24,536 research outputs found
Global Existence and Uniqueness of Solutions to the Maxwell-Schr{\"o}dinger Equations
The time local and global well-posedness for the Maxwell-Schr{\"o}dinger
equations is considered in Sobolev spaces in three spatial dimensions. The
Strichartz estimates of Koch and Tzvetkov type are used for obtaining the
solutions in the Sobolev spaces of low regularities. One of the main results is
that the solutions exist time globally for large data.Comment: 30 pages. In the revised version, the following modification was
made. (1) A line for dedication was added in the first page. (2) Some lines
were added at the bottom in page 4 and the top in page 5 in the first section
to make the description accurate. (3) Some typographical errors were
corrected throughout the pape
QED Radiative Corrections to the Non-annihilation Processes Using the Structure Function and the Parton Shower
Inclusion of the QED higher order radiative corrections in the two-photon
process, e+e- -> e+e- mu+mu-, is examined by means of the structure function
and the parton shower. Results are compared with the exact
calculations and give a good agreement. These two methods should be universally
applicable to any other non-annihilation processes like the single-W
productions in the e+e- collisions. In this case, however, the energy scale for
the evolution by the renormalization-group equation should be chosen properly
depending on the dominant diagrams for the given process. A method to find the
most suitable energy scale is proposed.Comment: 17 pages, LaTeX, 5 figure
Sintering behavior of ultrafine silicon carbide powders obtained by vapor phase reaction
The sintering behavior of ultrafine SiC powder with average particle size of about 0.01-0.06 microns produced by a vapor phase reaction of the Me4Si-H2 system was studied at the temperature range of 1400-2050 deg. It was found that the homogeneous dispersion of C on SiC particles is important to remove the surface oxide layer effectively. B and C and inhibitive effect on SiC grain growth
Superconductivity in heavily boron-doped silicon carbide
The discoveries of superconductivity in heavily boron-doped diamond (C:B) in
2004 and silicon (Si:B) in 2006 renew the interest in the superconducting state
of semiconductors. Charge-carrier doping of wide-gap semiconductors leads to a
metallic phase from which upon further doping superconductivity can emerge.
Recently, we discovered superconductivity in a closely related system:
heavily-boron doped silicon carbide (SiC:B). The sample used for that study
consists of cubic and hexagonal SiC phase fractions and hence this lead to the
question which of them participates in the superconductivity. Here we focus on
a sample which mainly consists of hexagonal SiC without any indication for the
cubic modification by means of x-ray diffraction, resistivity, and ac
susceptibility.Comment: 9 pages, 5 figure
QED Radiative Correction for the Single-W Production using a Parton Shower Method
A parton shower method for the photonic radiative correction is applied to
the single W-boson production processes. The energy scale for the evolution of
the parton shower is determined so that the correct soft-photon emission is
reproduced. Photon spectra radiated from the partons are compared with those
from the exact matrix elements, and show a good agreement. Possible errors due
to a inappropriate energy-scale selection or due to the ambiguity of energy
scale determination are also discussed, particularly for the measurements on
triple gauge-couplings.Comment: 17 pages, 6 Postscript figure
Effects of Rattling Phonons on the Quasiparticle Excitation and Dynamics in the Superconducting -Pyrochlore KOsO
Microwave penetration depth and surface resistance at 27 GHz are
measured in high quality crystals of KOsO. Firm evidence for
fully-gapped superconductivity is provided from . Below the second
transition at K, the superfluid density shows a step-like
change with a suppression of effective critical temperature .
Concurrently, the extracted quasiparticle scattering time shows a steep
enhancement, indicating a strong coupling between the anomalous rattling motion
of K ions and quasiparticles. The results imply that the rattling phonons help
to enhance superconductivity, and that K sites freeze to an ordered state with
long quasiparticle mean free path below .Comment: 5 pages, 5 figures, to be published in Phys. Rev. Let
Derivation of Green's Function of Spin Calogero-Sutherland Model by Uglov's Method
Hole propagator of spin 1/2 Calogero-Sutherland model is derived using
Uglov's method, which maps the exact eigenfunctions of the model, called
Yangian Gelfand-Zetlin basis, to a limit of Macdonald polynomials (gl_2-Jack
polynomials). To apply this mapping method to the calculation of 1-particle
Green's function, we confirm that the sum of the field annihilation operator on
Yangian Gelfand-Zetlin basis is transformed to the field annihilation operator
on gl_2-Jack polynomials by the mapping. The resultant expression for hole
propagator for finite-size system is written in terms of renormalized momenta
and spin of quasi-holes and the expression in the thermodynamic limit coincides
with the earlier result derived by another method. We also discuss the
singularity of the spectral function for a specific coupling parameter where
the hole propagator of spin Calogero-Sutherland model becomes equivalent to
dynamical colour correlation function of SU(3) Haldane-Shastry model.Comment: 36 pages, 8 figure
grc4f v1.0: a Four-fermion Event Generator for e+e- Collisions
grc4f is a Monte-Carlo package for generating e+e- to 4-fermion processes in
the standard model. All of the 76 LEP-2 allowed fermionic final state processes
evaluated at tree level are included in version 1.0. grc4f addresses event
simulation requirements at e+e- colliders such as LEP and up-coming linear
colliders. Most of the attractive aspects of grc4f come from its link to the
GRACE system: a Feynman diagram automatic computation system. The GRACE system
has been used to produce the computational code for all final states, giving a
higher level of confidence in the calculation correctness. Based on the
helicity amplitude calculation technique, all fermion masses can be kept finite
and helicity information can be propagated down to the final state particles.
The phase space integration of the matrix element gives the total and
differential cross sections, then unweighted events are Generated. Initial
state radiation (ISR) corrections are implemented in two ways, one is based on
the electron structure function formalism and the second uses the parton shower
algorithm called QEDPS. The latter can also be applied for final state
radiation (FSR) though the interference with the ISR is not yet taken into
account. Parton shower and hadronization of the final quarks are performed
through an interface to JETSET. Coulomb correction between two intermediate
W's, anomalous coupling as well as gluon contributions in the hadronic
processes are also included.Comment: 30 pages, LaTeX, 5 pages postscript figures, uuencode
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