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The Sharp Lepton Quandary: Reasonable cautions

Description: Surprisingly, the new APEX experiment designed to measure a definitive invariant mass distribution of the sharp pairs previously reported in similar heavy ion studies reports null results. Although it asserts no direct conflict with any data reported by EPOS/I, the APEX report nevertheless seems to have encouraged the view that the earlier (EPOS/I) observations were erroneous, and by extrapolation, that the whole (e{sup +}e{sup {minus}}) Puzzle data set can be dismissed as an unfortunate set of physically meaningless statistical fluctuations. We wish here to argue that such sweeping judgments should be postponed, on the grounds that (1) the published APEX analysis of their data is self-inconsistent, and can therefore sustain no valid inference about the EPOS/I data; (2) the data which supports the occurrence of sharp (e{sup +}e{sup {minus}}) pairs is much more extensive than the EPOS/I data, so that the APEX surprise must be considered as one episode in a much longer struggle finally to settle the question of whether these weak signals are significant or not; (3) a qualitative phenomenology exists which can organize the whole range of data of the Sharp Lepton Problem, and which suggests that (4) certain low energy (and low cost) experiments ought to be explored for their creation of sharp pairs; as follows: the study of pairs emitted following scattering of few MeV electron and positron beams from neutral U and Th atoms, and the study of pairs emitted following the resonant absorption of photons of 1.5 to 2.0 MeV on U and Th atoms. We first present a brief data-oriented history of the Sharp Lepton Problem, to show that no single unexpected null result can provide an adequate basis for rejecting the great range and quantity of data which evidences the occurrence of sharp pairs. We then consider the Quadronium Composite Particle ...
Date: February 1, 1996
Creator: Griffin, J.J.
Partner: UNT Libraries Government Documents Department

Studies of Nonlinear QED in Collisions of 46.6 Electrons with Intense LaserPulses

Description: We report on measurements of quantum electrodynamic processes in an intense electromagnetic wave, where nonlinear effects (both multiphoton and vacuum polarization) are prominent. Nonlinear Compton scattering and electron-positron pair production have been observed in collisions of 46.6 GeV and 49.1 GeV electrons of the Final Focus Test Beam at SLAC with terawatt pulses of 1053 nm and 527 nm wavelengths from a Nd:glass laser. Peak laser intensities of approximately 0.5 x 10{sup 18} W/cm{sup 2} have been achieved, corresponding to a value of approximately 0.4 for the parameter {eta} = eE{sub rms}/m{omega}{sub 0}c, and to a value of approximately 0.25 for the parameter {Upsilon}{sub e} = E{sub rms}/E{sub crit} = eE{sub rms}{h_bar}/m{sup 2}c{sup 3}, where E{sub rms} is the rms electric field strength of the laser in the electron rest frame. We present data on the scattered electron spectra arising from nonlinear Compton scattering with up to four photons absorbed from the field. A convolved spectrum of the forward high energy photons is also given. The observed positron production rate depends on the fifth power of the laser intensity, as expected for a process where five photons are absorbed from the field. The positrons are interpreted as arising from the collision of a high-energy Compton scattered photon with the laser beam. The results are found to be in agreement with theoretical predictions.
Date: February 16, 1999
Creator: McDonald, Kirk T.
Partner: UNT Libraries Government Documents Department


