Search for neutral Higgs bosons decaying to tau pairs in p anti-p collisions at s**(1/2) = 1.96-TeV (open access)

Search for neutral Higgs bosons decaying to tau pairs in p anti-p collisions at s**(1/2) = 1.96-TeV

A search for the production of neutral Higgs bosons {Phi} decaying into {tau}{sup +}{tau}{sup -} final states in p{bar p} collisions at a center-of-mass energy of 1.96 TeV is presented. The data, corresponding to an integrated luminosity of approximately 325 pb{sup -1}, were collected by the D0 experiment at the Fermilab Tevatron Collider. Since no excess compared to the expectation from standard model processes is found, limits on the production cross section times branching ratio are set. The results are combined with those obtained from the D0 search for {Phi}b({bar b}) {yields} b{bar b}b({bar b}) and are interpreted in the minimal supersymmetric standard model.
Date: May 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Search for particles decaying into a Z boson and a photon in p anti-p collisions at s**(1/2) = 1.96-TeV (open access)

Search for particles decaying into a Z boson and a photon in p anti-p collisions at s**(1/2) = 1.96-TeV

The authors present the results of the first search for a new particle X produced in p{bar p} collisions at {radical}s = 1.96 TeV and subsequently decaying to Z{gamma}. The search uses 0.3 fb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron Collider. They set limits on the production cross section times the branching fraction {sigma}(p{bar p} {yields} X) x B(X {yields} Z{gamma}) that range from 0.4-3.5 pb at the 95% C.L. for X with invariant masses between 100 and 1000 GeV/c{sup 2} over a wide range of X decay widths.
Date: May 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Search for R-parity violating supersymmetry via the LL anti-E couplings lambda(121), lambda(122) or lambda(133) in p anti-p collisions at s**(1/2) = 1.96-TeV (open access)

Search for R-parity violating supersymmetry via the LL anti-E couplings lambda(121), lambda(122) or lambda(133) in p anti-p collisions at s**(1/2) = 1.96-TeV

A search for gaugino pair production with a trilepton signature in the framework of R-parity violating supersymmetry via the couplings {lambda}{sub 121}, {lambda}{sub 122}, or {lambda}{sub 133} is presented. The data, corresponding to an integrated luminosity of L {approx} 360 pb{sup -1}, were collected from April 2002 to August 2004 with the D0 detector at the Fermilab Tevatron Collider, at a center-of-mass energy of {radical}s = 1.96 TeV. This analysis considers final states with three charged leptons with the flavor combinations ee{ell}, {mu}{mu}{ell}, and ee{tau} ({ell} = e or {mu}). No evidence for supersymmetry is found and limits at the 95% confidence level are set on the gaugino pair production cross section and lower bounds on the masses of the lightest neutralino and chargino are derived in two supersymmetric models.
Date: May 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Search for resonant second generation slepton production at the Tevatron (open access)

Search for resonant second generation slepton production at the Tevatron

The authors present a search for supersymmetry in the R-parity violating resonant production and decay of smuons and muon-sneutrinos in the channels {tilde {mu}} {yields} {tilde {chi}}{sub 1}{sup 0} {mu}, {tilde {mu}} {yields} {tilde {chi}}{sub 2,3,4}{sup 0} {mu}, and {tilde {nu}}{sub {mu}} {yields} {tilde {chi}}{sub 1,2}{sup {+-}} {mu}. They analyzed 0.38 fb{sup -1} of integrated luminosity collected between April 2002 and August 2004 with the D0 detector at the Fermilab Tevatron Collider. The observed number of events is in agreement with the standard model expectation, and we calculate 95% C.L. limits on the slepton production cross section times branching fraction to gaugino plus muon, as a function of slepton and gaugino masses. In the framework of minimal supergravity, we set limits on the coupling parameter {lambda}'{sub 211}, extending significantly previous results obtained in Run I of the Tevatron and at the CERN LEP collider.
Date: May 1, 2006
Creator: Abazov, V. M.; Abbott, B.; Abolins, M.; Acharya, B. S.; Adams, M.; Adams, T. et al.
System: The UNT Digital Library
Measurement of the b jet cross-section in events with a Z boson in p anti-p collisions at s**(1/2) = 1.96-TeV (open access)

