4,105 research outputs found
Exploring the evolution of color-luminosity parameter and its effects on parameter estimation
It has been found in previous studies that, for the Supernova Legacy Survey
three-year (SNLS3) data, there is strong evidence for the redshift-evolution of
color-luminosity parameter . In this paper, using three simplest dark
energy models (CDM, CDM, and CPL), we further explore the evolution
of and its effects on parameter estimation. In addition to the SNLS3
data, we also take into account the Planck distance priors data, as well as the
latest galaxy clustering (GC) data extracted from SDSS DR7 and BOSS. We find
that, for all the models, adding a parameter of can reduce
by 36, indicating that is ruled out at
6 confidence levels. In other words, deviates from a constant
at 6 confidence levels. This conclusion is insensitive to the dark
energy models considered, showing the importance of considering the evolution
of in the cosmology-fits. Furthermore, it is found that varying
can significantly change the fitting results of various cosmological
parameters: using the SNLS3 data alone, varying yields a larger
for the CDM model; using the SNLS3+CMB+GC data, varying
yields a larger and a smaller for all the models.
Moreover, we find that these results are much closer to those given by the
CMB+GC data, compared to the cases of treating as a constant. This
indicates that considering the evolution of is very helpful for
reducing the tension between supernova and other cosmological observations.Comment: 11 pages, 9 figures, 2 tables; accepted for publication in Physical
Review D. arXiv admin note: text overlap with arXiv:1306.6423; and with
arXiv:1109.3172 by other author
Enhanced Feedback Iterative Decoding of Sparse Quantum Codes
Decoding sparse quantum codes can be accomplished by syndrome-based decoding
using a belief propagation (BP) algorithm.We significantly improve this
decoding scheme by developing a new feedback adjustment strategy for the
standard BP algorithm. In our feedback procedure, we exploit much of the
information from stabilizers, not just the syndrome but also the values of the
frustrated checks on individual qubits of the code and the channel model.
Furthermore we show that our decoding algorithm is superior to belief
propagation algorithms using only the syndrome in the feedback procedure for
all cases of the depolarizing channel. Our algorithm does not increase the
measurement overhead compared to the previous method, as the extra information
comes for free from the requisite stabilizer measurements.Comment: 10 pages, 11 figures, Second version, To be appeared in IEEE
Transactions on Information Theor
Phase Transition of Finite Size Quark Droplets with Isospin Chemical Potential in the Nanbu--Jona-Lasinio Model
Making use of the NJL model and the multiple reflection expansion
pproximation, we study the phase transition of the finite size droplet with u
and d quarks. We find that the dynamical masses of u, d quarks are different,
and the chiral symmetry can be restored at different critical radii for u, d
quark. It rovides a clue to understand the effective nucleon mass splitting in
nuclear matter. Meanwhile, it shows that the maximal isospin chemical potential
at zero temperature is much smaller than the mass of pion in free space.Comment: 12 pages, 3 figures. To appear in Physical Review
Central Limit Theorem for m-dependent random variables under sub-linear expectations
M-dependence is a commonly used assumption in the study of dependent
sequences. In this paper, central limit theorems for m-dependent random
variables under the sub-linear expectations are established based mainly on the
conditions of Zhang. They can be regarded as the extension of independent
Lindeberg central limit theorem and for proving this, Rosenthal's inequality
for m-dependent random variables is obtained. In particular, we extend the
results in Li and establish the central limit theorem for m-dependent
stationary sequence.Comment: 15page
A closer look at interacting dark energy with statefinder hierarchy and growth rate of structure
We investigate the interacting dark energy models by using the diagnostics of
statefinder hierarchy and growth rate of structure. We wish to explore the
deviations from CDM and to differentiate possible degeneracies in the
interacting dark energy models with the geometrical and structure growth
diagnostics. We consider two interacting forms for the models, i.e., and , with being the dimensionless
coupling parameter. Our focus is the ICDM model that is a
one-parameter extension to CDM by considering a direct coupling
between the vacuum energy () and cold dark matter (CDM), with the only
additional parameter . But we begin with a more general case by
considering the ICDM model in which dark energy has a constant
(equation-of-state parameter). For calculating the growth rate of structure, we
employ the "parametrized post-Friedmann" theoretical framework for interacting
dark energy to numerically obtain the values for the models. We
show that in both geometrical and structural diagnostics the impact of is
much stronger than that of in the ICDM model. We thus wish to have a
closer look at the ICDM model by combining the geometrical and
structural diagnostics. We find that the evolutionary trajectories in the
-- plane exhibit distinctive features and the departures
from CDM could be well evaluated, theoretically, indicating that the
composite null diagnostic is a promising tool for
investigating the interacting dark energy models.Comment: 17 pages, 4 figures; accepted for publication in JCA
Possible singlet and triplet superconductivity on honeycomb lattice
We study the possible superconducting pairing symmetry mediated by spin and
charge fluctuations on the honeycomb lattice using the extended Hubbard model
and the random-phase-approximation method. From to doping levels,
a spin-singlet -wave is shown to be the leading
superconducting pairing symmetry when only the on-site Coulomb interaction
is considered, with the gap function being a mixture of the nearest-neighbor
and next-nearest-neighbor pairings. When the offset of the energy level between
the two sublattices exceeds a critical value, the most favorable pairing is a
spin-triplet -wave which is mainly composed of the next-nearest-neighbor
pairing. We show that the next-nearest-neighbor Coulomb interaction is also
in favor of the spin-triplet -wave pairing.Comment: 6 pages, 4 figure
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