Description: The Paducah Gaseous Diffusion Plant (PGDP), owned by the Department of Energy (DOE), has been enriching uranium since the early 1950s. The enrichment process involves electrical and mechanical components that require periodic cleaning. The primary cleaning agent was trichloroethene (TCE) until the late 1980s. Historical documentation indicates that a mixture of TCE and dry ice were used at PGDP for testing the integrity of steel cylinders, which stored depleted uranium. TCE and dry ice were contained in a below-ground pit and used during the integrity testing. TCE seeped from the pit and contaminated the surrounding soil. The Lasagna{trademark} technology was identified in the Record of Decision (ROD) as the selected alternative for remediation of the cylinder testing site. A public-private consortium formed in 1992 (including DOE, the U.S. Environmental Protection Agency, and the Kentucky Department for Environmental Protection, Monsanto, DuPont, and General Electric) developed the Lasagna{trademark} technology. This innovative technology employs electrokinetics to remediate soil contaminated with organics and is especially suited to sites with low permeability soils. This technology uses direct current to move water through the soil faster and more uniformly than hydraulic methods. Electrokinetics moves contaminants in soil pore water through treatment zones comprised of iron filings, where the contaminants are decomposed to basic chemical compounds such as ethane. After three years of development in the laboratory, the consortium field tested the Lasagna{trademark} process in several phases. CDM installed and operated Phase I, the trial installation and field test of a 150-square-foot area selected for a 120-day run in 1995. Approximately 98 percent of the TCE was removed. CDM then installed and operated the next phase (IIa), a year-long test on a 600-square-foot site. Completed in July 1997, this test removed 75 percent of the total volume of TCE down to a depth of 45 feet. TCE ...
Date: February 27, 2003
Creator: Swift, Barry D. & Tarantino, Joseph J., P. E.
Partner: UNT Libraries Government Documents Department

Stability Issues in Ambient-Temperature Passive Magnetic Bearing Systems

Description: The ambient-temperature passive magnetic bearing system developed at the Lawrence Livermore National Laboratory achieves rotor-dynamic stability by employing special combinations of levitating and stabilizing elements. These elements, energized by permanent magnet material, create the magnetic and electrodynamic forces that are required for the stable levitation of rotating systems, such as energy-storage flywheels. Stability criteria, derived from theory, describe the bearing element parameters, i.e., stiffnesses and damping coefficients, that are required both to assure stable levitation (''Earnshaw-stability''), and stability against whirl-type rotor-dynamic instabilities. The work described in this report concerns experimental measurements and computer simulations that address some critical aspects of this overall stability problem. Experimentally, a test device was built to measure the damping coefficient of dampers that employ eddy currents induced in a metallic disc. Another test device was constructed for the purpose of measuring the displacement-dependent drag coefficient of annular permanent magnet bearing elements. In the theoretical developments a computer code was written for the purpose of simulating the rotor-dynamics of our passive bearing systems. This code is capable of investigating rotor-dynamic stability effects for both small-amplitude transient displacements (i.e., those within the linear regime), and for large-amplitude displacements, where non-linear effects can become dominant. Under the latter conditions a bearing system that is stable for small-amplitude displacements may undergo a rapidly growing rotor-dynamic instability once a critical displacement is exceeded. A new result of the study was to demonstrate that stiffness anisotropy of the bearing elements (which can be designed into our bearing system) is strongly stabilizing, not only in the linear regime, but also in the non-linear regime.
Date: February 17, 2000
Creator: Post, R.F.
Partner: UNT Libraries Government Documents Department

Topics in gauge theories and the unification of elementary particle interactions. [Northeastern Univ. , Boston Massachusetts]

Description: Work done on the following topics is summarized: (1) Coulomb potential in QED on the lattice; (2) Weyl cosmic strings and their consequences; (3) Interference between past and future events in [phi] [yields] K[bar K]; (4) Quantum effects of strong classical electromagnetic fields; (5) Application of computer algebra to calculations in supersymmetry and supergravity; (6) numerical studies of classical scalar [phi][sup 4] field theory and related nonlinear [sigma]-models; (7) Analysis of a cubic model field theory; and, (8) Renormalization group analysis of unified gauge theories.
Date: February 1, 1993
Creator: Srivastava, Y.N. & Vaughn, M.T.
Partner: UNT Libraries Government Documents Department

The search for charged-lepton specific forces and the PEGASYS facility

Description: This paper discusses the electroproduction of lepton pairs as a method of searching for a charged-lepton specific force, and as a general method of searching for deviations from conventional quantum electrodynamics. The use of the PEGASYS facility for these purposes is briefly described. Search possibilities in other energy ranges are noted. 22 refs., 11 figs.
Date: February 1, 1989
Creator: Perl, M.L.
Partner: UNT Libraries Government Documents Department

