physics beyond the standard model. The results presented here are from recent searches for SUSY particles using up to 6 fb{sup -1} of data. Supersymmetry (SUSY) [1] is one of the most favored theories beyond the standard model (SM). Each SM particle is associated to a sparticle whose spin differs by one half unit. This boson-fermion symmetry is obviously broken by some unknown mechanism. Even in the minimal supersymmetric extension of the SM (MSSM [2]) there are a large number of free parameters. To reduce this number one can introduce new assumptions on the symmetry breaking mechanism and build models based on minimal supergravity (as mSUGRA [3]) or on a Gauge Mediated Symmetry Breaking scenario (GMSB [4]), a top-down approach. Another possibility is to make phenomenological assumptions to reduce the number of particles accessible to the experiment while keeping some of the properties of the above models (bottom-up approach). As the sparticles are heavy, to produce them one has to make collisions at the highest center of mass energy. The Tevatron was the best place for discovery until the start of LHC. In the near term, Tevatron experiments and their large datasets remain competitive in areas like production of third generation squarks and of non-coloured sparticles. I will report on recent results from the CDF and D0 collaborations, assuming R-parity is conserved, i.e the sparticles are produced in pairs, and the lightest of them (LSP) is stable, neutral, weakly interacting, and detected as missing transverse energy, E{sub T}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2011

A new concept of vertically integrated pattern recognition associative memory

Hardware-based pattern recognition for fast triggering on particle tracks has been successfully used in high-energy physics experiments for some time. The CDF Silicon Vertex Trigger (SVT) at the Fermilab Tevatron is an excellent example. The method used there, developed in the 1990's, is based on algorithms that use a massively parallel associative memory architecture to identify patterns efficiently at high speed. However, due to much higher occupancy and event rates at the LHC, and the fact that the LHC detectors have a much larger number of channels in their tracking detectors, there is an enormous challenge in implementing fast pattern recognition for a track trigger, requiring about three orders of magnitude more associative memory patterns than what was used in the original CDF SVT. Scaling of current technologies is unlikely to satisfy the scientific needs of the future, and investments in transformational new technologies need to be made. In this paper, we will discuss a new concept of using the emerging 3D vertical integration technology to significantly advance the state-of-the-art for fast pattern recognition within and outside HEP. A generic R and D proposal based on this new concept, with a few institutions involved, has recently been submitted to DOE with the goal to design and perform the ASIC engineering necessary to realize a prototype device. The progress of this R and D project will be reported in the future. Here we will only focus on the concept of this new approach.

43 PARTICLE ACCELERATORS↗
DOE OSTI2012

Recent heavy flavor results from the Tevatron

The CDF and D0 experiments at the Tevatron p{bar p} collider have pioneered and established the role of flavor physics in hadron collisions. A broad program is now at its full maturity. We report on three new results sensitive to physics beyond the standard model, obtained using the whole CDF dataset: a measurement of the difference of CP asymmetries in K{sup +}K{sup -} and {pi}{sup +}{pi}{sup -} decays of D{sup 0} mesons, new bounds on the B{sub s}{sup 0} mixing phase and on the decay width difference of B{sub s}{sup 0} mass-eigenstates, and an update of the summer 2011 search for B{sub (s)}{sup 0} mesons decaying into pairs of muons. Finally, the D0 confirmation of the observation of a new hadron, the {chi}{sub b}(3P) state, is briefly mentioned.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Recent Results of Top Quark Physics from the Tevatron

Twenty years after its discovery in 1995 by the CDF and D0 collaborations at the Tevatron proton-antiproton collider at Fermilab, the top quark still undergoes intensive studies at the Tevatron and the LHC at CERN. In this article, recent top quark physics results from CDF and D0 are reported. In particular, measurements of single top quark and double top quark production, the $t\bar{t}$ forward-backward asymmetry and the top quark mass are discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Top Quark Pair Production Cross Section at the Tevatron

The top quark, discovered in 1995 by the CDF and D0 collaborations at the Tevatron proton antiproton collider at Fermilab, has undergone intense studies in the last 20 years. Currently, CDF and D0 converge on their measurements of top-antitop quark production cross sections using the full Tevatron data sample. In these proceedings, the latest results on inclusive and differential measurements of top-antitop quark production cross sections at the Tevatron are reported.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Measurements of top quark production and properties at the Tevatron

In this letter, we summarize the latest results of the top-quark production and properties at the Tevatron. We do not include results of the top-quark mass and single top-quark production as they were presented in separate talks. The results of the measurements are mostly consistent with the standard-model predictions. However, by looking at the production asymmetry measured by CDF, one can see a discrepancy in both, $t\bar{t}$ inclusive and lepton-based measurements. D\O\ results of production asymmetry are compatible with the standard-model predictions as well as with the CDF results.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Top Quark Mass Measurements at the Tevatron

