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Search for large extra dimensions in final states containing one photon or jet and large missing transverse energy produced in p anti-p collisions at s**(1/2) = 1.96-TeV
The authors present the results of searches for large extra dimensions in samples of events with large missing transverse energy E{sub T} and either a photon or a jet produced in p{bar p} collisions at {radical}s = 1.96 TeV collected with the CDF II detector. For {gamma} + E{sub T} and jet + E{sub T} candidate samples corresponding to 2.0 fb{sup -1} and 1.1 fb{sup -1} of integrated luminosity respectively, they observe good agreement with standard model expectations and obtain a combined lower limit on the fundamental parameter of the large extra dimensions model, M{sub D}, as a function of the number of extra dimensions in the model.
Date:
July 1, 2008
Creator:
Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Object Type:
Article
System:
The UNT Digital Library
Search for the Higgs boson produced with $Z \to \ell^+\ell^-$ in $p\bar{p}$ collisions at $\sqrt{s}=$ 1.96 TeV
The authors present a search for the Higgs boson in the process q{bar q} {yields} ZN {yields} {ell}{sup +}{ell}{sup -} b{bar b}. The analysis uses an integrated luminosity of 1 fb{sup -1} of p{bar p} collisions produced at {radical}s = 1.96 TeV and accumulated by the upgraded Collider Detector at Fermilab (CDF II). They employ artificial neural networks both to correct jets mismeasured in the calorimeter, and to distinguish the signal kinematic distributions from those of the background. They see no evidence for Higgs boson production, and set 95% CL upper limits on {sigma}{sub ZH} {center_dot} {Beta}(H {yields} b{bar b}), ranging from 1.5 pb to 1.2 pb for a Higgs mass (m{sub H}) of 110 to 150 GeV/c{sup 2}.
Date:
July 1, 2008
Creator:
Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Object Type:
Article
System:
The UNT Digital Library
Parameterizing the power spectrum: Beyond the truncated Taylor expansion
The power spectrum is traditionally parameterized by a truncated Taylor series: ln P(k) = ln P{sub *} + (n{sub *} - 1) ln(k/k{sub *}) + 1/2 n'{sub *} ln{sup 2} (k/k{sub *}). It is reasonable to truncate the Taylor series if |n'{sub *} ln(k/k{sub *})| << |n{sub *} - 1|, but it is not if |n'{sub *} ln(k/k{sub *})| {approx}> |n{sub *} - 1|. We argue that there is no good theoretical reason to prefer |n'{sub *}| << |n{sub *} - 1|, and show that current observations are consistent with |n*{sub *} ln(k/k{sub *})| {approx} |n{sub *} - 1| even for |ln(k/k{sub *})| {approx} 1. Thus, there are regions of parameter space, which are both theoretically and observationally relevant, for which the traditional truncated Taylor series parameterization is inconsistent, and hence it can lead to incorrect parameter estimations. Motivated by this, we propose a simple extension of the traditional parameterization, which uses no extra parameters, but that, unlike the traditional approach, covers well motivated inflationary spectra with |n'{sub *}| {approx} |n{sub *} - 1|. Our parameterization therefore covers not only standard-slow-roll inflation models but also a much wider class of inflation models. We use this parameterization to perform a likelihood …
Date:
July 1, 2005
Creator:
Abazajian, Kevork; Kadota, Kenji & Stewart, Ewan D.
Object Type:
Article
System:
The UNT Digital Library
Search for pair production of first-generation leptoquarks in p pbar collisions at sqrt(s)=1.96 TeV
A search for pair production of first-generation leptoquarks (LQ) is performed with data collected by the D0 experiment in p{bar p} collisions at {radical}s = 1.96 TeV at the Fermilab Tevatron Collider. In a sample of data corresponding to {approx} 1 fb{sup -1} the search has been performed on the final states with two electrons and two jets or one electron, two jets and missing transverse energy. We find our data consistent with standard model expectations. The results are combined with those found in a previous analysis of events with two jets and missing transverse energy to obtain scalar LQ mass limits. We set 95% C.L. lower limits on a scalar LQ mass of 299 GeV, 284 GeV and 216 GeV for {beta} = 1, {beta} = 0.5 and {beta} = 0.02 respectively, where {beta} is the LQ branching ratio in the eq channel. This improves the results obtained with a lower luminosity sample from Run II of the Tevatron. Lower limits on vector LQ masses with different couplings from 357 GeV to 464 GeV for {beta} = 0.5 are also set using this analysis.
