UScholar Works
 
Filters: Department: "Physics" Format: "application/pdf" School Or College: "College of Science" Collection: "ir_uspace"
676 - 700 of 924
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CreatorTitleDescriptionSubjectDate
676 Wu, Yong-ShiRenormalization group equations and the Lifshitz point in noncommutative Landau-Ginsburg theoryA one-loop renormalization group (RG) analysis is performed for noncommutative Landau-Ginsburg theory in an arbitrary dimension. We adopt a modern version of the Wilsonian RG approach, in which a shell integration in momentum space bypasses the potential IR singularities due to UV-IR mixing. The mo...2002-02
677 Wu, Yong-ShiRenormalization of the statistics parameter in three-dimensional electrodynamicsWe argue that the p function for the statistics parameter in (2+1)-dimensional electrodynamics is zero to all orders in perturbation theory beyond one loop. We show that there can be finite radiative corrections from massless charged scalar fields.Renormalization1989-02
678 Wu, Yong-ShiResonant above-threshold ionization at quantized laser intensitiesWe argue that quantum electrodynamics dictates resonance phenomena in multiphoton processes as the laser intensity varies. A perturbation theory is developed in which the coupling between an electron and the second quantized laser mode is treated nonperturbatively. As an example, we predict that th...Laser field; Volkov states2000-03
679 Mishchenko, EugeneResonant finite-size impurities in graphene, unitary limit, and Friedel oscillationsA unitary limit for model point scatterers in graphene is known to reveal low-energy resonances. The same limit could be achieved from hybridization of band electrons with the localized impurity level positioned in the vicinity of the Fermi level. The finite-size defects represent an easier realizat...2012-01-01
680 Vardeny, Zeev Valentine; Ehrenfreund, Eitan A.Resonant Raman scattering from amplitude modes in trans-(CH)x and -(CD)xThe three resonantly enhanced Raman vibrations in trans-(CK)x and ~(CD)X are described in terms of amplitude modes associated with the Peierls gap. The dispersion in the Raman-line profiles is explained by inhomogeneity. A narrow distribution of the effective electron-phonon coupling constant is re...Peierls gap1983-12
681 Vardeny, Zeev ValentineResonant Raman-scattering spectroscopy of polydiacetylene films at high pressureWe studied the electronic energies and phonon frequencies of polydiacetylene 4-BCMU thin films at high pressures up to 50 kbar using Raman scattering under preresonant and resonant conditions. Pressure-induced changes in the resonant Raman scattering (RRS) include (1) hardening of the most strongly...Resonant raman scattering spectroscopy; Polydiacetylene films; Pi-conjugated polymers1993-02
682 Vardeny, Zeev ValentineResonant-Raman-scattering studies of disorder in solution-cast polydiacetylene filmsThe disorder in polydiacetylene films cast from solution is studied by Raman scattering under preresonance and resonance conditions in both Stokes and anti-Stokes configurations. The disorder-induced inhomogeneities in the exciton energy levels and the strongly coupled vibrations cause strong disper...Polydiacetylene films; Stokes configuration1990-08
683 Vardeny, Zeev Valentine; Nahata, AjayResonantly-enhanced transmission through a periodic array of subwavelength apertures in heavily-doped conducting polymer filmsWe observed resonantly-enhanced terahertz transmission through two-dimensional (2D) periodic arrays of subwavelength apertures with various periodicities fabricated on metallic organic conducting polymer films of polypyrrole heavily doped with PF6 molecules [PPy(PF6)]. The"anomalous transmission" s...Resonantly enhanced transmission; Subwavelength apertures; Polypyrrole; PPy(PF6)2006
684 DeTar, CarletonResults for light pseudoscalars from three-flavor simulationsWe compute pseudoscalar meson masses and decay constants in partially quenched QCD with three dynamical flavors of improved staggered quarks. Fitting the lattice data to staggered chiral perturbation theory (SX_x001F_PT) forms and extrapolating in quark mass and lattice spacing, we find: frr = 129...Pseudoscalars; Decay constants; Staggered quarks2005-03
685 Vardeny, Zeev ValentineRing microlasers from conducting polymersWe demonstrate pulsed, photopumped multimode laser emission in the visible spectral range from cylindrical microcavities formed by conducting polymer thin films deposited around optical fibers. The laser is characterized by narrow emission lines (~1.5 cm-1), a well-defined excitation threshold, an...Ring microlasers; Laser emission; Waveguided ring modes; Whispering gallery modes1997-08
686 Gondolo, PaoloRing-like features in directional dark matter detectionWe discuss a novel dark matter signature relevant for directional detection of Weakly Interacting Massive Particles (WIMPs). For heavy enough WIMPs and low enough recoil energies, the maximum of the recoil rate is not in the direction of the average WIMP arrival direction but in a ring around it at ...2012-01-01
687 Bromley, Benjamin C.Rise and fall of debris disks: MIPS observations of h and chi Persei and the evolution of mid-IR emission from planet formationWe describe Spitzer MIPS observations of the double cluster, h and X Persei, covering a 0.6 deg2 area surrounding the cores of both clusters. The data are combined with IRAC and 2MASS data to investigate 616 sources from 1.25Y24 m. We use the long-baseline Ks ½24 color to identify two population...Infrared circumstellar matter; Open clusters and associations stars: Individual (NGC 869, NGC 884) planetary systems: Formation, planetary systems: Protoplanetary disks2008