Since the discovery of the top quark in 1995 by the CDF and D0 collaborations at the Fermilab Tevatron proton antiproton collider, precise measurements of its mass are ongoing. Using data recorded by the D0 and CDF experiment, corresponding to up to the full Tevatron data sample, top quark mass measurements performed in different final states using various extraction techniques are presented in this article. The recent Tevatron top quark mass combination yields m_t=173.20 +-0.87 GeV. Furthermore, measurements of the top antitop quark mass difference from the Tevatron are discussed.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Probabilistic Wind Power Ramp Forecasting Based on a Scenario Generation Method: Preprint

Wind power ramps (WPRs) are particularly important in the management and dispatch of wind power, and they are currently drawing the attention of balancing authorities. With the aim to reduce the impact of WPRs for power system operations, this paper develops a probabilistic ramp forecasting method based on a large number of simulated scenarios. An ensemble machine learning technique is first adopted to forecast the basic wind power forecasting scenario and calculate the historical forecasting errors. A continuous Gaussian mixture model (GMM) is used to fit the probability distribution function (PDF) of forecasting errors. The cumulative distribution function (CDF) is analytically deduced. The inverse transform method based on Monte Carlo sampling and the CDF is used to generate a massive number of forecasting error scenarios. An optimized swinging door algorithm is adopted to extract all the WPRs from the complete set of wind power forecasting scenarios. The probabilistic forecasting results of ramp duration and start time are generated based on all scenarios. Numerical simulations on publicly available wind power data show that within a predefined tolerance level, the developed probabilistic wind power ramp forecasting method is able to predict WPRs with a high level of sharpness and accuracy.

17 WIND ENERGY↗
DOE OSTI2013

Single Top Quark Production at the Tevatron

While the heaviest known elementary particle, the top quark, has been discovered in 1995 by the CDF and D0 collaborations in ttbar events, it took 14 more years until the observation of single top quark production. In this article, we discuss recent studies of single top quark production by the CDF and D0 collaborations at the Tevatron. In particular, we present the measurement of single top quark s- and t-channel production combined, the first observation of t-channel production, the simultaneous measurement of s- and t-channel production cross sections as well as the extraction of the CMK matrix element |Vtb}|.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Top Quark Properties at Tevatron

The latest CDF and D0 experiment measurements of the top quark properties except the top quark mass are presented. The final combination of the CDF and D0 forward-backward asymmetry measurements is shown together with the D0 measurements of the inclusive top quark pair cross-section as well as the top quark polarization.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

High Mass Higgs Boson Searches at the Tevatron

We present results from CDF and D0 on direct searches for high mass standard model (SM) Higgs boson (H) in ppbar collisions at the Fermilab Tevatron at \sqrt(s) = 1.96 TeV. Compared to previous Higgs boson Tevatron combinations, more data and new channels (H -> W+W- -> lnujj, H -> WW -> l+tau + X and trilepton final states) have been added. Most previously used channels have been reanalyzed to gain sensitivity. Analyzing 5.9 fb^-1 of data at CDF, and 5.4-6.7 fb^-1 at D0, the combination excludes with 95% C.L. a standard model Higgs boson in the mass range of m_H = 158-175 GeV/c2.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2012

On-line maintenance methodology development and its applications

With the increasing economic pressures being faced and the potential for shortening outage times under the conditions of deregulated electricity markets in the world, licensees are motivated to get an increasing amount of the on-line maintenance (OLM). The benefits of the OLM includes increased system and plant reliability, reduction of plant equipment and system material condition deficiencies that could adversely impact operations, and reduction of work scope during plant refueling outages. In Korea, allowance guidelines of risk assessment is specified in the safety regulation guidelines 16.7 and 16.8 of the Korea Inst. of Nuclear Safety (KINS), which is 'General guidelines of Risk-informed application for requesting permission of changes' and 'Requesting permission of changes of Risk-informed application for Technical Specification'. We select the emergency diesel generator (EDG) of the Ulchin unit 3 and 4 for risk assessment analysis by applying configuration changes. The EDG which has plant safety level IE belongs to on-site standby power (A, B train EDG) in electric distribution system. The EDG is important component because it should maintain standby status during plant is operating, therefore we select the EDG for target component of risk assessment analysis. The risk assessment is limited to CDF. The risk assessment is performed by using AIMS-PSA Release2. We evaluate CDF by applying the configuration changes with some assumptions. Evaluation of the full power operation and Low power/Shut down operation was performed. This study has been performed for introducing a methodology and performing risk assessment. (authors)

22 GENERAL STUDIES OF NUCLEAR REACTORS↗