Atoms in Flight: The Remarkable Connections between Atomic and Hadronic Physics

Description: Atomic physics and hadron physics are both based on Yang Mills gauge theory; in fact, quantum electrodynamics can be regarded as the zero-color limit of quantum chromodynamics. I review a number of areas where the techniques of atomic physics provide important insight into the theory of hadrons in QCD. For example, the Dirac-Coulomb equation, which predicts the spectroscopy and structure of hydrogenic atoms, has an analog in hadron physics in the form of light-front relativistic equations of motion which give a remarkable first approximation to the spectroscopy, dynamics, and structure of light hadrons. The renormalization scale for the running coupling, which is unambiguously set in QED, leads to a method for setting the renormalization scale in QCD. The production of atoms in flight provides a method for computing the formation of hadrons at the amplitude level. Conversely, many techniques which have been developed for hadron physics, such as scaling laws, evolution equations, and light-front quantization have equal utility for atomic physics, especially in the relativistic domain. I also present a new perspective for understanding the contributions to the cosmological constant from QED and QCD.
Date: February 16, 2012
Creator: Brodsky, Stanley J.
Partner: UNT Libraries Government Documents Department

Optical properties of the Ce and La ditelluride charge density wave compounds

Description: The La and Ce di-tellurides LaTe{sub 2} and CeTe{sub 2} are deep in the charge-density-wave (CDW) ground state even at 300 K. We have collected their electrodynamic response over a broad spectral range from the far infrared up to the ultraviolet. We establish the energy scale of the single particle excitation across the CDW gap. Moreover, we find that the CDW collective state gaps a very large portion of the Fermi surface. Similarly to the related rare earth tri-tellurides, we envisage that interactions and Umklapp processes play a role in the onset of the CDW broken symmetry ground state.
Date: February 15, 2010
Creator: Lavagnini, M.; Sacchetti, A.; Degiorgi, L.; Shin, K. Y. & Fisher, I. R.
Partner: UNT Libraries Government Documents Department

Observation of the doubly strange b-Baryon Omega(b)-

Description: This thesis reports the first experimental evidence of the doubly strange b-baryon {Omega}{sub b}{sup -} (ssb) following the decay channel {Omega}{sub b}{sup -} {yields} J/{psi}(1S) {mu}{sup +}{mu}{sup -} {Omega}{sup -} {Lambda} K{sup -} p {pi}{sup -} in p{bar p} collisions at {radical}s = 1.96 Tev. Using approximately 1.3 fb{sup -1} of data collected with the D0 detector at the Fermilab Tevatron Collider, they observe 17.8 {+-} 4.9(stat) {+-} 0.8(syst) {Omega}{sub b}{sup -} signal events at 6.165 {+-} 0.010(stat) {+-} 0.013(syst) GeV/c{sup 2} with a corresponding significance of 5.4 {sigma}, meaning that the probability of the signal coming from a fluctuation in the background is 6.7 x 10{sup -8}. The theoretical model we have to describe what we believe are the building blocks of nature and the interactions between them, is known as Standard Model. The Standard Model is the combination of Electroweak Theory and Quantum Chromodynamics into a single core in the attempt to include all interactions of subatomic particles except those due to gravity in a simple framework. This model has proved highly accurate in predicting certain interactions, but it does not explain all aspects of subatomic particles. For example, it cannot say how many particles there should be or what their masses are. The search goes on for a more complete theory, and in particular an unified field theory describing the strong, weak, and electromagnetic forces. Twelve elementary particles are known in the Standard Model: the Fermions. They have spin -1/2 and obey the Pauli Exclusion Principle. Fermions are divided into six Quarks: up u, down d, charm c, strange s, top t and, bottom b; and six Leptons: electron e, muon {mu}, tau {tau}, electron neutrino {nu}{sub e}, muon neutrino {nu}{sub {mu}} and, tau neutrino {nu}{sub {tau}}. Quarks interact via the strong force because they carry color ...
Date: February 1, 2011
Creator: Hernandez Orduna, de Jesus, Jose
Partner: UNT Libraries Government Documents Department