Date:
July 1, 2009
Creator:
Abazov, : V.
Object Type:
Article
System:
The UNT Digital Library
The Upgraded D0 detector
The D0 experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid-argon calorimeters and central muon detector, remaining from Run I, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to D0.
Date:
July 1, 2005
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, D. L.; Adams, M. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of semileptonic branching fractions of B mesons to narrow D** states
None
Date:
July 1, 2005
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the electron charge asymmetry in p anti-p ---> W + X ---> e nu + X events at s**(1/2) = 1.96-TeV
None
Date:
July 1, 2008
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for associated Higgs boson production WH ---> WWW* ---> l+- nu l-prime+- nu-prime + X in p anti-p collisions at s**(1/2) = 1.96-TeV
The authors present a search for associated Higgs boson production in the process p{bar p} {yields} WH {yields} WWW* {yields} {ell}{sup {+-}}{nu} {ell}{prime}{sup {+-}} {nu}{prime} + X in final states containing two like-sign isolated electrons or muons (e{sup {+-}}e{sup {+-}}, e{sup {+-}} {mu}{sup {+-}}, or {mu}{sup {+-}} {mu}{sup {+-}}). The search is based on D0 Run II data samples corresponding to integrated luminosities of 360-380 pb{sup -1}. No excess is observed over the predicted standard model background. They set 95% C.L. upper limits on {sigma}(p{bar p} {yields} WH) x Br(H {yields} WW*) between 3.2 and 2.8 pb for Higgs masses from 115 to 175 GeV.
Date:
July 1, 2006
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for Bs --> mu+ mu- at D0
We report results from a search for the decay B{sup 0}{sub S} {yields} {mu}{sup +}{mu}{sup -} using 1.3 fb{sup -1} of p{bar p} collisions at {radical}s = 1.96 TeV collected by the D0 experiment at the Fermilab Tevatron Collider. We find two candidate events, consistent with the expected background of 1.24 {+-} 0.99, and set an upper limit on the branching fraction of B(B{sub S}{sup 0} {yields} {mu}{sup +}{mu}{sup -}) < 1.2 x 10{sup -7} at the 95% C.L.
Date:
July 1, 2007
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for scalar leptoquarks in the acoplanar jet topology in p anti-p collisions at s**(1/2) = 1.96-TeV
A search for leptoquarks has been performed in 310 pb{sup -1} of data from p{bar p} 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.
Date:
July 1, 2006
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for the lightest scalar top quark in events with two leptons in p anti-p collisions at s**(1/2) = 1.96-TeV
Data collected by the D0 detector at a p{bar p} center-of-mass energy of 1.96 TeV at the Fermilab Tevatron Collider have been used to search for pair production of the lightest supersymmetric partner of the top quark decaying into b{ell}{bar {nu}}. The search is performed in the {ell}{ell}{prime} = e{mu} and {mu}{mu} final states. No evidence for this process has been found in data samples of approximately 400 pb{sup -1}. The domain in the [M({bar t}{sub 1}),M({bar {nu}})] plane excluded at the 95% C.L. is substantially extended by this search.
Date:
July 1, 2007
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for the Standard Model Higgs Boson in the p anti-p ---> ZH ---> nu anti-nu b anti-b channel
We report a search for the standard model (SM) Higgs boson based on data collected by the D0 experiment at the Fermilab Tevatron Collider, corresponding to an integrated luminosity of 260 pb{sup -1}. We study events with missing transverse energy and two acoplanar b-jets, which provide sensitivity to the ZH production cross section in the {nu}{bar {nu}}B{bar b} channel and to WH production, when the lepton from the W {yields} {ell}{nu} decay is undetected. The data are consistent with the SM background expectation, and we set 95% C.L. upper limits on {sigma}(p{bar p} {yields} ZN/WH) x B(H {yields} b{bar b}) from 3.4/8.3 to 2.5/6.3 pb, for Higgs masses between 105 and 135 GeV.
