13,700 research outputs found
Effective Transport Equations for non-Abelian Plasmas
Starting from classical transport theory, we derive a set of covariant
equations describing the dynamics of mean fields and their statistical
fluctuations in a non-Abelian plasma in or out of equilibrium. A general
procedure is detailed for integrating-out the fluctuations as to obtain the
effective transport equations for the mean fields. In this manner, collision
integrals for Boltzmann equations are obtained as correlators of fluctuations.
The formalism is applied to a hot non-Abelian plasma close to equilibrium. We
integrate-out explicitly the fluctuations with typical momenta of the Debye
mass, and obtain the collision integral in a leading logarithmic approximation.
We also identify a source for stochastic noise. The resulting dynamical
equations are of the Boltzmann-Langevin type. While our approach is based on
classical physics, we also give the necessary generalizations to study the
quantum plasmas. Ultimately, the dynamical equations for soft and ultra-soft
fields change only in the value for the Debye mass.Comment: 37 pages, revtex, no figures, section VII G modified, typos remove
Photon Self-Energy in a Color Superconductor
In a color superconductor the diquark condensates break spontaneously both
the color and ordinary electromagnetism, leaving a remanining rotated U(1)
symmetry unbroken. The gauge interactions associated to this rotated symmetry
may be considered as the in-medium electromagnetism. We compute the in-medium
photon self-energy in the presence of diquark condensates at high baryonic
density and weak coupling. This is done to one-loop order for the cases of two
and three quark flavors. For vanishing temperature, a detailed discussion is
given of the low momentum behavior of the photon polarization tensor. A simple
physical picture for the propagation of light in color superconducting media is
obtained. The main new effect is due to the diquark condensates, which lead to
a strong dielectric constant of the medium. The magnetic permeability remains
unchanged, because the primary condensates have vanishing spin and angular
momentum. In the two flavor case, an additional contribution arises due to
gapless quarks and electrons, which is responsible for Debye screening effects.
We also discuss the low energy effective theory for the three flavor case in
the presence of electromagnetic interactions.Comment: 26 pages, 4 postscript figures, appendix added, to appear in PR
Deriving effective transport equations for non-Abelian plasmas
Within classical transport theory, an approach is presented to derive
systematically effective collision terms and noise sources for effective
kinetic equations of non-Abelian plasmas. This procedure amounts to the
`integrating-out' of fluctuations, and is applicable for in- and
out-of-equilibrium situations. When applied to a hot non-Abelian plasma close
to equilibrium we recover the collision integral and the noise source first
obtained by B\"odeker. It is also shown that our approach, and hence
B\"odeker's effective theory, is consistent with the fluctuation-dissipation
theorem.Comment: 7 pages, needs sprocl.sty, invited talk given by DFL at 5th workshop
on QCD (QCD2000), Villefranche-sur-Mer, France, 3-7 Jan 200
Using Program Synthesis for Program Analysis
In this paper, we identify a fragment of second-order logic with restricted
quantification that is expressive enough to capture numerous static analysis
problems (e.g. safety proving, bug finding, termination and non-termination
proving, superoptimisation). We call this fragment the {\it synthesis
fragment}. Satisfiability of a formula in the synthesis fragment is decidable
over finite domains; specifically the decision problem is NEXPTIME-complete. If
a formula in this fragment is satisfiable, a solution consists of a satisfying
assignment from the second order variables to \emph{functions over finite
domains}. To concretely find these solutions, we synthesise \emph{programs}
that compute the functions. Our program synthesis algorithm is complete for
finite state programs, i.e. every \emph{function} over finite domains is
computed by some \emph{program} that we can synthesise. We can therefore use
our synthesiser as a decision procedure for the synthesis fragment of
second-order logic, which in turn allows us to use it as a powerful backend for
many program analysis tasks. To show the tractability of our approach, we
evaluate the program synthesiser on several static analysis problems.Comment: 19 pages, to appear in LPAR 2015. arXiv admin note: text overlap with
arXiv:1409.492
Representation and Encoding of Heterogeneous Data in a Web Based Research Environment for Manuscript and Textual Studies
This paper describes the general architecture of a digital research environment for manuscript and textual studies (particularly those pertaining to ancient Greek and Byzantine texts), and it discusses some questions of data representation and encoding in the framework of such an online research platform. The platform is being developed by the project Teuchos. Zentrum für Handschriften- und Textforschung, established in 2007 by the Institut für Griechische und Lateinische Philologie (Universität Hamburg) in cooperation with the Aristoteles-Archiv (Freie Universität Berlin). Teuchos is a long-term infrastructural project of the Universität Hamburg. It is currently in its three-year initial phase which is being co-funded by the German Research Foundation (DFG) through the "Thematic Information Networks" scheme within the "Scientific Library Services and Information Systems" programme. We introduce the main object types to be handled by our system and describe the overall functionality of the online platform. The paper focuses on the representations of two main object types: manuscripts as textual witnesses and watermarks, with an emphasis on the former. Since the adequate encoding of different layers of structure of a transmitted text is particularly relevant to optimising users' choices of navigating both digital images of the containing manuscripts and trancriptions of the text contained, this topic is discussed in some detail. We introduce the formal data model and the corresponding encoding for the object types discussed. The project encodes textual data in XML, aiming for TEI conformance where possible. Since no accepted XML model exists for the encoding of metadata within a watermark collection, we briefly explain how we chose to model the objects to accomodate the collections the project is making accessible
THE 5-D MODEL ANALYSIS OF BRD & BT FINANCIAL INSTITUTIONS IN TERMS OF THE CHARACTERS THAT APPEAR IN ADVERTISEMENTS
In times of difficult and unstable economic environment, market players try to differentiate themselves in order to survive and attract a large number of new customers. Financial institutions, as well as the full service segment, face a major obstacle, as in the negative power of intangibility ,that is reflected in the specific economic process. The “battle” for a place in front is increasingly fierce, and financial companies have begun to focus towards the removal of this drawback, and finding new communication techniques and actions, by assigning the company with some new values that will lead to greater confidence shown within consumers. In this article, we will try to underline two different tests of image association, as in the campaigns conducted by BRD - Groupe Societe Generale and Banca Transilvania, combining an endorsement campaign with a fairytale character, all of this processed through the filter of Romania’s set of cultural characteristics.cultural values, Hofstede, financial institutes, endorsement, image association
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