28,973 research outputs found
Consistent picture for the electronic structure around a vortex core in iron-based superconductors
Based on a two-orbital model and taking into account the presence of the
impurity, we studied theoretically the electronic structure in the vortex core
of the iron-Pnictide superconducting materials. The vortex is pinned when the
impurity is close to the vortex core. The bound states shows up for the
unpinned vortex and are wiped out by a impurity. Our results are in good
agreement with recent experiments and present a consistent explanation for the
different electronic structure of vortex core revealed by experiments on
different materials.Comment: 4 pages, 5 figure
X(1835): A Natural Candidate of 's Second Radial Excitation
Recently BES collaboration observed one interesting resonance X(1835). We
point out that its mass, total width, production rate and decay pattern favor
its assignment as the second radial excitation of meson very
naturally
Quasiparticle states around a nonmagnetic impurity in electron-doped iron-based superconductors with spin-density-wave order
The quasiparticle states around a nonmagnetic impurity in electron-doped
iron-based superconductors with spin-density-wave (SDW) order are investigated
as a function of doping and impurity scattering strength. In the undoped
sample, where a pure SDW state exists, two impurity-induced resonance peaks are
observed around the impurity site and they are shifted to higher (lower)
energies as the strength of the positive (negative) scattering potential (SP)
is increased. For the doped samples where the SDW order and the superconducting
order coexist, the main feature is the existence of sharp in-gap resonance
peaks whose positions and intensity depend on the strength of the SP and the
doping concentration. In all cases, the local density of states exhibits clear
symmetry. We also note that in the doped cases, the impurity will divide
the system into two sublattices with distinct values of magnetic order. Here we
use the band structure of a two-orbital model, which considers the asymmetry of
the As atoms above and below the Fe-Fe plane. This model is suitable to study
the properties of the surface layers in the iron-pnictides and should be more
appropriate to describe the scanning tunneling microscopy experiments.Comment: 11 pages, 18 figure
Low regularity solutions of two fifth-order KdV type equations
The Kawahara and modified Kawahara equations are fifth-order KdV type
equations and have been derived to model many physical phenomena such as
gravity-capillary waves and magneto-sound propagation in plasmas. This paper
establishes the local well-posedness of the initial-value problem for Kawahara
equation in with and the local well-posedness
for the modified Kawahara equation in with .
To prove these results, we derive a fundamental estimate on dyadic blocks for
the Kawahara equation through the multiplier norm method of Tao
\cite{Tao2001} and use this to obtain new bilinear and trilinear estimates in
suitable Bourgain spaces.Comment: 17page
General covariant Horava-Lifshitz gravity without projectability condition and its applications to cosmology
We consider an extended theory of Horava-Lifshitz gravity with the detailed
balance condition softly breaking, but without the projectability condition.
With the former, the number of independent coupling constants is significantly
reduced. With the latter and by extending the original foliation-preserving
diffeomorphism symmetry to include a local U(1)
symmetry, the spin-0 gravitons are eliminated. Thus, all the problems related
to them disappear, including the instability, strong coupling, and different
speeds in the gravitational sector. When the theory couples to a scalar field,
we find that the scalar field is not only stable in both the ultraviolet (UV)
and infrared (IR), but also free of the strong coupling problem, because of the
presence of high-order spatial derivative terms of the scalar field.
Furthermore, applying the theory to cosmology, we find that due to the
additional U(1) symmetry, the Friedmann-Robertson-Walker (FRW) universe is
necessarily flat. We also investigate the scalar, vector, and tensor
perturbations of the flat FRW universe, and derive the general linearized field
equations for each kind of the perturbations.Comment: 19 pages, comments are welcome!!
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