7,888 research outputs found
Wavelet Analysis of Inhomogeneous Data with Application to the Cosmic Velocity Field
In this article we give an account of a method of smoothing spatial
inhomogeneous data sets by using wavelet reconstruction on a regular grid in an
auxilliary space onto which the original data is mapped. In a previous paper by
the present authors, we devised a method for inferring the velocity potential
from the radial component of the cosmic velocity field assuming an ideal
sampling. Unfortunately the sparseness of the real data as well as errors of
measurement require us to first smooth the velocity field as observed on a
3-dimensional support (i.e. the galaxy positions) inhomogeneously distributed
throughout the sampled volume. The wavelet formalism permits us to introduce a
minimal smoothing procedure that is characterized by the variation in size of
the smothing window function. Moreover the output smoothed radial velocity
field can be shown to correspond to a well defined theoretical quantity as long
as the spatial sampling support satisfies certain criteria. We argue also that
one should be very cautious when comparing the velocity potential derived from
such a smoothed radial component of the velocity field with related quantities
derived from other studies (e.g : of the density field).Comment: 19 pages, Latex file, figures are avaible under requests, published
in Inverse Problems, 11 (1995) 76
Non-monotonic entanglement of physical EM field states in non-inertial frames
We develop a general technique to analyse the quantum effects of acceleration
on realistic spatially-localised electromagnetic field states entangled in the
polarization degree of freedom. We show that for this setting, quantum
entanglement may build up as the acceleration increases, providing a clear
signature of the quantum effects of relativistic acceleration.Comment: 5 pages, 3 figure
Deformed Superspace, N=1/2 Supersymmetry and (Non)Renormalization Theorems
We consider a deformed superspace in which the coordinates \theta do not
anticommute, but satisfy a Clifford algebra. We present results on the
properties of N=1/2 supersymmetric theories of chiral superfields in deformed
superspace, taking the Wess-Zumino model as the prototype. We prove new
(non)renormalization theorems: the F-term is radiatively corrected and becomes
indistinguishable from the D-term, while the Fbar-term is not renormalized.
Supersymmetric vacua are critical points of the antiholomorphic superpotential.
The vacuum energy is zero to all orders in perturbation theory. We illustrate
these results with several examples.Comment: 21 pages, 5 figures and one table; V2: references adde
Wave polarizations for a beam-like gravitational wave in quadratic curvature gravity
We compute analytically the tidal field and polarizations of an exact
gravitational wave generated by a cylindrical beam of null matter of finite
width and length in quadratic curvature gravity. We propose that this wave can
represent the gravitational wave that keep up with the high energy photons
produced in a gamma ray burst (GRB) source.Comment: 5 pages, 3 figures, minor corrections, to appear in CQ
Tools to integrate organoleptic quality criteria into breeding programs
This technical booklet provides methodologies and guidance to implement sensory evaluations for organoleptic quality assessment in multi-actor-projects for organic agriculture. It presents five detailed tests that can be used in sensory evaluation, methodologies on how to prepare the samples and a glossary. This booklet has been developed under Solibam project and updated during Diversifood project
Exact Results and Holography of Wilson Loops in N=2 Superconformal (Quiver) Gauge Theories
Using localization, matrix model and saddle-point techniques, we determine
exact behavior of circular Wilson loop in N=2 superconformal (quiver) gauge
theories. Focusing at planar and large `t Hooft couling limits, we compare its
asymptotic behavior with well-known exponential growth of Wilson loop in N=4
super Yang-Mills theory. For theory with gauge group SU(N) coupled to 2N
fundamental hypermultiplets, we find that Wilson loop exhibits non-exponential
growth -- at most, it can grow a power of `t Hooft coupling. For theory with
gauge group SU(N) x SU(N) and bifundamental hypermultiplets, there are two
Wilson loops associated with two gauge groups. We find Wilson loop in untwisted
sector grows exponentially large as in N=4 super Yang-Mills theory. We then
find Wilson loop in twisted sector exhibits non-analytic behavior with respect
to difference of two `t Hooft coupling constants. By letting one gauge coupling
constant hierarchically larger/smaller than the other, we show that Wilson
loops in the second type theory interpolate to Wilson loop in the first type
theory. We infer implications of these findings from holographic dual
description in terms of minimal surface of dual string worldsheet. We suggest
intuitive interpretation that in both type theories holographic dual background
must involve string scale geometry even at planar and large `t Hooft coupling
limit and that new results found in the gauge theory side are attributable to
worldsheet instantons and infinite resummation therein. Our interpretation also
indicate that holographic dual of these gauge theories is provided by certain
non-critical string theories.Comment: 52 pages, 7 figures v2. more figures embedded v3. minor stylistic
changes, v4. published versio
Collective Coordinates Theory for Discrete Soliton Ratchets in the sine-Gordon Model
A collective coordinate theory is develop for soliton ratchets in the damped
discrete sine-Gordon model driven by a biharmonic force. An ansatz with two
collective coordinates, namely the center and the width of the soliton, is
assumed as an approximated solution of the discrete non-linear equation. The
evolution of these two collective coordinates, obtained by means of the
Generalized Travelling Wave Method, explains the mechanism underlying the
soliton ratchet and captures qualitatively all the main features of this
phenomenon. The theory accounts for the existence of a non-zero depinning
threshold, the non-sinusoidal behaviour of the average velocity as a function
of the difference phase between the harmonics of the driver, the non-monotonic
dependence of the average velocity on the damping and the existence of
non-transporting regimes beyond the depinning threshold. In particular it
provides a good description of the intriguing and complex pattern of subspaces
corresponding to different dynamical regimes in parameter space
Emergent AdS3 and BTZ Black Hole from Weakly Interacting Hot 2d CFT
We investigate emergent holography of weakly coupled two-dimensional
hyperK\"ahler sigma model on cotangent bundle of (N-1)-dimensional complex
projective space at zero and finite temperature. The sigma model is motivated
by the spacetime conformal field theory dual to the near-horizon geometry of Q1
D1-brane bound to Q5 D5-brane wrapped on four-torus times circle, where N =
Q1*Q5. The sigma model admits nontrivial instanton for all N greater than or
equal to 2, which serves as a local probe of emergent holographic spacetime. We
define emergent geometry of the spacetime as that of instanton moduli space via
Hitchin's information metric. At zero temperature, we find that emergent
geometry is AdS3. At finite temperature, time-periodic instanton is mappable to
zero temperature instanton via conformal transformation. Utilizing the
transformation, we show that emergent geometry is precisely that of the
non-extremal, non-rotating BTZ black hole.Comment: 12 pages, no figure, JHEP.cls; v2. typos correcte
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