Measurement of the b jet cross-section in events with a Z boson in p anti-p collisions at s**(1/2) = 1.96-TeV

None
Date: May 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M. G. et al.
System: The UNT Digital Library
Measurement of the ratio of branching fractions B(D0 ---> K+ pi-) / B(D0 ---> K- pi+) using the CDF II Detector (open access)

Measurement of the ratio of branching fractions B(D0 ---> K+ pi-) / B(D0 ---> K- pi+) using the CDF II Detector

The authors present a measurement of R{sub B}, the ratio of the branching fraction for the rare decay D{sup 0} {yields} K{sup +}{pi}{sup -} to that for the Cabibbo-favored decay D{sup 0} {yields} K{sup -}{pi}{sup +}. Charge conjugate decays are implicitly included. A signal of 2005 {+-} 104 events for the decay D{sup 0} {yields} K{sup +}{pi}{sup -} is obtained using the CDF II detector at the Fermilab Tevatron collider. The data set corresponds to an integrated luminosity of 0.35 fb{sup -1} produced in {bar p}p collisions at {radical}s = 1.96 TeV. Assuming no mixing, they find R{sub B} = [4.05 {+-} 0.21(stat) {+-} 0.11(syst)] x 10{sup -3}. This measurement is consistent with the world average, and comparable in accuracy with the best measurements from other experiments.
Date: May 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
System: The UNT Digital Library
Search for a neutral Higgs boson decaying to a W boson pair in p antip collisions at s**(1/2) = 1.96-TeV (open access)

Search for a neutral Higgs boson decaying to a W boson pair in p antip collisions at s**(1/2) = 1.96-TeV

The authors present the results of a search for standard model Higgs boson production with decay to WW*, identified through the leptonic final states e{sup +}e{sup -} {bar {nu}}{nu}, e{sup {+-}}{mu}{sup {-+}} {bar {nu}}{nu} and {mu}{sup +} {mu}{sup -} {bar {nu}}{nu}. This search uses 360 pb{sup -1} of data collected from p{bar p} collisions at {radical}s = 1.96 TeV by the upgraded Collider Detector at Fermilab (CDF II). They observe no signal excess and set 95% confidence level upper limits on the production cross section times branching ratio for the Higgs boson to WW* or any new scalar particle with similar decay products. These upper limits range from 5.5 to 3.2 pb for Higgs boson masses between 120 and 200 GeV/c{sup 2}.
Date: May 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
System: The UNT Digital Library
Search for new physics in lepton + photon + X events with 305 pb**-1 of p anti-p collisions at s**(1/2) = 1.96-TeV (open access)

Search for new physics in lepton + photon + X events with 305 pb**-1 of p anti-p collisions at s**(1/2) = 1.96-TeV

The authors present results of a search for anomalous production of events containing a charged lepton ({ell}, either e or {mu}) and a photon ({gamma}), both with high transverse momentum, accompanied by additional signatures, X, including missing transverse energy (E{sub T}) and additional leptons and photons. We use the same kinematic selection criteria as in a previous CDF search, but with a substantially larger data set, 305 pb{sup -1}, a p{bar p} collision energy of 1.96 TeV, and the upgraded CDF II detector. We find 42 {ell}{gamma}E{sub T} events versus a standard model expectation of 37.3 {+-} 5.4 events. The level of excess observed in Run I, 16 events with an expectation of 7.6 {+-} 0.7 events (corresponding to a 2.7{sigma} effect), is not supported by the new data. In the signature of {ell}{ell}{gamma} + X we observe 31 events versus an expectation of 23.0 {+-} 2.7 events. In this sample we find no events with an extra photon or E{sub T} and so find no events like the one ee{gamma}{gamma}E{sub T} event observed in Run I.
Date: May 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
System: The UNT Digital Library
Top quark mass measurement from dilepton events at CDF II with the matrix-element method (open access)

