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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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917 records · Page 51
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DOE OSTI2010

Highlights of Current Higgs Boson Searches

Over the last years the Tevatron Run-II has extended several limits on Higgs boson masses and coupling which were pioneered during the LEP accelerator operation between 1989 and 2000. Higgs boson searches will also be at the forefront of research at the LHC. This review concisely discusses the experimental constraints set by the CDF and D0 collaborations in summer 2010 at the beginning of the LHC era. Model-independent and model-dependent limits on Higgs boson masses and couplings have been set and interpretations are discussed both in the Standard Model and in extended models. Recently, the Tevatron has extended the excluded SM Higgs boson mass range (158-175 GeV) beyond the LEP limit at 95% CL. The experimental sensitivities are estimated for the completion of the Tevatron programme.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Diboson Production at the Tevatron

Here we summarize the recent measurements of the diboson production cross sections and limits on trilinear gauge boson couplings using 1-5 fb{sup -1} of Tevatron data collected by the CDF and D0 detectors. These results are the most precise to date from a hadron collider.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Updated Search for the Flavor-Changing Neutral-Current Decay $D^0 \to \mu^+ \mu^-$

We report on a search for the flavor-changing neutral-current decay D{sup 0} {yields} {mu}{sup +}{mu}{sup -} in p{bar p} collisions at {radical}s = 1.96TeV using 360 pb{sup -1} of integrated luminosity collected by the CDF II detector at the Fermilab Tevatron collider. A displaced vertex trigger selects long-lived D{sup 0} candidates in the {mu}{sup +}{mu}{sup -}, {pi}{sup +}{pi}{sup -}, and K{sup -}{pi}{sup +} decay modes. We use the Cabibbo-favored D{sup 0} {yields} K{sup -}{pi}{sup +} channel to optimize the selection criteria in an unbiased manner, and the kinematically similar D{sup 0} {yields} {pi}{sup +}{pi}{sup -} channel for normalization. We set an upper limit on the branching fraction {Beta}(D{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 2.1 x 10{sup -7} (3.0 x 10{sup -7}) at the 90% (95%) confidence level.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Higgs searches at the Tevatron

The search for the Standard Model Higgs boson in p{bar p} collisions at 1.96 TeV performed by CDF and D0 collaborations at the Tevatron collider is reported in this paper. The Higgs candidate events are reconstructed using different final states in order to optimize the sensitivity in the full range of the Higgs mass. The presented results use different statistical samples collected by the Tevatron up to 5.9 fb{sup -1}. Combining the most updated limits provided by the two experiments for all the final states analyzed, the Standard Model Higgs boson is excluded at 95% C.L. in the mass range 158-175 GeV/c{sup 2}, in good agreement with the prediction for the analyzed data sample.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Multi-boson production

The studies of the diboson production in p{bar p} collisions at 1.96 TeV performed by CDF and D0 collaborations at the Tevatron collider are reported in this paper. The diboson events are identified by means of both leptonic and semi-leptonic final states. The presented results use different statistical samples collected by the Tevatron up to 4.8 fb{sup -1}. Measured production cross sections are in good agreement with Standard Model predictions and the limits on the anomalous triple gauge boson couplings are competitive with those measured by experiments at the Large Electron-Positron collider (LEP).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Single top quark production and Vtb at the Tevatron

Single top quark production via the electroweak interaction was observed by the D0 and CDF collaborations at the Tevatron proton-antiproton collider at Fermilab. Multivariate analysis techniques are employed to extract the small single top quark signal. The combined Tevatron cross section is 2.76{sub -0.47}{sup +0.58} pb. This corresponds to a lower limit on the CKM matrix element |V{sub tb}| of 0.77. Also reported are measurements of the t-channel cross section, the top quark polarization in single top quark events, and limits on gluon-quark flavor-changing neutral currents and W{prime} boson production.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Bs decays at the Tevatron

The authors present measurements of the branching ratio and of the polarization amplitudes in charmless B{sub s} {yields} {phi}{phi} decays using data corresponding to 2.9 fb{sup -1} of integrated luminosity, collected by the CDF experiment at the Tevatron. The branching ratio in B{sub s} {yields} {phi}{phi} decays is measured relative to the normalization mode B{sub s} {yields} J/{Psi}{phi} be {Beta}(B{sub s} {yields} {phi}{phi})/{Beta}(B{sub s} {yields} J/{Psi}{phi}) = [1.78 {+-} 0.14(stat) {+-} 0.20(syst)] x 10{sup -2}. Using the experimental value of {Beta}(B{sub s} {yields} J/{Psi}{phi}) they determine the B{sub s} {yields} {phi}{phi} branching ratio {Beta}(B{sub s} {yields} {phi}{phi}) = 2.40 {+-} 0.21(stat) {+-} 0.27(syst) {+-} 0.82(BR) x 10{sup -5}. The polarization fractions are measured for the first time in this analysis and found to be: |A{sub 0}|{sup 2} = 0.348 {+-} 0.041(stat) {+-} 0.021(syst); |A{sub {parallel}}|{sup 2} = 0.287 {+-} 0.043(stat) {+-} 0.011(syst); and |A{sub {perpendicular}}|{sup 2} = 0.365 {+-} 0.044(stat) {+-} 0.027(syst).

