4,253 research outputs found
A flexible and adaptive Simpler GMRES with deflated restarting for shifted linear systems
In this paper, two efficient iterative algorithms based on the simpler GMRES
method are proposed for solving shifted linear systems. To make full use of the
shifted structure, the proposed algorithms utilizing the deflated restarting
strategy and flexible preconditioning can significantly reduce the number of
matrix-vector products and the elapsed CPU time. Numerical experiments are
reported to illustrate the performance and effectiveness of the proposed
algorithms.Comment: 17 pages. 9 Tables, 1 figure; Newly update: add some new numerical
results and correct some typos and syntax error
Diffusion in higher dimensional SYK model with complex fermions
We construct a new higher dimensional SYK model with complex fermions on
bipartite lattices. As an extension of the original zero-dimensional SYK model,
we focus on the one-dimension case, and similar Hamiltonian can be obtained in
higher dimensions. This model has a conserved U(1) fermion number Q and a
conjugate chemical potential \mu. We evaluate the thermal and charge diffusion
constants via large q expansion at low temperature limit. The results show that
the diffusivity depends on the ratio of free Majorana fermions to Majorana
fermions with SYK interactions. The transport properties and the butterfly
velocity are accordingly calculated at low temperature. The specific heat and
the thermal conductivity are proportional to the temperature. The electrical
resistivity also has a linear temperature dependence term.Comment: 15 pages, 1 figure, add 4 references and fix some typos in this
versio
Transport Coefficients for Holographic Hydrodynamics at Finite Energy Scale
We investigate the relations between black hole thermodynamics and
holographic transport coefficients in this paper. The formulae for DC
conductivity and diffusion coefficient are verified for electrically
single-charged black holes. We examine the correctness of the proposed
expressions by taking charged dilatonic and single-charged STU black holes as
two concrete examples, and compute the flows of conductivity and diffusion
coefficient by solving the linear order perturbation equations. We then check
the consistence by evaluating the Brown-York tensor at a finite radial
position. Finally, we find that the retarded Green functions for the shear
modes can be expressed easily in terms of black hole thermodynamic quantities
and transport coefficients.Comment: 33 pages,4 figures,to appear in Advances in High Energy Physic
Van der Waals-like phase transition from holographic entanglement entropy in Lorentz breaking massive gravity
In this paper, phase transition of AdS black holes in lorentz breaking
massive gravity has been studied in the framework of holography. We find that
there is a first order phase transition(FPT) and second order phase
transition(SPT) both in Bekenstein-Hawking entropy(BHE)-temperature plane and
holographic entanglement entropy(HEE)-temperature plane. Furthermore, for the
FPT, the equal area law is checked and for the SPT, the critical exponent of
the heat capacity is also computed. Our results confirm that the phase
structure of HEE is similar to that of BHE in lorentz breaking massive gravity,
which implies that HEE and BHE have some potential underlying relationship.Comment: 10 pages, 10 figure
Magnetothermoelectric DC conductivities from holography models with hyperscaling factor in Lifshitz spacetime
We investigate an Einstein-Maxwell-Dilaton-Axion holographic model and obtain
two branches of a charged black hole solution with a dynamic exponent and a
hyperscaling violation factor when a magnetic field presents. The
magnetothermoelectric DC conductivities are then calculated in terms of horizon
data by means of holographic principle. We find that linear temperature
dependence resistivity and quadratic temperature dependence inverse Hall angle
can be achieved in our model. The well-known anomalous temperature scaling of
the Nernst signal and the Seebeck coefficient of cuprate strange metals are
also discussed.Comment: 1+23 pages, 4 figures, references adde
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