Top quark mass measurement from dilepton events at CDF II with the matrix-element method

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 {radical}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} {yields} t{bar t} {yields} b{ell}{nu}{sub {ell}}{bar b}{ell}{prime} {nu}{sub {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 luminosity of 340 pb{sup -1}, we observe 33 candidate events and measure M{sub top} = 165.2 {+-} 6.1(stat.) {+-} 3.4(syst.) GeV/c{sup 2}. This measurement represents the first application of this method to events with two charged leptons and is the most precise single measurement of the top quark mass in this channel.
Date: May 1, 2006
Creator: Abulencia, A.; Acosta, D.; Adelman, Jahred A.; Affolder, T.; Akimoto, T.; Albrow, M.G. et al.
System: The UNT Digital Library
An Integrated Hydrologic Bayesian Multi-Model Combination Framework: Confronting Input, parameter and model structural uncertainty in Hydrologic Prediction (open access)

An Integrated Hydrologic Bayesian Multi-Model Combination Framework: Confronting Input, parameter and model structural uncertainty in Hydrologic Prediction

This paper presents a new technique--Integrated Bayesian Uncertainty Estimator (IBUNE) to account for the major uncertainties of hydrologic rainfall-runoff predictions explicitly. The uncertainties from the input (forcing) data--mainly the precipitation observations and from the model parameters are reduced through a Monte Carlo Markov Chain (MCMC) scheme named Shuffled Complex Evolution Metropolis (SCEM) algorithm which has been extended to include a precipitation error model. Afterwards, the Bayesian Model Averaging (BMA) scheme is employed to further improve the prediction skill and uncertainty estimation using multiple model output. A series of case studies using three rainfall-runoff models to predict the streamflow in the Leaf River basin, Mississippi are used to examine the necessity and usefulness of this technique. The results suggests that ignoring either input forcings error or model structural uncertainty will lead to unrealistic model simulations and their associated uncertainty bounds which does not consistently capture and represent the real-world behavior of the watershed.
Date: May 5, 2006
Creator: Ajami, N. K.; Duan, Q. & Sorooshian, S.
System: The UNT Digital Library
Multi-Model Combination Techniques for Hydrological Forecasting: Application to Distributed Model Intercomparison Project Results (open access)

Multi-Model Combination Techniques for Hydrological Forecasting: Application to Distributed Model Intercomparison Project Results

This paper examines several multi-model combination techniques: the Simple Multimodel Average (SMA), the Multi-Model Super Ensemble (MMSE), Modified Multi-Model Super Ensemble (M3SE) and the Weighted Average Method (WAM). These model combination techniques were evaluated using the results from the Distributed Model Intercomparison Project (DMIP), an international project sponsored by the National Weather Service (NWS) Office of Hydrologic Development (OHD). All of the multi-model combination results were obtained using uncalibrated DMIP model outputs and were compared against the best uncalibrated as well as the best calibrated individual model results. The purpose of this study is to understand how different combination techniques affect the skill levels of the multi-model predictions. This study revealed that the multi-model predictions obtained from uncalibrated single model predictions are generally better than any single member model predictions, even the best calibrated single model predictions. Furthermore, more sophisticated multi-model combination techniques that incorporated bias correction steps work better than simple multi-model average predictions or multi-model predictions without bias correction.
Date: May 8, 2006
Creator: Ajami, N.; Duan, Q.; Gao, X. & Sorooshian, S.
System: The UNT Digital Library
Determination of linear optics functions from TBT data (open access)

