Zobrazeno 1 - 10
of 1 939
pro vyhledávání: '"Kleinert H"'
Autor:
Kleinert, H., Zatloukal, V.
Publikováno v:
Phys. Rev. E 88, 052106 (2013)
The statistics of rare events, the so-called black-swan events, is governed by non-Gaussian distributions with heavy power-like tails. We calculate the Green functions of the associated Fokker-Planck equations and solve the related stochastic differe
Externí odkaz:
http://arxiv.org/abs/1503.01667
We discuss the BCS theory for electrons in graphene with a superimposed electrical unidirectional superlattice potential (SL). New Dirac points emerge together with van Hove singularities (VHS) linking them. We obtain a superconducting transition tem
Externí odkaz:
http://arxiv.org/abs/1310.5565
Autor:
Kleinert, H.
While free and weakly interacting nonrelativistic particles are described by a Gross-Pitaevskii equation, which is a nonlinear self-interacting Schr\"odinger equation, the phenomena in the strong- coupling limit are governed by an effective action th
Externí odkaz:
http://arxiv.org/abs/1307.4547
Autor:
Kleinert, H.
We show that a triangular lattice consisting of dipolar molecules pointing orthogonal to the plane undergoes a first-order defect melting transition.
Comment: 6 pages
Comment: 6 pages
Externí odkaz:
http://arxiv.org/abs/1306.6449
Publikováno v:
J.STAT. Mech. ,P01003 (2014)
We formulate the Collective Quantum Field Theory for three-dimensional bosonic optical lattices and evaluate its consequences in a mean-field approximation to two collective fields, proposed by Fred Cooper et al. and in a lowest-order Variational Per
Externí odkaz:
http://arxiv.org/abs/1303.1642
Autor:
Kleinert, H.
Publikováno v:
EPL, 100 (2012) 10001
While free and weakly interacting particles are well described by a a second-quantized nonlinear Schr\"odinger field, or relativistic versions of it, the fields of strongly interacting particles are governed by effective actions, whose quadratic term
Externí odkaz:
http://arxiv.org/abs/1210.2630
Autor:
Chervyakov, A., Kleinert, H.
A detailed analysis of electron-positron pair creation induced by a spatially nonuniform and static electric field from vacuum is presented. A typical example is provided by the Sauter potential. For this potential, we derive the analytic expressions
Externí odkaz:
http://arxiv.org/abs/1112.4120
Publikováno v:
Phys. Rev. A 85, 063602 (2012)
We study the quantum phase transition in optical lattices using ordinary Bose Hubbard Hamiltonian within two loop approximation in variational perturbation theory. We have shown that this approximation can reproduce superfluid Mott insulator transiti
Externí odkaz:
http://arxiv.org/abs/1108.4695
Autor:
Kleinert, H.
Publikováno v:
EJTP 8, 57 (2011)
We recall the successes of the Hubbard-Stratonovich Transformation (HST) of many-body theory, point out its failure to cope with competing channels of collective phenomena and show how to overcome this by Variational Perturbation Theory. That yields
Externí odkaz:
http://arxiv.org/abs/1104.5161
Autor:
Kleinert, H.
Publikováno v:
EJTP 8, 15 (2011)
With the help of a simple variational procedure it is possible to convert the partial sums of order $N$ of many divergent series expansions $f(g)=\sum_{n=0}^\infty a_n g^n$ into partial sums $\sum_{n=0}^N b_n g^{- \omega n}$, where $0<\omega<1$ is a
Externí odkaz:
http://arxiv.org/abs/1006.2910