5,917 research outputs found
Quasiconformality and mass
We identify universal quasiconformal (walking) behaviour in non-Abelian gauge
field theories based on the mass-dependent all-order beta-function introduced
in arXiv:0908.1364. We find different types of walking behaviour in the
presence of (partially) massive species. We employ our findings to the
construction of candidate theories for dynamical electroweak symmetry breaking
by walking technicolour.Comment: 16 pages, 8 figures
SELF-DUAL SUPERGRAVITIES
The N-extended supersymmetric self-dual Poincar\'e supergravity equations
provide a natural local description of supermanifolds possessing hyperk\"ahler
structure. These equations admit an economical formulation in chiral
superspace. A reformulation in harmonic superspace encodes self-dual
supervielbeins and superconnections in a graded skew-symmetric supermatrix
superfield prepotential satisfying generalised Cauchy-Riemann conditions. A
recipe is presented for extracting explicit self-dual supervielbeins and
superconnections from such `analytic' prepotentials. We demonstrate the method
by explicitly decoding a simple example of superfield prepotential, analogous
to that corresponding to the Taub-NUT solution. The superspace we thus
construct is an interesting supersymmetric deformation of flat space,
having flat `body' and constant curvature `soul'.Comment: 14 pages, latex fil
A Characteristic Planetary Feature in Double-Peaked, High-Magnification Microlensing Events
A significant fraction of microlensing planets have been discovered in
high-magnification events, and a significant fraction of these events exhibit a
double-peak structure at their peak. However, very wide or very close binaries
can also produce double-peaked high-magnification events, with the same gross
properties as those produced by planets. Traditionally, distinguishing between
these two interpretations has relied upon detailed modeling, which is both
time-consuming and generally does not provide insight into the observable
properties that allow discrimination between these two classes of models. We
study the morphologies of these two classes of double-peaked high-magnification
events, and identify a simple diagnostic that can be used to immediately
distinguish between perturbations caused by planetary and binary companions,
without detailed modeling. This diagnostic is based on the difference in the
shape of the intra-peak region of the light curves. The shape is smooth and
concave for binary lensing, while it tends to be either boxy or convex for
planetary lensing. In planetary lensing this intra-peak morphology is due to
the small, weak cusp of the planetary central caustic located between the two
stronger cusps. We apply this diagnostic to five observed double-peaked
high-magnification events to infer their underlying nature. A corollary of our
study is that good coverage of the intra-peak region of double-peaked
high-magnification events is likely to be important for their unique
interpretation.Comment: 6 pages, 3 figure
Low-Energy Effective Action in Non-Perturbative Electrodynamics in Curved Spacetime
We study the heat kernel for the Laplace type partial differential operator
acting on smooth sections of a complex spin-tensor bundle over a generic
-dimensional Riemannian manifold. Assuming that the curvature of the U(1)
connection (that we call the electromagnetic field) is constant we compute the
first two coefficients of the non-perturbative asymptotic expansion of the heat
kernel which are of zero and the first order in Riemannian curvature and of
arbitrary order in the electromagnetic field. We apply these results to the
study of the effective action in non-perturbative electrodynamics in four
dimensions and derive a generalization of the Schwinger's result for the
creation of scalar and spinor particles in electromagnetic field induced by the
gravitational field. We discover a new infrared divergence in the imaginary
part of the effective action due to the gravitational corrections, which seems
to be a new physical effect.Comment: LaTeX, 42 page
New data on the distribution of Cossidae (Lepidoptera) in Mongolia
We recorded a new species of Cossidae – Acossus terebrus (Denis & Schiffermüller, 1776) – for Mongolia (Tov Aimak). We also report on the most northern habitat of the cossid genus Gobibatyr Yakovlev, 2004 (North-West Mongolia, Bayan-Ulegej Aimak), which shows the permeability of the Mongolian Altai Mountain Range for some elements of the Dzungarian fauna. Additionally, our sampling resulted in adding new localities to the ranges of Catopta perunovi Yakovlev, 2007 and Cecryphallus nubila (Staudinger, 1895) (first discovered in Hovd Aimak)
Proper Dirac Quantization of Free Particle on D-Dimensional Sphere
We show that an unambiguous and correct quantization of the second-class
constrained system of a free particle on a sphere in dimensions is possible
only by converting the constraints to abelian gauge constraints, which are of
first class in Dirac's classification scheme. The energy spectrum is equal to
that of a pure Laplace-Beltrami operator with no additional constant arising
from the curvature of the sphere. A quantization of Dirac's modified Poisson
brackets for second-class constraints is also possible and unique, but must be
rejected since the resulting energy spectrum is physically incorrect.Comment: Author Information under
http://www.physik.fu-berlin.de/~kleinert/institution.html Paper also at
http://www.physik.fu-berlin.de/~kleinert/kleiner_re253/preprint.htm
Silicon nanoparticles and interstellar extinction
To examine a recently proposed hypothesis that silicon nanoparticles are the
source of extended red emission (ERE) in the interstellar medium, we performed
a detailed modeling of the mean Galactic extinction in the presence of silicon
nanoparticles. For this goal we used the appropriate optical constants of
nanosized Si, essentially different from those of bulk Si due to quantum
confinement. It was found that a dust mixture of silicon nanoparticles, bare
graphite grains, silicate core-organic refractory mantle grains and three-layer
silicate-water ice-organic refractory grains works well in explaining the
extinction and, in addition, results in the acceptable fractions of UV/visible
photons absorbed by silicon nanoparticles: 0.071-0.081. Since these fractions
barely agree with the fraction of UV/visible photons needed to excite the
observed ERE, we conclude that the intrinsic photon conversion efficiency of
the photoluminescence by silicon nanoparticles must be near 100%, if they are
the source of the ERE.Comment: Latex2e, uses emulateapj.sty (included), multicol.sty, epsf.sty, 6
pages, 3 figures (8 Postscript files), accepted for publication in ApJ
Letters, complete Postscript file is also available at
http://physics.technion.ac.il/~zubko/eb.html#SNP
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