125 research outputs found
Local electric current correlation function in an exponentially decaying magnetic field
The effect of an exponentially decaying magnetic field on the dynamics of
Dirac fermions in 3+1 dimensions is explored. The spatially decaying magnetic
field is assumed to be aligned in the third direction, and is defined by
{\mathbf{B}}(x)=B(x){\mathbf{e}}_{z}, with B(x)=B_{0}e^{-\xi\ x/\ell_{B}}.
Here, \xi\ is a dimensionless damping factor and \ell_{B}=(eB_{0})^{-1/2} is
the magnetic length. As it turns out, the energy spectrum of fermions in this
inhomogeneous magnetic field can be analytically determined using the Ritus
method. Assuming the magnetic field to be strong, the chiral condensate and the
\textit{local} electric current correlation function are computed in the lowest
Landau level (LLL) approximation and the results are compared with those
arising from a strong homogeneous magnetic field. Although the constant
magnetic field B_{0} can be reproduced by taking the limit of \xi-> 0 and/or
x-> 0 from B(x), these limits turn out to be singular once the quantum
corrections are taken into account.Comment: V1: 16 pages, 7 figures, 2 tables; V2: Section II improved,
references added. Version accepted for publication in PR
Gravitational catalysis of chiral and color symmetry breaking of quark matter in hyperbolic space
We study the dynamical breaking of chiral and color symmetries of dense quark
matter in the ultrastatic hyperbolic spacetime in the framework
of an extended Nambu--Jona-Lasinio model. On the basis of analytical
expressions for chiral and color condensates as functions of curvature and
temperature, the phenomenon of dimensional reduction and gravitational
catalysis of symmetry breaking in strong gravitational field is demonstrated in
the regime of weak coupling constants. In the case of strong couplings it is
shown that curvature leads to small corrections to the flat-space values of
condensate and thus enhances the symmetry breaking effects. Finally, using
numerical calculations phase transitions under the influence of chemical
potential and negative curvature are considered and the phase portrait of the
system is constructed.Comment: 14 pages, 5 figure
Chiral dynamics in QED and QCD in a magnetic background and nonlocal noncommutative field theories
We study the connection of the chiral dynamics in QED and QCD in a strong
magnetic field with noncommutative field theories (NCFT). It is shown that
these dynamics determine complicated nonlocal NCFT. In particular, although the
interaction vertices for electrically neutral composites in these gauge models
can be represented in the space with noncommutative spatial coordinates, there
is no field transformation that could put the vertices in the conventional form
considered in the literature. It is unlike the Nambu-Jona-Lasinio (NJL) model
in a magnetic field where such a field transformation can be found, with a cost
of introducing an exponentially damping form factor in field propagators. The
crucial distinction between these two types of models is in the characters of
their interactions, being short-range in the NJL-like models and long-range in
gauge theories. The relevance of the NCFT connected with the gauge models for
the description of the quantum Hall effect in condensed matter systems with
long-range interactions is briefly discussed.Comment: 19 pages, REVTeX4, v2: clarifications added, v3: to match PRD versio
Color superconductivity in the static Einstein Universe
We study the behavior of quark and diquark condensates in dense quark matter
under the influence of a gravitational field adopting as a simple model the
static dimensional Einstein Universe. Calculations are performed in the
framework of the extended Nambu--Jona-Lasinio model at finite temperature and
quark density on the basis of the thermodynamic potential and the gap
equations. Quark and diquark condensates as functions of the chemical potential
and temperature at different values of the curvature have been studied. Phase
portraits of the system have been constructed
Phase diagram of hot magnetized two-flavor color superconducting quark matter
A two-flavor color superconducting (2SC) Nambu--Jona-Lasinio (NJL) model is
introduced at finite temperature T, chemical potential mu and in the presence
of a constant magnetic field eB. The effect of (T,mu,eB) on the formation of
chiral and color symmetry breaking condensates is studied. The complete phase
portrait of the model in T-mu, mu-eB, and T-eB phase spaces for various fixed
eB, T, and mu is explored. A threshold magnetic field eB_t~ 0.5 GeV^2 is found
above which the dynamics of the system is solely dominated by the lowest Landau
level (LLL) and the effects of T and mu are partly compensated by eB.Comment: V1: 29 pages, 15 figures, 3 tables. V2: Discussions improved. Version
accepted for publication in PR
Plasmonic nanoparticle monomers and dimers: From nano-antennas to chiral metamaterials
We review the basic physics behind light interaction with plasmonic
nanoparticles. The theoretical foundations of light scattering on one metallic
particle (a plasmonic monomer) and two interacting particles (a plasmonic
dimer) are systematically investigated. Expressions for effective particle
susceptibility (polarizability) are derived, and applications of these results
to plasmonic nanoantennas are outlined. In the long-wavelength limit, the
effective macroscopic parameters of an array of plasmonic dimers are
calculated. These parameters are attributable to an effective medium
corresponding to a dilute arrangement of nanoparticles, i.e., a metamaterial
where plasmonic monomers or dimers have the function of "meta-atoms". It is
shown that planar dimers consisting of rod-like particles generally possess
elliptical dichroism and function as atoms for planar chiral metamaterials. The
fabricational simplicity of the proposed rod-dimer geometry can be used in the
design of more cost-effective chiral metamaterials in the optical domain.Comment: submitted to Appl. Phys.
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