Electrokinetic coupling in unsaturated porous media

Description: We consider a charged porous material that is saturated bytwo fluid phases that are immiscible and continuous on the scale of arepresentative elementary volume. The wetting phase for the grains iswater and the nonwetting phase is assumed to be an electricallyinsulating viscous fluid. We use a volume-averaging approach to derivethe linear constitutive equations for the electrical current density aswell as the seepage velocities of the wetting and nonwetting phases onthe scale of a representative elementary volume. These macroscopicconstitutive equations are obtained by volume-averaging Ampere's lawtogether with the Nernst Planck equation and the Stokes equations. Thematerial properties entering the macroscopic constitutive equations areexplicitly described as functions of the saturation of the water phase,the electrical formation factor, and parameters that describe thecapillary pressure function, the relative permeability function, and thevariation of electrical conductivity with saturation. New equations arederived for the streaming potential and electro-osmosis couplingcoefficients. A primary drainage and imbibition experiment is simulatednumerically to demonstrate that the relative streaming potential couplingcoefficient depends not only on the water saturation, but also on thematerial properties of the sample, as well as the saturation history. Wealso compare the predicted streaming potential coupling coefficients withexperimental data from four dolomite core samples. Measurements on thesesamples include electrical conductivity, capillary pressure, thestreaming potential coupling coefficient at various level of saturation,and the permeability at saturation of the rock samples. We found verygood agreement between these experimental data and the modelpredictions.
Date: February 27, 2007
Creator: Revil, A.; Linde, N.; Cerepi, A.; Jougnot, D.; Matthai, S. & Finsterle, S.
Partner: UNT Libraries Government Documents Department

Electron Anomalous Magnetic Moment in Basis Light-Front Quantization Approach

Description: We apply the Basis Light-Front Quantization (BLFQ) approach to the Hamiltonian field theory of Quantum Electrodynamics (QED) in free space. We solve for the mass eigenstates corresponding to an electron interacting with a single photon in light-front gauge. Based on the resulting non-perturbative ground state light-front amplitude we evaluate the electron anomalous magnetic moment. The numerical results from extrapolating to the infinite basis limit reproduce the perturbative Schwinger result with relative deviation less than 1.2%. We report significant improvements over previous works including the development of analytic methods for evaluating the vertex matrix elements of QED.
Date: February 17, 2012
Creator: Zhao, Xingbo; U., /Iowa State; Honkanen, Heli; U., /Jyvaskyla; Maris, Pieter; Vary, James P. et al.
Partner: UNT Libraries Government Documents Department

Radiation of Electron in the Field of Plane Light Wave

Description: Results of integration of a Lorentz equation for a relativistic electron moving in the field of running, plane, linear polarized electromagnetic wave are presented in the paper. It is shown that electron velocities in the field of the wave are almost periodic functions of time. For calculations of angular spectrum of electron radiation intensity expansion of the electromagnetic field in a wave zone into generalized Fourier series was used. Expressions for the radiation intensity spectrum are presented in the paper. Derived results are illustrated for electron and laser beam parameters of NSC KIPT X-ray generator NESTOR. It is shown that for low intensity of the interacting electromagnetic wave the results of energy and angular spectrum calculations in the frame of classical electrodynamics completely coincide with calculation results produced using quantum electrodynamics. Simultaneously, derived expressions give possibilities to investigate dependence of energy and angular Compton radiation spectrum on phase of interaction and the interacting wave intensity.
Date: February 24, 2006
Creator: Zelinsky, A.; Drebot, I.V.; Grigorev, Yu.N.; Zvonareva, O.D.; /Kharkov, KIPT; Tatchyn, R. et al.
Partner: UNT Libraries Government Documents Department

