7,015 research outputs found
Is Strong Gravitational Radiation predicted by TeV-Gravity?
In TeV-gravity models the gravitational coupling to particles with energies
E\sim m_{Pl} \sim 10 TeV is not suppressed by powers of ultra-small ratio
E/M_{Pl} with M_{Pl} \sim 10^{19} GeV. Therefore one could imagine strong
synchrotron radiation of gravitons by the accelerating particles to become the
most pronounced manifestation of TeV-gravity at LHC. However, this turns out to
be not true: considerable damping continues to exist, only the place of
E/M_{Pl} it taken by a power of a ratio \theta\omega/E, where the typical
frequency \omega of emitted radiation, while increased by a number of
\gamma-factors, can not reach E/\vartheta unless particles are accelerated by
nearly critical fields. Moreover, for currently available magnetic fields B
\sim 10 Tesla, multi-dimensionality does not enhance gravitational radiation at
all even if TeV-gravity is correct.Comment: 7 pages, LaTe
Horizontal-Branch Models and the Second-Parameter Effect. IV. The Case of M3 and Palomar 3
We present a detailed analysis of the "second-parameter pair" of globular
clusters M3 (NGC 5272) and Palomar 3. Our main results can be summarized as
follows: i) The horizontal-branch (HB) morphology of M3 is significantly bluer
in its inner regions (observed with the Hubble Space Telescope) than in the
cluster outskirts (observed from the ground), i.e., M3 has an internal second
parameter. Most plausibly the mass loss on the red giant branch (RGB) has been
more efficient in the inner than in the outer regions of the cluster. ii) The
dispersion in mass of the Pal 3 HB is found to be very small -- consistent with
zero -- and we argue that this is unlikely to be due to a statistical
fluctuation. It is this small mass dispersion that leads to the most apparent
difference in the HB morphologies of M3 and Pal 3. iii) The relative HB types
of M3 and Pal 3, as measured by mean colors or parameters involving the number
of blue, variable, and red HB stars, can easily be accounted for by a fairly
small difference in age between these clusters, of order 0.5-1 Gyr -- which is
in good agreement with the relative age measurement, based on the clusters'
turnoffs, by VandenBerg (2000).Comment: 20 pages, 12 figures, emulateapj5 style. The Astrophysical Journal,
in press. Figs. 1, 6, 9, 10 are in png format. The preprint (postscript
format) with full resolution (embedded) figures is available from
http://www.astro.virginia.edu/~mc6v
Parafermionic Liouville field theory and instantons on ALE spaces
In this paper we study the correspondence between the
coset conformal field
theories and SU(n) gauge theories on
. Namely we check the correspondence between the
SU(2) Nekrasov partition function on and the
conformal blocks of the parafermion algebra (in and modules).
We find that they are equal up to the U(1)-factor as it was in all cases of
AGT-like relations. Studying the structure of the instanton partition function
on we also find some evidence that this
correspondence with arbitrary takes place up to the U(1)-factor.Comment: 21 pages, 6 figures, misprints corrected, references added, version
to appear in JHE
Resolvents and Seiberg-Witten representation for Gaussian beta-ensemble
The exact free energy of matrix model always obeys the Seiberg-Witten (SW)
equations on a complex curve defined by singularities of the quasiclassical
resolvent. The role of SW differential is played by the exact one-point
resolvent. We show that these properties are preserved in generalization of
matrix models to beta-ensembles. However, since the integrability and
Harer-Zagier topological recursion are still unavailable for beta-ensembles, we
need to rely upon the ordinary AMM/EO recursion to evaluate the first terms of
the genus expansion. Consideration in this paper is restricted to the Gaussian
model.Comment: 15 page
Intersections of quadrics, moment-angle manifolds, and Hamiltonian-minimal Lagrangian embeddings
We study the topology of Hamiltonian-minimal Lagrangian submanifolds N in C^m
constructed from intersections of real quadrics in a work of the first author.
This construction is linked via an embedding criterion to the well-known
Delzant construction of Hamiltonian toric manifolds. We establish the following
topological properties of N: every N embeds as a submanifold in the
corresponding moment-angle manifold Z, and every N is the total space of two
different fibrations, one over the torus T^{m-n} with fibre a real moment-angle
manifold R, and another over a quotient of R by a finite group with fibre a
torus. These properties are used to produce new examples of Hamiltonian-minimal
Lagrangian submanifolds with quite complicated topology.Comment: 14 pages, published version (minor changes
Brezin-Gross-Witten model as "pure gauge" limit of Selberg integrals
The AGT relation identifies the Nekrasov functions for various N=2 SUSY gauge
theories with the 2d conformal blocks, which possess explicit Dotsenko-Fateev
matrix model (beta-ensemble) representations the latter being polylinear
combinations of Selberg integrals. The "pure gauge" limit of these matrix
models is, however, a non-trivial multiscaling large-N limit, which requires a
separate investigation. We show that in this pure gauge limit the Selberg
integrals turn into averages in a Brezin-Gross-Witten (BGW) model. Thus, the
Nekrasov function for pure SU(2) theory acquires a form very much reminiscent
of the AMM decomposition formula for some model X into a pair of the BGW
models. At the same time, X, which still has to be found, is the pure gauge
limit of the elliptic Selberg integral. Presumably, it is again a BGW model,
only in the Dijkgraaf-Vafa double cut phase.Comment: 21 page
Generalized matrix models and AGT correspondence at all genera
We study generalized matrix models corresponding to n-point Virasoro
conformal blocks on Riemann surfaces with arbitrary genus g. Upon AGT
correspondence, these describe four dimensional N=2 SU(2)^{n+3g-3} gauge
theories with generalized quiver diagrams. We obtain the generalized matrix
models from the perturbative evaluation of the Liouville correlation functions
and verify the consistency of the description with respect to degenerations of
the Riemann surface. Moreover, we derive the Seiberg-Witten curve for the N=2
gauge theory as the spectral curve of the generalized matrix model, thus
providing a check of AGT correspondence at all genera.Comment: 19 pages; v2: version to appear in JHE
Mechanisms of arsenic clustering in silicon
A model of arsenic clustering in silicon is proposed and analyzed. The main
feature of the proposed model is the assumption that negatively charged arsenic
complexes play a dominant role in the clustering process. To confirm this
assumption, electron density and concentration of impurity atoms incorporated
into the clusters are calculated as functions of the total arsenic
concentration. A number of the negatively charged clusters incorporating a
point defect and one or more arsenic atoms are investigated. It is shown that
for the doubly negatively charged clusters or for clusters incorporating more
than one arsenic atom the electron density reaches a maximum value and then
monotonically and slowly decreases as total arsenic concentration increases. In
the case of doubly negatively charged cluster incorporating two arsenic atoms,
the calculated electron density agrees well with the experimental data.
Agreement with the experiment confirms the conclusion that two arsenic atoms
participate in the cluster formation. Among all present models, the proposed
model of clustering by formation of doubly negatively charged cluster
incorporating two arsenic atoms gives the best fit to the experimental data and
can be used in simulation of high concentration arsenic diffusion.Comment: 13 pages, 4 figures. Revised and shortened version of the paper has
been published in Phys. Rev. B, Vol.74 (3), art. no. 035205 (2006
Genus-one correction to asymptotically free Seiberg-Witten prepotential from Dijkgraaf-Vafa matrix model
We find perfect agreements on the genus-one correction to the prepotential of
SU(2) Seiberg-Witten theory with N_f=2, 3 between field theoretical and
Dijkgraaf-Vafa-Penner type matrix model results.Comment: 12 pages; v2: minor revision; v3: more structured, submitted versio
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