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Top Quark Mass Measurement in the Lepton + Jets Channel Using a Matrix Element Method and \textit{in situ} Jet Energy Calibration

A precision measurement of the top quark mass m{sub t} is obtained using a sample of t{bar t} events from p{bar p} collisions at the Fermilab Tevatron with the CDF II detector. Selected events require an electron or muon, large missing transverse energy, and exactly four high-energy jets, at least one of which is tagged as coming from a b quark. A likelihood is calculated using a matrix element method with quasi-Monte Carlo integration taking into account finite detector resolution and jet mass effects. The event likelihood is a function of m{sub t} and a parameter {Delta}{sub JES} used to calibrate the jet energy scale in situ. Using a total of 1087 events, a value of m{sub t} = 173.0 {+-} 1.2 GeV/c{sup 2} is measured.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Evidence for high mass exclusive dijet production in the D0 experiment

Exclusive diffractive Higgs boson production is an interesting process which could be studied at the Large Hadron Collider. While the cross section for the Higgs boson production at the Fermilab Tevatron Collider is too low for this channel, it is important to check if the class of exclusive diffraction events exists. We present the evidence for the high mass exclusive dijet production in the D0 experiment. Hard diffractive processes are usually described by the exchange of a colorless object called Pomeron. In diffractive hadron hadron collisions, the hadrons will exchange the Pomeron and either one or both hadrons will not dissolve. The events are identified by either a presence of a large forward region of the detector devoid of any activity (rapidity gap) or by a tagging of the intact beam hadron(s). A subset of diffractive events is called exclusive when the whole Pomeron energy is used to produce the diffractive state, i.e there are no Pomeron remnants. Exclusive diffractive production (EDP) of the Higgs boson or any other new final state X pp {yields} p + X + p has been recently proposed as a search channel at the LHC. The cross section for the Higgs boson production is too low at the Tevatron (0.2fb is predicted for a Higgs boson mass of 120 GeV), but it is important to check if this class of events exists in this kinematic region. The CDF Collaboration has recently confirmed the existence of EDP in several channels. In this report, we present the evidence for the exclusive production of high dijet invariant mass events, i.e. a dijet event accompanied by large rapidity gaps on both sides of the calorimeter.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2010

Improved Search for a Higgs Boson Produced in Association with Z->l+l- in proton antiproton Collisions at sqrt(s) = 1.96 TeV

We present a search for the standard model Higgs boson produced with a Z boson in 4.1 fb{sup -1} of data collected with the CDF II detector at the Tevatron. In events consistent with the decay of the Higgs boson to a bottom-quark pair and the Z boson to electrons or muons, we set 95% credibility level upper limits on the ZH production cross section times the H {yields} b{bar b} branching ratio. Improved analysis methods enhance signal sensitivity by 20% relative to previous searches beyond the gain due to the larger data sample. At a Higgs boson mass of 115 GeV/c{sup 2} we set a limit of 5.9 times the standard model value.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of the D + -meson production cross section at low transverse momentum in p p ¯ collisions at s = 1.96 TeV

We report on a measurement of the D + -meson production cross section as a function of transverse momentum (p T ) in proton-antiproton (p$\bar{p}$) collisions at 1.96 TeV center-of-mass energy, using the full data set collected by the Collider Detector at Fermilab in Tevatron Run II and corresponding to 10 fb -1 of integrated luminosity. We use D + →K - π + π + decays fully reconstructed in the central rapidity region |y|<1 with transverse momentum down to 1.5 GeV/c, a range previously unexplored in p$\bar{p}$ collisions. Inelastic p$\bar{p}$ scattering events are selected online using minimally biasing requirements followed by an optimized offline selection. The K - π + π + mass distribution is used to identify the D + signal, and the D + transverse impact-parameter distribution is used to separate prompt production, occurring directly in the hard-scattering process, from secondary production from b-hadron decays. We obtain a prompt D + signal of 2950 candidates corresponding to a total cross section σ(D + ,1.5 T <14.5 GeV/c,|y|<1)=71.9±6.8(stat)±9.3(syst) μb. While the measured cross sections are consistent with theoretical estimates in each p T bin, the shape of the observed p T spectrum is softer than the expectation from quantum chromodynamics. The results are unique in p$\bar{p}$ collisions and can improve the shape and uncertainties of future predictions.