Determination of linear optics functions from TBT data

A method for evaluation of coupled optics functions, detection of strong perturbing elements, determination of BPM calibration errors and tilts using turn-by-turn (TBT) data is presented as well as the new version of the Hamiltonian perturbation theory of betatron oscillations the method is based upon. An example of application of the considered method to the Tevatron is given.
Date: May 1, 2006
Creator: Alexahin, Y. & Gianfelice-Wendt, E.
System: The UNT Digital Library
Electronic Properties of LiFePO4 and Li doped LiFePO4 (open access)

Electronic Properties of LiFePO4 and Li doped LiFePO4

LiFePO{sub 4} has several potential advantages in comparison to the transition metal oxide cathode materials used in commercial lithium-ion batteries. However, its low intrinsic electronic conductivity ({approx} 10{sup -9} S/cm) is problematic. We report here a study by soft x-ray absorption/emission spectroscopy of the electronic properties of undoped LiFePO{sub 4} and Li-doped LiFePO{sub 4} in which Li{sup +} ions are substituted for Fe{sup 2+} ions in an attempt to increase the intrinsic electronic conductivity. The conductivities of the Li{sub 1+x}Fe{sub 1-x}PO{sub 4} samples were, however, essentially unchanged from that of the undoped LiFePO{sub 4}. Nonetheless, evidence for changing the electronic properties of LiFePO{sub 4} by doping with excess Li+ was observed by the XAS/XES spectroscopy. New pre-edge features the O-1s XAS spectrum of Li{sub 1.05}Fe{sub 0.95}PO4 is a direct indication that the charge compensation for substitution of Fe{sup 2+} by Li{sup +} resides in the unoccupied O-2p orbitals. A charge transfer (CT) excitation was also observed in the doped material implying that the unoccupied O-2p orbitals created by doping are strongly hybridized with unoccupied Fe-3d orbitals of neighboring sites. However, the strong covalent bonding within the (PO{sub 4}){sup 3-} anions and the large separation of the Fe cations means that …
Date: May 31, 2006
Creator: Allen, J.L.; Zhuang, G.V.; Ross, P.N.; Guo, J.-H. & Jow, T.R.
System: The UNT Digital Library
Geant4 Developments And Applications (open access)

Geant4 Developments And Applications

None
Date: May 19, 2006
Creator: Allison, J.; Amako, K.; Apostolakis, J.; Araujo, H.; Dubois, P.A.; Asai, M. et al.
System: The UNT Digital Library
Probing low-x QCD with cosmic neutrinos at the Pierre Auger Observatory (open access)

Probing low-x QCD with cosmic neutrinos at the Pierre Auger Observatory

The sources of the observed ultra-high energy cosmic rays must also generate ultra-high energy neutrinos. Deep inelastic scattering of these neutrinos with nucleons on Earth probe center-of-mass energies {radical}s {approx} 100 TeV, well beyond those attainable at terrestrial colliders. By comparing the rates for two classes of observable events, any departure from the benchmark (unscreened perturbative QCD) neutrino-nucleon cross-section can be constrained. Using the projected sensitivity of the Pierre Auger Observatory to quasi-horizontal showers and Earth-skimming tau neutrinos, we show that a ''Super-Auger'' detector can thus provide an unique probe of strong interaction dynamics.
Date: May 1, 2006
Creator: Anchordoqui, Luis A.; Cooper-Sarkar, Amanda M.; Hooper, Dan & Sarkar, Subir
System: The UNT Digital Library
Understanding of decay length resolution and its application to bs mixing (open access)

Understanding of decay length resolution and its application to bs mixing

None
Date: May 1, 2006
Creator: Anzelc, Meghan
System: The UNT Digital Library
Zero Energy Windows (open access)

