9,643 research outputs found
Generalized q-deformed Correlation Functions as Spectral Functions of Hyperbolic Geometry
We analyse the role of vertex operator algebra and 2d amplitudes from the
point of view of the representation theory of infinite dimensional Lie
algebras, MacMahon and Ruelle functions. A p-dimensional MacMahon function is
the generating function of p-dimensional partitions of integers. These
functions can be represented as amplitudes of a two-dimensional c=1 CFT. In
this paper we show that p-dimensional MacMahon functions can be rewritten in
terms of Ruelle spectral functions, whose spectrum is encoded in the
Patterson-Selberg function of three dimensional hyperbolic geometry.Comment: 12 pages, no figure
Euclidean thermal spinor Green's function in the spacetime of a straight cosmic string
Within the framework of the quantum field theory at finite temperature on a
conical space, we determine the Euclidean thermal spinor Green's function for a
massless spinor field. We then calculate the thermal average of the
energy-momentum tensor of a thermal bath of massless fermions. In the
high-temperature limit, we find that the straight cosmic string does not
perturb the thermal bathComment: 11 pages, latex, no figure
Graphene-based spin-pumping transistor
We demonstrate with a fully quantum-mechanical approach that graphene can
function as gate-controllable transistors for pumped spin currents, i.e., a
stream of angular momentum induced by the precession of adjacent
magnetizations, which exists in the absence of net charge currents.
Furthermore, we propose as a proof of concept how these spin currents can be
modulated by an electrostatic gate. Because our proposal involves nano-sized
systems that function with very high speeds and in the absence of any applied
bias, it is potentially useful for the development of transistors capable of
combining large processing speeds, enhanced integration and extremely low power
consumption
Graphene as a non-magnetic spin-current lens
In spintronics, the ability to transport magnetic information often depends
on the existence of a spin current traveling between two different magnetic
objects acting as source and probe. A large fraction of this information never
reaches the probe and is lost because the spin current tends to travel
omni-directionally. We propose that a curved boundary between a gated and a
non-gated region within graphene acts as an ideal lens for spin currents
despite being entirely of non-magnetic nature. We show as a proof of concept
that such lenses can be utilized to redirect the spin current that travels away
from a source onto a focus region where a magnetic probe is located, saving a
considerable fraction of the magnetic information that would be otherwise lost.Comment: 9 pages, 3 figure
Transparent Replication Using Metaprogramming in Cyan
Replication can be used to increase the availability of a service by creating
many operational copies of its data called replicas. Active replication is a
form of replication that has strong consistency semantics, easier to reason
about and program. However, creating replicated services using active
replication still demands from the programmer the knowledge of subtleties of
the replication mechanism. In this paper we show how to use the metaprogramming
infrastructure of the Cyan language to shield the application programmer from
these details, allowing easier creation of fault-tolerant replicated
applications through simple annotations.Comment: 8 page
Operator Product on Locally Symmetric Spaces of Rank One and the Multiplicative Anomaly
The global multiplicative properties of Laplace type operators acting on
irreducible rank one symmetric spaces are considered. The explicit form of the
multiplicative anomaly is derived and its corresponding value is calculated
exactly, for important classes of locally symmetric spaces and different
dimensions.Comment: Int. Journal of Modern Physics A, vol. 18 (2003), 2179-218
Contributions from Dilatonic Strings to the Flat Behaviour of the Rotational Curves in Galaxies
We analyse the flat behaviour of the rotational curves in some galaxies in
the framework of a dilatonic, current-carrying string. We determine the
expression of the tangential velocity of test objects following a stable
circular equatorial orbit in this spacetime.Comment: This version to be published in the Int. Journal of Modern Phys.
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