688 DeTar, CarletonRole of baryons in chiral-symmetry restoration at high temperatureTo help provide insight into the apparent remarkable rise in baryon susceptibility at the high-temperature phase transition in QCD, we study the three-dimensional lattice SU(2) chiral model at finite temperature. The purpose of this study is to determine the extent to which a rising susceptibility i...Chiral model; Chiral symmetry; Quark plasma; Skyrmions; Phase transitions1990-07
689 Mattis, Daniel C.Role of Fermi surface and crystal structure in theory of magnetic metalsWe have investigated the magnetic ground state of metals using an idealized theory of magnetism based on the Ruderman-Kittel-Yosida indirect exchange interaction. The preliminary, but suggestive, results reported here are for simple cubic structures and spherical Fermi surface. We find that as the...Magnetic metals; Crystal structure1962-11
690 Mattis, Daniel C.Role of phonons and band structure in metal-insulator phase transitionWe present a soluble model of electrons interacting with lattice vibrations which displays metallic, superconducting, and insulating phases. We solve the thermodynamics of this model and discuss its properties. The metal-insulator phase transition is second order for sc and bcc tight-binding bands. ...Band structure1970-08
691 Wu, Yong-Shi; Raikh, Mikhail E.Role of spin-orbit coupling in the metal-insulator transition in two-dimensional systemsWe propose an experiment, which would allow us to pinpoint the role of spin-orbit coupling in the metal-nonmetal transition observed in a number of two-dimensional systems at low densities. Namely, we demonstrate that in a parallel magnetic field the interplay between the spin-orbit coupling and the...Spin-orbit coupling; Metal-insulator transitions2000-04
692 Boehme, ChristophRoom temperature electrical detection of spin coherence in C60An experimental demonstration of electrical detection of coherent spin motion of weakly coupled, localized electron spins in thin fullerene C60 films at room temperature is presented. Pulsed electrically detected magnetic resonance experiments on vertical photocurrents through Al/C60/ZnO samples sh...Spin coherence2007-05
693 Lupton, John MarkRoom-temperature exciton storage in elongated semiconductor nanocrystalsThe excited state of colloidal nanoheterostructures consisting of a spherical CdSe nanocrystal with an epitaxially attached CdS rod can be perturbed effectively by electric fields. Field-induced fluorescence quenching coincides with a conversion of the excited state species from the bright exciton ...Exciton storage; Colloidal nanoheterostructures; CdSe nanocrystal2007-01
694 DeTar, CarletonScalar meson spectroscopy with lattice staggered fermionsWith sufficiently light up and down quarks the isovector (a0) and isosinglet (f0) scalar meson propagators are dominated at large distance by two-meson states. In the staggered-fermion formulation of lattice quantum chromodynamics, taste-symmetry breaking causes a proliferation of two-meson states t...Staggered fermions; Chiral theory2007-11
695 Wu, Yong-ShiScale and conformal invariance in Chern-Simons-matter field theoryWe study perturbative renormalization of Dsss3 Chern-Simons gauge theory coupled to scalar and fermionic matter. We show that in the non-Abelian case the coefficient of the Chern-Simons term has infinite renormalization and that both the matter and the non-Abelian gauge fields acquire nonvanishing ...Chern-Simons gauge theory; Renormalization1991-09
696 DeTar, CarletonScaling and eigenmode tests of the improved fat clover actionWe test a recently proposed improved lattice-fermion action, the fat link clover action, examining indicators of pathological small-quark-mass lattice artifacts (‘‘exceptional configurations'') on quenched lattices of spacing 0.12 fm and studying scaling properties of the light hadron spectrum ...Clover actions; Wilson actions2000-12
697 DeTar, CarletonScaling tests of the improved Kogut-Susskind quark actionImproved lattice actions for Kogut-Susskind quarks have been shown to improve rotational symmetry and flavor symmetry. In this work we find improved scaling behavior of the r and nucleon masses expressed in units of a length scale obtained from the static quark potential, and better behavior of the ...Instantons; Static potential2000-04
698 Williams, Clayton C.Scanning capacitance microscope methodology for quantitative analysis of P-N junctionsQuantification of dopant profiles in two dimensions (2D) for p-n junctions has proven to be a challenging problem. The scanning capacitance microscope (SCM) capability for p-n junction imaging has only been qualitatively demonstrated. No well-established physical model exists yet for the SCM data in...p-n junctions; Scanning capacitance microscope; SCM1999
699 Williams, Clayton C.Scanning capacitance microscopy on a 25 nm scaleA near-field capacitance microscope has been demonstrated on a 25 nm scale. A resonant circuit provides the means for sensing the capacitance variations between a sub-lGO-nra tip and surface with a sensitivity of 1X 10 19 F in a I kHz bandwidth. Feedback control is used to scan the tip at constant g...Scanning capacitance microscopy1989
700 Williams, Clayton C.Scanning thermal profilerA new high-resolution profilometer has been demonstrated based upon a noncontacting nearfield thermal probe. The thermal probe consists of a thermocouple sensor with dimensions approaching 100 nm. Profiling is achieved by scanning the heated sensor above but close to the surface of a solid. The con...Thermal probe; Scanning thermal profiler1986
676 - 700 of 924