Zero Energy Windows

Windows in the U.S. consume 30 percent of building heating and cooling energy, representing an annual impact of 4.1 quadrillion BTU (quads) of primary energy. Windows have an even larger impact on peak energy demand and on occupant comfort. An additional 1 quad of lighting energy could be saved if buildings employed effective daylighting strategies. The ENERGY STAR{reg_sign} program has made standard windows significantly more efficient. However, even if all windows in the stock were replaced with today's efficient products, window energy consumption would still be approximately 2 quads. However, windows can be ''net energy gainers'' or ''zero-energy'' products. Highly insulating products in heating applications can admit more useful solar gain than the conductive energy lost through them. Dynamic glazings can modulate solar gains to minimize cooling energy needs and, in commercial buildings, allow daylighting to offset lighting requirements. The needed solutions vary with building type and climate. Developing this next generation of zero-energy windows will provide products for both existing buildings undergoing window replacements and products which are expected to be contributors to zero-energy buildings. This paper defines the requirements for zero-energy windows. The technical potentials in terms of national energy savings and the research and development (R&D) status …
Date: May 17, 2006
Creator: Arasteh, Dariush; Selkowitz, Steve; Apte, Josh & LaFrance, Marc
System: The UNT Digital Library
Practical Considerations for High Spatial and Temporal Resolution Dynamic Transmission Electron Microscopy (open access)

Practical Considerations for High Spatial and Temporal Resolution Dynamic Transmission Electron Microscopy

Although recent years have seen significant advances in the spatial resolution possible in the transmission electron microscope (TEM), the temporal resolution of most microscopes is limited to video rate at best. This lack of temporal resolution means that our understanding of dynamic processes in materials is extremely limited. High temporal resolution in the TEM can be achieved, however, by replacing the normal thermionic or field emission source with a photoemission source. In this case the temporal resolution is limited only by the ability to create a short pulse of photoexcited electrons in the source, and this can be as short as a few femtoseconds. The operation of the photo-emission source and the control of the subsequent pulse of electrons (containing as many as 5 x 10{sup 7} electrons) create significant challenges for a standard microscope column that is designed to operate with a single electron in the column at any one time. In this paper, the generation and control of electron pulses in the TEM to obtain a temporal resolution <10{sup -6} s will be described and the effect of the pulse duration and current density on the spatial resolution of the instrument will be examined. The potential of these …
Date: May 1, 2006
Creator: Armstrong, Michael; Boyden, Ken; Browning, Nigel D.; Campbell, Geoffrey H.; Colvin, Jeffrey D.; DeHope, Bill et al.
System: The UNT Digital Library
Meeting the Renewable Energy Challenge: What Will it Take to Reach Solar PV's Ultimate Potential (open access)

Meeting the Renewable Energy Challenge: What Will it Take to Reach Solar PV's Ultimate Potential

Presented at the 2006 IEEE 4th World Conference on Photovoltaic Energy Conversion on May 8, 2006 by Dr. Dan E. Arvizu, Director, National Renewable Energy Laboratory (NREL).
Date: May 1, 2006
Creator: Arvizu, D.
System: The UNT Digital Library
NNLL QCD Contribution of the Electromagentic Dipole Operator to \bar B --> X_s gamma (open access)

NNLL QCD Contribution of the Electromagentic Dipole Operator to \bar B --> X_s gamma

We present an independent calculation of that part of the O({alpha}{sub s}{sup 2}) contribution to dipole operator {Omicron}{sub 7}. Using a different method, we find complete agreement mass ambiguity appearing at NLL accuracy. the complete NNLL prediction of {Lambda}({bar B} {yields} X{sub s}{gamma}) which will resolve the charm quark the decay width {Lambda}({bar B} {yields} X{sub s}{gamma}) which arises from the self-interference term of the electromagnetic with a previous calculation. This NNLL contribution is an important ingredient for
Date: May 16, 2006
Creator: Asatrian, H.M.; Hovhannisyan, A.; Poghosyan, V.; Inst., /Yerevan Phys.; Ewerth, T.; Greub, C. et al.
System: The UNT Digital Library
Searches for Astrophysical and Cosmological Axions (open access)