Date:
July 1, 2006
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type:
Article
System:
The UNT Digital Library
Search for W-prime boson production in the top quark decay channel
We present a search for the production of a new heavy gauge boson W' that decays to a top quark and a bottom quark. We have analyzed 230 pb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron collider at a center-of-mass energy of 1.96 TeV. No significant excess of events is found in any region of the final state invariant mass distribution. We set upper limits on the production cross section of W bosons at the 95% confidence level for several different W' boson masses. We exclude masses below 610 GeV for a W' boson with standard-model-like couplings, below 630 GeV for a W' boson with right-handed couplings that is allowed to decay to both leptons and quarks, and below 670 GeV for a W' boson with right-handed couplings that is only allowed to decay to quarks.
Date:
July 1, 2006
Creator:
Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of the t-channel single top quark production cross section
The D0 collaboration reports direct evidence for electroweak production of single top quarks through the t-channel exchange of a virtual W boson. This is the first analysis to isolate an individual single top quark production channel. We select events containing an isolated electron or muon, missing transverse energy, and two, three or four jets from 2.3 fb{sup -1} of p{bar p} collisions at the Fermilab Tevatron Collider. One or two of the jets are identified as containing a b hadron. We combine three multivariate techniques optimized for the t-channel process to measure the t- and s-channel cross sections simultaneously. We measure cross sections of 3.14{sub -0.80}{sup +0.94} pb for the t-channel and 1.05 {+-} 0.81 pb for the s-channel. The measured t-channel result is found to have a significance of 4.8 standard deviations and is consistent with the standard model prediction.
Date:
July 1, 2009
Creator:
Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Abolins, Maris A.; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of trilinear gauge boson couplings from at {\boldmath$\sqrt{s}=1.96$} TeV
We present a direct measurement of trilinear gauge boson couplings at gammaWW and ZWW vertices in WW and WZ events produced in p{bar p} collisions at {radical}s = 1.96 TeV. We consider events with one electron or muon, missing transverse energy, and at least two jets. The data were collected using the D0 detector and correspond to 1.1 fb{sup -1} of integrated luminosity. Considering two different relations between the couplings at the gammaWW and ZWW vertices, we measure these couplings at 68% C.L. to be kappa{sub gamma} = 1.07{sub -0.29}{sup +0.26}, lambda = 0.00{sub -0.06}{sup +0.06}, and g{sub 1}{sup Z} = 1.04{sup -0.09}{sup +0.09} in a scenario respecting SU(2){sub L}[direct-product]U(1){sub Y} gauge symmetry and kappa = 1.04{sub -0.11}{sup +0.11} and lambda=0.00{sub -0.06}{sup +0.06} in an 'equal couplings' scenario.
Date:
July 1, 2009
Creator:
Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Abolins, Maris A.; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd et al.
Object Type:
Article
System:
The UNT Digital Library
Measurement of Z/gamma*+jet+X angular distributions in p anti-p collisions at s**(1/2) = 1.96.TeV
We present the first measurements at a hadron collider of differential cross sections for Z/{gamma}* + jet + X production in {Delta}{phi}(Z, jet), |{Delta}y(Z, jet)| and |y{sub boost}(Z + jet)|. Vector boson production in association with jets is an excellent probe of QCD and constitutes the main background to many small cross section processes, such as associated Higgs production. These measurements are crucial tests of the predictions of perturbative QCD and current event generators, which have varied success in describing the data. Using these measurements as inputs in tuning event generators will increase the experimental sensitivity to rare signals.
Date:
July 1, 2009
Creator:
Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Abolins, Maris A.; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd et al.
