412 research outputs found
Heat Kernel Expansion for Operators of the Type of the Square Root of the Laplace Operator
A method is suggested for the calculation of the DeWitt-Seeley-Gilkey (DWSG)
coefficients for the operator basing on a
generalization of the pseudodifferential operator technique. The lowest DWSG
coefficients for the operator are calculated by using
the method proposed. It is shown that the method admits a generalization to the
case of operators of the type , where m is an
arbitrary rational number. A more simple method is proposed for the calculation
of the DWSG coefficients for the case of strictly positive operators under the
sign of root. By using this method, it is shown that the problem of the
calculation of the DWSG coefficients for such operators is exactly solvable.
Namely, an explicit formula expressing the DWSG coefficients for operators with
root through the DWSG coefficients for operators without root is deduced.Comment: 17 pages, LaTeX, no figure
Dynamics and phase diagram of the quantum Hall state in bilayer graphene
Utilizing the Baym-Kadanoff formalism with the polarization function
calculated in the random phase approximation, the dynamics of the
quantum Hall state in bilayer graphene is analyzed. Two phases with nonzero
energy gap, the ferromagnetic and layer asymmetric ones, are found. The phase
diagram in the plane , where is a
top-bottom gates voltage imbalance, is described. It is shown that the energy
gaps in these phases scale linearly, $\Delta E\sim 10 B[T]K, with magnetic
field. The comparison of these results with recent experiments in bilayer
graphene is presented.Comment: 14 pages, 4 figure
Surprises in relativistic matter in a magnetic field
A short review of recent advances in understanding the dynamics of
relativistic matter in a magnetic field is presented. The emphasis is on the
dynamics related to the generation of the chiral shift parameter in the normal
ground state. We argue that the chiral shift parameter contributes to the axial
current density, but does not modify the conventional axial anomaly relation.
The analysis based on gauge invariant regularization schemes in the
Nambu-Jona-Lasinio model suggests that these findings should be valid also in
gauge theories. It is pointed out that the chiral shift parameter can affect
observable properties of compact stars and modify the key features of the
chiral magnetic effect in heavy ion collisions.Comment: 7 pages, 1 figure. V2: references added. Talk presented at Int.
School of Nuclear Physics "From Quarks and Gluons to Hadrons and Nuclei",
Erice-Sicily, 16 - 24 September, 201
Crossover from BCS to Composite Boson (Local Pair) Superconductivity in Quasi-2D systems
The crossover from cooperative Cooper pairing to independent bound state
(composite bosons) formation and condensation in quasi-2D systems is studied.
It is shown that at low carrier density the critical superconducting
temperature is equal to the temperature of Bose-condensation of ideal quasi-2D
Bose-gas with heavy dynamical mass, meanwhile at high densities the BCS result
remains valid. The evident nonmonotoneous behaviour of the critical temperature
as function of the coupling constant (the energy of the two particle bound
state) is a qualitative difference of quasi-2D crossover from 3D one.Comment: 9 pages, LaTeX, no figures. (The latest version which appeared in the
journal
Dynamical stabilization of runaway potentials at finite density
We study four dimensional non-abelian gauge theories with classical moduli.
Introducing a chemical potential for a flavor charge causes moduli to become
unstable and start condensing. We show that the moduli condensation in the
presence of a chemical potential generates nonabelian field strength
condensates. These condensates are homogeneous but non-isotropic. The end point
of the condensation process is a stable homogeneous, but non-isotropic, vacuum
in which both gauge and flavor symmetries and the rotational invariance are
spontaneously broken. Possible applications of this phenomenon for the gauge
theory/string theory correspondence and in cosmology are briefly discussed.Comment: revtex4, 4 pages; v.2: journal versio
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