6,307 research outputs found
Topological Vertex, String Amplitudes and Spectral Functions of Hyperbolic Geometry
We discuss the homological aspects of the connection between quantum string
generating function and the formal power series associated to the dimensions of
chains and homologies of suitable Lie algebras. Our analysis can be considered
as a new straightforward application of the machinery of modular forms and
spectral functions (with values in the congruence subgroup of ) to the partition functions of Lagrangian branes, refined vertex and open
string partition functions, represented by means of formal power series that
encode Lie algebra properties. The common feature in our examples lies in the
modular properties of the characters of certain representations of the
pertinent affine Lie algebras and in the role of Selberg-type spectral
functions of an hyperbolic three-geometry associated with -series in the
computation of the string amplitudes.Comment: Revised version. References added, results remain unchanged. arXiv
admin note: text overlap with arXiv:hep-th/0701156, arXiv:1105.4571,
arXiv:1206.0664 by other author
Dual approaches for defects condensation
We review two methods used to approach the condensation of defects
phenomenon. Analyzing in details their structure, we show that in the limit
where the defects proliferate until occupy the whole space these two methods
are dual equivalent prescriptions to obtain an effective theory for the phase
where the defects (like monopoles or vortices) are completely condensed,
starting from the fundamental theory defined in the normal phase where the
defects are diluted.Comment: 7 pages, major modifications. Version accepted for publication in
Physics Letters
On the duality in four-dimensional Lorentz-breaking field theories
We consider new issues of duality in four-dimensional Lorentz-breaking field
theories. In particular, we demonstrate that the arising of the aether-like
Lorentz-breaking term is necessary in order for the 4D models to display the
duality analog between the MCS and self-dual models in 3D. We further study the
dispersion relations in both theories and discuss the physical contents of the
models involved in this new dualilty.Comment: 16 page
Massive photons and Dirac monopoles: electric condensate and magnetic confinement
We use the generalized Julia-Toulouse approach (GJTA) for condensation of
topological currents (charges or defects) to argue that massive photons can
coexist consistently with Dirac monopoles. The Proca theory is obtained here
via GJTA as a low energy effective theory describing an electric condensate and
the mass of the vector boson is responsible for generating a Meissner effect
which confines the magnetic defects in monopole-antimonopole pairs connected by
physical open magnetic vortices described by Dirac brane invariants, instead of
Dirac strings.Comment: 6 pages, version accepted for publication in Physics Letters
Dynamic RKKY interaction in graphene
The growing interest in carbon-based spintronics has stimulated a number of
recent theoretical studies on the RKKY interaction in graphene, based on which
the energetically favourable alignment between magnetic moments embedded in
this material can be calculated. The general consensus is that the strength of
the RKKY interaction in graphene decays as 1/D3 or faster, where D is the
separation between magnetic moments. Such an unusually fast decay for a
2-dimensional system suggests that the RKKY interaction may be too short ranged
to be experimentally observed in graphene. Here we show in a mathematically
transparent form that a far more long ranged interaction arises when the
magnetic moments are taken out of their equilibrium positions and set in
motion. We not only show that this dynamic version of the RKKY interaction in
graphene decays far more slowly but also propose how it can be observed with
currently available experimental methods.Comment: 7 pages, 2 figures, submitte
Scalar and Spinor Particles in the Spacetime of a Domain Wall in String Theory
We consider scalar and spinor particles in the spacetime of a domain wall in
the context of low energy effective string theories, such as the generalized
scalar-tensor gravity theories. This class of theories allows for an arbitrary
coupling of the wall and the (gravitational) scalar field. First, we derive the
metric of a wall in the weak-field approximation and we show that it depends on
the wall's surface energy density and on two post-Newtonian parameters. Then,
we solve the Klein-Gordon and the Dirac equations in this spacetime. We obtain
the spectrum of energy eigenvalues and the current density in the scalar and
spinor cases, respectively. We show that these quantities, except in the case
of the energy spectrum for a massless spinor particle, depend on the parameters
that characterize the scalar-tensor domain wall.Comment: LATEX file, 21 pages, revised version to appear in Phys. Rev.
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