Object Type:
Article
System:
The UNT Digital Library
A Novel method for modeling the recoil in W boson events at hadron collider
We present a new method for modeling the hadronic recoil in W {yields} {ell}{nu} events produced at hadron colliders. The recoil is chosen from a library of recoils in Z {yields} {ell}{ell} data events and overlaid on a simulated W {yields} {ell}{nu} event. Implementation of this method requires that the data recoil library describe the properties of the measured recoil as a function of the true, rather than the measured, transverse momentum of the boson. We address this issue using a multidimensional Bayesian unfolding technique. We estimate the statistical and systematic uncertainties from this method for the W boson mass and width measurements assuming 1 fb{sup -1} of data from the Fermilab Tevatron. The uncertainties are found to be small and comparable to those of a more traditional parameterized recoil model. For the high precision measurements that will be possible with data from Run II of the Fermilab Tevatron and from the CERN LHC, the method presented in this paper may be advantageous, since it does not require an understanding of the measured recoil from first principles.
Date:
July 1, 2009
Creator:
Abazov, Victor Mukhamedovich; Abbott, Braden Keim; Abolins, Maris A.; Acharya, Bannanje Sripath; Adams, Mark Raymond; Adams, Todd et al.
Object Type:
Article
System:
The UNT Digital Library
NOVEL GAS CLEANING/CONDITIONING FOR INTEGRATED GASIFICATION COMBINED CYCLE
The objective of this program is to develop and evaluate novel sorbents for the Siemens Westinghouse Power Company's (SWPC's) ''Ultra-Clean Gas Cleaning Process'' for reducing to near-zero levels the sulfur- and chlorine-containing gas emissions and fine particulate matter (PM2.5) caused by fuel bound constituents found in carbonaceous materials, which are processed in Integrated Gasification Combined Cycle (IGCC) technologies.
Date:
July 1, 2001
Creator:
Abbasian, Javad
Object Type:
Report
System:
The UNT Digital Library
Basin amplification of seismic waves in the city of Pahrump, Nevada.
Sedimentary basins can increase the magnitude and extend the duration of seismic shaking. This potential for seismic amplification is investigated for Pahrump Valley, Nevada-California. The Pahrump Valley is located approximately 50 km northwest of Las Vegas and 75 km south of the Nevada Test Site. Gravity data suggest that the city of Pahrump sits atop a narrow, approximately 5 km deep sub-basin within the valley. The seismic amplification, or ''site effect'', was investigated using a combination of in situ velocity modeling and comparison of the waveforms and spectra of weak ground motion recorded in the city of Pahrump, Nevada, and those recorded in the nearby mountains. Resulting spectral ratios indicate seismic amplification factors of 3-6 over the deepest portion of Pahrump Valley. This amplification predominantly occurs at 2-2.5 Hz. Amplification over the deep sub-basin is lower than amplification at the sub-basin edge, location of the John Blume and Associates PAHA seismic station, which recorded many underground nuclear tests at the Nevada Test Site. A comprehensive analysis of basin amplification for the city of Pahrump should include 3-D basin modeling, due to the extreme basement topography of the Pahrump Valley.
Date:
July 1, 2005
Creator:
Abbott, Robert E.
Object Type:
Report
System:
The UNT Digital Library
Experimental Investigation of the Root Cause Mechanism and Effectiveness of Mitigating Actions for Axial Offset Anomaly in Pressurized Water Reactors
Axial offset anomaly (AOA) in pressurized water reactors refers to the presence of a significantly larger measured negative axial offset deviation than predicted by core design calculations. The neutron flux depression in the upper half of high-power rods experiencing significant subcooled boiling is believed to be caused by the concentration of boron species within the crud layer formed on the cladding surface. Recent investigations of the root-cause mechanism for AOA [1,2] suggest that boron build-up on the fuel is caused by precipitation of lithium metaborate (LiBO2) within the crud in regions of subcooled boiling. Indirect evidence in support of this hypothesis was inferred from operating experience at Callaway, where lithium return and hide-out were, respectively, observed following power reductions and power increases when AOA was present. However, direct evidence of lithium metaborate precipitation within the crud has, heretofore, not been shown because of its retrograde solubility. To this end, this investigation has been undertaken in order to directly verify or refute the proposed root-cause mechanism of AOA, and examine the effectiveness of possible mitigating actions to limit its impact in high power PWR cores.