(K-↗
NASA NTRS2022

Irrigation Characterization Improved by the Direct Use of SMAP Soil Moisture Anomalies Within a Data Assimilation System

Prior soil moisture data assimilation (DA) efforts to incorporate human management features such as agricultural irrigation has only shown limited success. This is partly due to the fact that observational rescaling approaches for bias correction used in soil moisture DA systems are less effective when unmodeled processes such as irrigation are the dominant source of systematic biases. In this article, we demonstrate an alternative approach, i.e. anomaly correction for overcoming this limitation. Unlike the rescaling approaches, the proposed method does not scale remote sensing soil moisture retrievals to the model climatology, but it extracts the temporal variability information from the retrievals. The study demonstrates this approach through the assimilation of soil moisture retrievals from the Soil Moisture Active Passive mission into the Noah land surface model. The results demonstrate that DA using the anomaly correction method can better capture the effect of irrigation on soil moisture in agricultural areas while providing comparable performance to the DA integrations using rescaling approaches in non-irrigated areas. These findings emphasize the need to reduce inconsistencies between remote sensing and the models so that assimilation methods can employ information from remote sensing more directly to develop representations of unmodeled processes such as irrigation.

soil moisture↗
NASA NTRSDate not supplied

Creating A Consistent Historical NASA POWER Solar Radiation Dataset to Support Renewable Energy, Building Energy Efficiency and Agro-Climatology Decisions

Prediction of Worldwide Energy Resources (POWER) project provides irradiance dataset to support renewable energy, building energy efficiency and agricultural needs. These datasets are derived from Global Energy and Water Cycle Experiment Surface Radiation Budget (GEWEX SRB) and Clouds and the Earth’s Radiant Energy System (CERES SYN1Deg). A systematic bias has been reported between these two datasets for the years with overlapping observations. For obtaining a consistent climate data record spanning the entire time record of observations, it is crucial to understand and remove the bias in the irradiance dataset. Inconsistency in solar radiation data can lead to inaccurate conclusions about solar energy potential and obscure real trends in solar radiation patterns that would impact energy availability assessments. In this study, we adapt quantile mapping approach to remove the systematic bias and to improve reliability of shortwave and longwave irradiance data. We present a validation of the bias corrected data against ground truth. For each 1° latitude and 1° longitude grid box across the globe, we match the CDFs of the reference dataset (CERES SYN1Deg) to that of the SRB dataset, thereby, adjusting the irradiance values to match the empirical distribution of two different measurements. The performance of quantile mapping is evaluated by using the metrics such as Mean Absolute Deviation (MAD). The results indicate that the quantile mapping significantly improves the accuracy and reliability of solar irradiance dataset especially for the weather conditions associated with high cloud cover and extreme irradiance values. The initial range of MAD for the studied sites for daily data was 4 to 19 Wm-2. After correction these reduced to 3 to 7 Wm-2. The findings from this study have important implications for solar energy system design, agricultural planning, and climate modeling community. Reducing the inconsistency and biases in solar irradiance dataset can enable better planning and operation of solar energy systems, leading to increased efficiency and cost-effectiveness. Additionally, this work also contributes to the statistical post-processing techniques in the renewable energy domain and highlights the potential of historical and near-real-time NASA POWER dataset as a valuable resource for solar energy research and applications.

POWER↗
DOE OSTI2014

Controlling O&M Costs of Advanced SMRs using Prognostics and Enhanced Risk Monitoring

Advanced small modular reactors (AdvSMRs) can contribute to safe, sustainable, and carbon-neutral energy production. The economics of small reactors (including AdvSMRs) will be impacted by the reduced economy-of-scale savings when compared to traditional light water reactors. The most significant controllable element of the day-to-day costs involves operations and maintenance (O&M). Enhancing affordability of AdvSMRs through technologies that help control O&M costs will be critical to ensuring their practicality for wider deployment.A significant component of O&M costs is the management and mitigation of degradation of components due to their impact on planning maintenance activities and staffing levels. Technologies that help characterize real-time risk of failure of key components are important in this context. Given the possibility of frequently changing AdvSMR plant configurations, approaches are needed to integrate three elements – advanced plant configuration information, equipment condition information, and risk monitors – to provide a measure of risk that is customized for each AdvSMR unit and support real-time decisions on O&M. This article describes an overview of ongoing research into diagnostics/prognostics and enhanced predictive risk monitors (ERM) for this purpose.

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS↗