Looping through the Lamb Shift

Description: Sometimes in science, a small measurement can have big ramifications. For a team of Livermore scientists, such was the case when they measured a small shift in the spectrum of extremely ionized atoms of uranium. The measurement involves the Lamb shift, a subtle change in the energy of an electron orbiting an atom's nucleus. The precision of the Livermore result was 10 times greater than that of existing measurements, making it the best measurement to date of a complicated correction to the simplest quantum description of how atoms behave. The measurement introduces a new realm in the search for deviations between the theory of quantum electrodynamics (QED), which is an extension of quantum mechanics, and the real world. Such deviations, if discovered, would have far-reaching consequences, indicating that QED is not a fundamental theory of nature.
Date: February 6, 2007
Creator: Hazi, A U
Partner: UNT Libraries Government Documents Department

Search for exclusive Z boson production and observation of high mass p anti-p ---> gamma gamma anti-p ---> pl+ l- anti-p events in p anti-p collisions at s**(1/2) = 1.96-TeV

Description: We present a search for exclusive Z boson production in proton-antiproton collisions at {radical}s = 1.96 TeV, using the CDF II detector at Fermilab. We observe no exclusive Z {yields} {ell}{sup +}{ell}{sup -} candidates and place the first upper limit on the exclusive Z cross section in hadron collisions, {sigma}{sub excl}(Z) < 0.96 pb at 95% confidence level. In addition, we observe eight candidate exclusive dilepton events from the quantum electrodynamic process p{bar p} {yields} p{gamma}{gamma}{bar p} {yields} p{ell}{sup +}{ell}{sup -} {bar p}, and measure the cross section for M{sub {ell}{ell}} > 40 GeV=c{sup 2} and |{eta}{sub {ell}}| < 4 to be {sigma} = 0.24{sub -0.10}{sup +0.13} pb, which is the first measurement for this mass range and is consistent with the standard model prediction.
Date: February 1, 2009
Creator: Aaltonen, T.; Phys., /Helsinki Inst. of; Adelman, J.; /Chicago U., EFI; Akimoto, T.; U., /Tsukuba et al.
Partner: UNT Libraries Government Documents Department

Topologically induced local P and CP violation in hot QCD

Description: Very stringent experimental bounds exist on the amount of P and CP violation in strong interactions. Nevertheless, the presence of non-Abelian topological solutions and the axial anomaly make the issue of CP invariance in QCD non-trivial ('the strong CP problem'). Even in the absence of a global P and CP violation the fluctuations of topological charge in the QCD vacuum are expected to play an important role in the breaking of chiral symmetry, and in the mass spectrum and other properties of hadrons. Here I argue that topological fluctuations in hot QCD matter can become directly observable in the presence of a very intense external magnetic field by inducing local P- and CP-odd effects. These local parity-violating phenomena can be described by using the Maxwell-Chern-Simons, or axion, electrodynamics as an effective theory. Local P and CP violation in hot QCD matter can be observed in experiment through the 'chiral magnetic effect' - the separation of electric charge along the axis of magnetic field that is created by the colliding relativistic ions. There is a recent evidence for the electric charge separation relative to the reaction plane of heavy ion collisions from the STAR Collaboration at RHIC.
Date: February 1, 2009
Creator: Kharzeev,D.E.
Partner: UNT Libraries Government Documents Department

Non-equilibrium electrodynamics in the large N expansion

Description: An effective action technique for the time evolution of a closed system consisting of a mean field interacting with charged fluctuations is presented, and applied specifically to Quantum Electrodynamics. The effective action of QED is first developed in a systematic expansion in 1/N where N is the number of distinct fermion species. Then by making use of the Schwinger-Keldysh closed time path (CTP) formulation of field theory, causality of the resulting equations of motion is ensured. In QED this technique may be used to study the quantum non-equilibrium effects of pair creation in strong electric fields and the scattering and transport processes of a relativistic e{sup +}e{sup {minus}} plasma. Numerical results for these processes in lowest order are presented. The renormalization procedure, connection to quantum transport theory and extension to QCD and other applications of the method are also discussed.
Date: February 1, 1994
Creator: Mottola, E.
Partner: UNT Libraries Government Documents Department