Date:
July 2, 2005
Creator:
Abdel-Khalik, Said
Object Type:
Report
System:
The UNT Digital Library
Simulation of the Future LSST Data Pipelines
In this paper we describe our approach to build a pipeline simulator for the future Large-scale Synoptic Survey Telescope (LSST). The simulated pipeline will be used to research and evaluate software architectures that are efficient and flexible. It will also be used to define the real-time software and hardware requirements needed to support the anticipated LSST data rates. The LSST data pipeline requirements are still being defined, however, previous surveys can provide a good source for data requirements. Our approach is to use the SuperMacho data pipeline as a prototyping tool to identify a framework for building Modular Data-Centric Pipeline (MDCP) architectures. The prototyping is done in a hierarchical fashion to help capture and define the general data attributes (schema) first. We then model other necessary components based on science and performance requirements. We use identified schemas or data attributes as a way to define a data model for LSST.
Date:
July 26, 2004
Creator:
Abdulla, Ghaleb M.
Object Type:
Article
System:
The UNT Digital Library
Evaluate the Life History of Native Salmonids in the Malheur Subbasin, Fiscal Year 2008 Annual Report.
This report has the following chapters: (1) Synopsis of 2000-2008 Stream Temperature Monitoring with Implications for Bull Trout Recovery in the Upper Malheur Logan Valley Wildlife Mitigation Property, 2008; (2) Bull Trout Spawning Survey Report, 2008; (3) 2008 Efforts to Trap and Haul Entrained Bull Trout Salvelinus confluentus over Agency Valley Dam on the North Fork Malheur River, Oregon; (4) Distribution and Abundance of Redband Trout Oncorhynchus mykiss in the Malheur River Basin, 2008; and (5) Spatial Patterns of Hybridization between Bull Trout, Salvelinus confluentus, and Brook Trout, Salvelinus fontinalis in an Oregon Stream Network.
Date:
July 15, 2009
Creator:
Abel, Chad; Brown, Daniel & Schwabe, Lawrence
Object Type:
Report
System:
The UNT Digital Library
Strange Particle Production in $p+p$ Collisions at $\sqrt{s}$= 200GeV
We present strange particle spectra and yields measured atmid-rapidity in sqrt text s=200 GeV proton-proton (p+p) collisions atRHIC. We find that the previously observed universal transverse mass(mathrm mT \equiv\sqrt mathrm p_T 2+\mathrm m2) scaling of hadronproduction in p+p collisions seems to break down at higher \mt and thatthere is a difference in the shape of the \mt spectrum between baryonsand mesons. We observe mid-rapidity anti-baryon to baryon ratios nearunity for Lambda and Xi baryons and no dependence of the ratio ontransverse momentum, indicating that our data do not yet reach thequark-jet dominated region. We show the dependence of the mean transversemomentum (\mpt) on measured charged particle multiplicity and on particlemass and infer that these trends are consistent with gluon-jet dominatedparticle production. The data are compared to previous measurements fromCERN-SPS, ISR and FNAL experiments and to Leading Order (LO) and Next toLeading order (NLO) string fragmentation model predictions. We infer fromthese comparisons that the spectral shapes and particle yields from $p+p$collisions at RHIC energies have large contributions from gluon jetsrather than quark jets.
Date:
July 31, 2006
Creator:
Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type:
Article
System:
The UNT Digital Library
Transverse momentum and centrality dependence of high-ptnon-photonic electron suppression in Au+Au collisions at $\sqrt{s_{NN}}$= 200 GeV
The STAR collaboration at RHIC reports measurements of theinclusive yield of non-photonic electrons, which arise dominantly fromsemi-leptonic decays of heavy flavor mesons, over a broad range oftransverse momenta (1.2<pt<10 gevc) in pp, dAu, and AuAucollisions at sqrt sNN = 200 GeV. The non-photonic electron yieldexhibits unexpectedly large suppression in central AuAu collisions athigh pt, suggesting substantial heavy quark energy loss at RHIC. Thecentrality and \pt dependences of the suppression provide constraints ontheoretical models of suppression.
Date:
July 11, 2006
Creator:
Abelev, B. I.; Adams, J.; Aggarwal, M. M.; Ahammed, Z.; Amonett, J.; Anderson, B. D. et al.
Object Type:
Article
System:
The UNT Digital Library