Searches for Astrophysical and Cosmological Axions

The axion remains, after nearly 30 years, the most compelling and elegant solution to the strong-CP problem, i.e. why this symmetry is protected in QCD in spite of CP violation elsewhere. The axion is expected to be extremely light, and possess extraordinarily feeble couplings to matter and radiation. Because of its small couplings, the axion has defied experimental confirmation and is unlikely to be discovered in conventional laboratory experiments (i.e. production-detection). Nevertheless, a sufficiently light axion would have been produced abundantly in the Big Bang and is an excellent candidate for the dark matter of the Universe. Through the axion's two-photon coupling, implying axion-photon mixing in an external electromagnetic field, galactic halo axions may be feasibly detected by their resonant conversion to RF photons in a microwave cavity permeated by magnetic field with current technology. Over the past decade experiments have already set interesting limits in mass and coupling; upgrades in progress to photon detection schemes at or below the standard quantum limit will soon enable definitive searches. Similarly, axions produced in the solar burning core might be detectable by their conversion to x-rays in a magnetic helioscope. Indeed current published limits already equal the best bounds on axion-photon coupling …
Date: May 3, 2006
Creator: Asztalos, S J; Rosenberg, L J; van Bibber, K; Sikivie, P & Zioutas, K
System: The UNT Digital Library
MODIFIED BOROHYDRIDES FOR REVERSIBLE HYDROGEN STORAGE (open access)

MODIFIED BOROHYDRIDES FOR REVERSIBLE HYDROGEN STORAGE

This paper reports the results in the effort to destabilize lithium borohydride for reversible hydrogen storage. A number of metals, metal hydrides, metal chlorides and complex hydrides were selected and evaluated as the destabilization agents for reducing dehydriding temperature and generating dehydriding-rehydriding reversibility. It is found that some additives are effective. The Raman spectroscopic analysis shows the change of B-H binding nature.
Date: May 10, 2006
Creator: Au, Ming
System: The UNT Digital Library
Measurement of th eta and etaprime Transition Form Factors at q^2 = 112 GeV^2 (open access)

Measurement of th eta and etaprime Transition Form Factors at q^2 = 112 GeV^2

The authors report a study of the processes e{sup +}e{sup -} {yields} {eta}{gamma} and e{sup +}e{sup -} {yields} {eta}'{gamma} at a center-of-mass energy of 10.58 GeV, using a 232 fb{sup -1} data sample collected with the BABAR detector at the PEP-II collider at SLAC.
Date: May 16, 2006
Creator: Aubert, B.
System: The UNT Digital Library
Study of B -> D^(*)D_s(J)^(*) Decays andMeasurement of D_s^- and D_s(J)(2460)- Branching Fractions (open access)

Study of B -> D^(*)D_s(J)^(*) Decays andMeasurement of D_s^- and D_s(J)(2460)- Branching Fractions

We present branching fraction measurements of twelve B meson decays of the form B {yields} D{sup (*)} D{sub s(J)}{sup (*)}. The results are based on {Upsilon}(4S) decays in B{bar B} pairs. One of the B mesons is fully reconstructed and the other decays to two charm mesons, of which one is reconstructed, and the mass and momentum of the other is inferred by kinematics. Combining these results with previous exclusive branching fraction measurements, we determine {Beta}(D{sub s}{sup -} {yields} {phi}{pi}{sup -}) = (4.62 {+-} 0.36{sub stat.} {+-} 0.51{sub syst.})%, {Beta}(D{sub sJ}(2460){sup -} {yields} D*{sub s}{sup -} {pi}{sup 0}) = (56 {+-} 13{sub stat.} {+-} 9{sub syst.})% and {Beta}(D{sub sJ}(2460){sup -} {yields} D{sub s}{sup -}{gamma}) = (16 {+-} 4{sub stat.} {+-} 3{sub syst.})%.
Date: May 16, 2006
Creator: Aubert, B.; Barate, R.; Bona, M.; Boutigny, D.; Couderc, F.; Karyotakis, Y. et al.
System: The UNT Digital Library