26,019 research outputs found
Preparation and evaluation of fiber metal nickel battery plaques third quarterly progress report, feb. 1 - apr. 30, 1965
Effect of fiber size opon internal surface area and pore size of nickel fiber metal plaque
Optical Constants of Silver and Barium in the Vacuum Ultraviolet Spectral Region
Optical constants of silver and barium in vacuum ultraviolet spectral regio
Front Propagation up a Reaction Rate Gradient
We expand on a previous study of fronts in finite particle number
reaction-diffusion systems in the presence of a reaction rate gradient in the
direction of the front motion. We study the system via reaction-diffusion
equations, using the expedient of a cutoff in the reaction rate below some
critical density to capture the essential role of fl uctuations in the system.
For large density, the velocity is large, which allows for an approximate
analytic treatment. We derive an analytic approximation for the front velocity
depe ndence on bulk particle density, showing that the velocity indeed diverge
s in the infinite density limit. The form in which diffusion is impleme nted,
namely nearest-neighbor hopping on a lattice, is seen to have an essential
impact on the nature of the divergence
QCD traveling waves beyond leading logarithms
We derive the asymptotic traveling-wave solutions of the nonlinear
1-dimensional Balitsky-Kovchegov QCD equation for rapidity evolution in
momentum-space, with 1-loop running coupling constant and equipped with the
Balitsky-Kovchegov-Kuraev-Lipatov kernel at next-to-leading logarithmic
accuracy, conveniently regularized by different resummation schemes. Traveling
waves allow to define "universality classes" of asymptotic solutions, i.e.
independent of initial conditions and of the nonlinear damping. A dependence on
the resummation scheme remains, which is analyzed in terms of geometric scaling
properties.Comment: 10 pages, 5 figures; typos corrected, references updated, final
Phys.Rev. D versio
Charge dynamics of the spin-density-wave state in BaFeAs
We report on a thorough optical investigation of BaFeAs over a broad
spectral range and as a function of temperature, focusing our attention on its
spin-density-wave (SDW) phase transition at K. While
BaFeAs remains metallic at all temperatures, we observe a depletion in
the far infrared energy interval of the optical conductivity below ,
ascribed to the formation of a pseudogap-like feature in the excitation
spectrum. This is accompanied by the narrowing of the Drude term consistent
with the transport results and suggestive of suppression of scattering
channels in the SDW state. About 20% of the spectral weight in the far infrared
energy interval is affected by the SDW phase transition
Anisotropic charge dynamics in detwinned Ba(FeCo)As
We investigate the optical conductivity as a function of temperature with
light polarized along the in-plane orthorhombic - and -axes of
Ba(FeCo)As for =0 and 2.5 under uniaxial pressure.
The charge dynamics at low frequencies on these detwinned, single domain
compounds tracks the anisotropic transport properties across their
structural and magnetic phase transitions. Our findings allow us to estimate
the dichroism, which extends to relatively high frequencies. These results are
consistent with a scenario in which orbital order plays a significant role in
the tetragonal-to-orthorhombic structural transition
Critical conductance of a one-dimensional doped Mott insulator
We consider the two-terminal conductance of a one-dimensional Mott insulator
undergoing the commensurate-incommensurate quantum phase transition to a
conducting state. We treat the leads as Luttinger liquids. At a specific value
of compressibility of the leads, corresponding to the Luther-Emery point, the
conductance can be described in terms of the free propagation of
non-interacting fermions with charge e/\sqrt{2}. At that point, the temperature
dependence of the conductance across the quantum phase transition is described
by a Fermi function. The deviation from the Luther-Emery point in the leads
changes the temperature dependence qualitatively. In the metallic state, the
low-temperature conductance is determined by the properties of the leads, and
is described by the conventional Luttinger liquid theory. In the insulating
state, conductance occurs via activation of e/\sqrt{2} charges, and is
independent of the Luttinger liquid compressibility.Comment: 13 pages, 3 figures. Published versio
The application of the global isomorphism to the surface tension of the liquid-vapor interface of the Lennard-Jones fluids
In this communication we show that the surface tension of the real fluids of
the Lennard-Jones type can be obtained from the surface tension of the lattice
gas (Ising model) on the basis of the global isomorphism approach developed
earlier for the bulk properties.Comment: 8 pages, 6 figure
Universality and tree structure of high energy QCD
Using non-trivial mathematical properties of a class of nonlinear evolution
equations, we obtain the universal terms in the asymptotic expansion in
rapidity of the saturation scale and of the unintegrated gluon density from the
Balitsky-Kovchegov equation. These terms are independent of the initial
conditions and of the details of the equation. The last subasymptotic terms are
new results and complete the list of all possible universal contributions.
Universality is interpreted in a general qualitative picture of high energy
scattering, in which a scattering process corresponds to a tree structure
probed by a given source.Comment: 4 pages, 3 figure
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