36,097 research outputs found
Superfluidity of hyperons in neutron stars
We study the superfluidity of hyperons in neutron star
matter and neutron stars. We use the relativistic mean field (RMF) theory to
calculate the properties of neutron star matter. In the RMF approach, the
meson-hyperon couplings are constrained by reasonable hyperon potentials that
include the updated information from recent developments in hypernuclear
physics. To examine the pairing gap of hyperons, we employ
several interactions based on the Nijmegen models and used in
double- hypernuclei studies. It is found that the maximal pairing gap
obtained is a few tenths of a MeV. The magnitude and the density region of the
pairing gap are dependent on the interaction and the treatment
of neutron star matter. We calculate neutron star properties and find that
whether the superfluidity of hyperons exists in the core of
neutron stars mainly depends on the interaction used.Comment: 22 pages, 2 Tables, 6 Figur
Anomalous high energy dispersion in photoemission spectra from insulating cuprates
Angle resolved photoelectron spectroscopic measurements have been performed
on an insulating cuprate Ca_2CuO_2Cl_2. High resolution data taken along the
\Gamma to (pi,pi) cut show an additional dispersive feature that merges with
the known dispersion of the lowest binding energy feature, which follows the
usual strongly renormalized dispersion of ~0.35 eV. This higher energy part
reveals a dispersion that is very close to the unrenormalized band predicted by
band theory. A transfer of spectral weight from the low energy feature to the
high energy feature is observed as the \Gamma point is approached. By comparing
with theoretical calculations the high energy feature observed here
demonstrates that the incoherent portion of the spectral function has
significant structure in momentum space due to the presence of various energy
scales.Comment: 5 pages, 3 figure
On Algorithmic Statistics for space-bounded algorithms
Algorithmic statistics studies explanations of observed data that are good in
the algorithmic sense: an explanation should be simple i.e. should have small
Kolmogorov complexity and capture all the algorithmically discoverable
regularities in the data. However this idea can not be used in practice because
Kolmogorov complexity is not computable.
In this paper we develop algorithmic statistics using space-bounded
Kolmogorov complexity. We prove an analogue of one of the main result of
`classic' algorithmic statistics (about the connection between optimality and
randomness deficiences). The main tool of our proof is the Nisan-Wigderson
generator.Comment: accepted to CSR 2017 conferenc
Measurement of a Sign-Changing Two-Gap Superconducting Phase in Electron-Doped Ba(Fe_{1-x}Co_x)_2As_2 Single Crystals using Scanning Tunneling Spectroscopy
Scanning tunneling spectroscopic studies of (x =
0.06, 0.12) single crystals reveal direct evidence for predominantly two-gap
superconductivity. These gaps decrease with increasing temperature and vanish
above the superconducting transition . The two-gap nature and the slightly
doping- and energy-dependent quasiparticle scattering interferences near the
wave-vectors and are consistent with
sign-changing -wave superconductivity. The excess zero-bias conductance and
the large gap-to- ratios suggest dominant unitary impurity scattering.Comment: 4 pages, 4 figures. Paper accepted for publication in Physical Review
Letters. Contact author: Nai-Chang Yeh ([email protected]
Reversible Fluorination of Graphene: towards a Two-Dimensional Wide Bandgap Semiconductor
We report the synthesis and evidence of graphene fluoride, a two-dimensional
wide bandgap semiconductor derived from graphene. Graphene fluoride exhibits
hexagonal crystalline order and strongly insulating behavior with resistance
exceeding 10 G at room temperature. Electron transport in graphene
fluoride is well described by variable-range hopping in two dimensions due to
the presence of localized states in the band gap. Graphene obtained through the
reduction of graphene fluoride is highly conductive, exhibiting a resistivity
of less than 100 k at room temperature. Our approach provides a new
path to reversibly engineer the band structure and conductivity of graphene for
electronic and optical applications.Comment: 7 pages, 5 figures, revtex, to appear in PR
- …