4,704 research outputs found
Statefinder diagnostic for the modified polytropic Cardassian universe
We apply the Statefinder diagnostic to the Modified Polytropic Cardassian
Universe in this work. We find that the Statefinder diagnostic is quite
effective to distinguish Cardassian models from a series of other cosmological
models. The plane is used to classify the Modified Polytropic Cardassian
models into six cases. The evolutionary trajectories in the plane for the
cases with different and reveal different evolutionary properties
of the universe. In addition, we combine the observational data, the
Cosmic Microwave Background (CMB) data and the Baryonic Acoustic Oscillation
(BAO) data to make a joint analysis. We find that \textbf{Case 2} can be
excluded at the 68.3% confidence level and any case is consistent with the
observations at the 95.4% confidence level.Comment: Comments: Final version for publication in Physical Review D [minor
revision to match the appear version] Journal-ref: Physical Review D 75,
083515 (2007
Solving the Dirac equation with nonlocal potential by Imaginary Time Step method
The Imaginary Time Step (ITS) method is applied to solve the Dirac equation
with the nonlocal potential in coordinate space by the ITS evolution for the
corresponding Schr\"odinger-like equation for the upper component. It is
demonstrated that the ITS evolution can be equivalently performed for the
Schr\"odinger-like equation with or without localization. The latter algorithm
is recommended in the application for the reason of simplicity and efficiency.
The feasibility and reliability of this algorithm are also illustrated by
taking the nucleus O as an example, where the same results as the
shooting method for the Dirac equation with localized effective potentials are
obtained
Emergent phases in a compass chain with multisite interactions
We study a dimerised spin chain with biaxial magnetic interacting ions in the
presence of an externally induced three-site interactions out of equilibrium.
In the general case, the three-site interactions play a role in renormalizing
the effective uniform magnetic field. We find that the existence of zero-energy
Majorana modes is intricately related to the sign of Pfaffian of the
Bogoliubov-de Gennes Hamiltonian and the relevant topological invariant.
In contrast, we show that an exotic spin liquid phase can emerge in the compass
limit through a Berezinskii-Kosterlitz-Thouless (BKT) quantum phase transition.
Such a BKT transition is characterized by a large dynamic exponent , and
the spin-liquid phase is robust under a uniform magnetic field. We find the
relative entropy and the quantum discord can signal the BKT transitions. We
also uncover a few differences in deriving the correlation functions for the
systems with broken reflection symmetry.Comment: 12 pages, 10 figure
Constraints on the DGP Universe using observational Hubble parameter
AbstractIn this work, we use observations of the Hubble parameter from the differential ages of passively evolving galaxies and the recent detection of the Baryon Acoustic Oscillations (BAO) at z1=0.35 to constrain the Dvali–Gabadadze–Porrati (DGP) Universe. For the case with a curvature term, we set a prior h=0.73±0.03 and the best-fit values suggest a spatially closed Universe. For a flat Universe, we set h free and we get consistent results with other recent analyses
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