Topics in gauge theories and the unification of elementary particle interactions. Progress report, February 1, 1992--January 31, 1993

Description: Work done on the following topics is summarized: (1) Coulomb potential in QED on the lattice; (2) Weyl cosmic strings and their consequences; (3) Interference between past and future events in {phi} {yields} K{bar K}; (4) Quantum effects of strong classical electromagnetic fields; (5) Application of computer algebra to calculations in supersymmetry and supergravity; (6) numerical studies of classical scalar {phi}{sup 4} field theory and related nonlinear {sigma}-models; (7) Analysis of a cubic model field theory; and, (8) Renormalization group analysis of unified gauge theories.
Date: February 1, 1993
Creator: Srivastava, Y. N. & Vaughn, M. T.
Partner: UNT Libraries Government Documents Department

Tests of QED (Quantum Electrodynamics) to fourth order in alpha in electron-positron collisions at 29 GeV

Description: Tests of Quantum Electrodynamics to order /alpha//sup 4/ in e/sup +/e/sup /minus// collisions using the ASP detector at PEP (/radical/s = 29 GeV) are presented. Measurements are made of e/sup +/e/sup /minus// /yields/ /gamma//gamma//gamma//gamma/, e/sup +/e/sup /minus// /yields/ e/sup +/e/sup /minus///gamma//gamma/ and e/sup +/e/sup /minus// /yields/ e/sup +/e/sup /minus//e/sup +/e/sup /minus// where all four final state particles are separated from the beam line and each other. These are the most precise and highest statistics measurements yet reported for these processes. The ratios of measured to predicted cross sections are /gamma//gamma//gamma//gamma/: 0.97 /plus minus/ 0.04 /plus minus/ 0.14 e/sup /+/e/sup /minus///gamma/gamma/: 0.94 /plus minus/ 0.03 /plus minus/ 0.03 e/sup +/e/sup /minus//e/sup +/e/sup /minus//: 1.01 /plus minus/ 0.02 /plus minus/ 0.04 where the first uncertainty is the systematic uncertainty, and the second is the statistical uncertainty. All measurements show good agreement with theoretical predictions. A Monte Carlo method for simulating multi-pole processes is also presented, along with applications to the e/sup +/e/sup /minus// /yields/ e/sup +/e/sup /minus///gamma//gamma/ and e/sup +/e/sup /minus// /yields/ /gamma//gamma//gamma//gamma/ processes. The first measurements of five-body /alpha//sup 5/ events (/sup 5//gamma/, e/sup +/e/sup /minus///gamma//gamma//gamma/ and e/sup +/e/sup /minus//e/sup +/ e/sup /minus///gamma/) and one candidate six-body /alpha//sup 6/event (e/sup +/e/sup /minus//4/gamma/) are reported. Both the /alpha//sup 5/ and /alpha//sup 6/ measurements agree with estimates of their cross sections. 20 refs., 34 figs., 14 tabs.
Date: February 1, 1989
Creator: Hawkins, C.A.
Partner: UNT Libraries Government Documents Department

Electrokinetic Power Generation from Liquid Water Microjets

Description: Although electrokinetic effects are not new, only recently have they been investigated for possible use in energy conversion devices. We have recently reported the electrokinetic generation of molecular hydrogen from rapidly flowing liquid water microjets [Duffin et al. JPCC 2007, 111, 12031]. Here, we describe the use of liquid water microjets for direct conversion of electrokinetic energy to electrical power. Previous studies of electrokinetic power production have reported low efficiencies ({approx}3%), limited by back conduction of ions at the surface and in the bulk liquid. Liquid microjets eliminate energy dissipation due to back conduction and, measuring only at the jet target, yield conversion efficiencies exceeding 10%.
Date: February 15, 2008
Creator: Duffin, Andrew M. & Saykally, Richard J.
Partner: UNT Libraries Government Documents Department