7,793 research outputs found
On the Hagedorn Behaviour of Singular Scale-Invariant Plane Waves
As a step towards understanding the properties of string theory in
time-dependent and singular spacetimes, we study the divergence of density
operators for string ensembles in singular scale-invariant plane waves, i.e.
those plane waves that arise as the Penrose limits of generic power-law
spacetime singularities. We show that the scale invariance implies that the
Hagedorn behaviour of bosonic and supersymmetric strings in these backgrounds,
even with the inclusion of RR or NS fields, is the same as that of strings in
flat space. This is in marked contrast to the behaviour of strings in the BFHP
plane wave which exhibit quantitatively and qualitatively different
thermodynamic properties.Comment: 15 pages, LaTeX2e, v2: JHEP3.cls, one reference adde
Available Dispute Resolution Processes Within the Reauthorized Individuals with Disabilities Education Improvement Act (IDEIA) of 2004: Where Do Mediation Principles Fit In?
The Individual Disabilities Education Act of 1997 first offered mediation processes to parents and school systems as an available dispute resolution process. Congress mandated that mediation be made available whenever a due process hearing was filed. The intent was to assist parents and school systems in resolving their differences regarding the educational needs for children with disabilities through increased discussions and collaborative efforts; this would reduce the need for costly and adversarial litigation. Alternative dispute resolution processes have taken an increasingly dominant role within the newly reauthorized IDEIA of 2004, reflecting Congressional promotion of parent and district collaboration for achieving the Act\u27s goals
PP-Wave / CFT_2 Duality
We investigate the pp-wave limit of the AdS_3\times S^3\times K3
compactification of Type IIB string theory from the point of view of the dual
Sym_N(K3) CFT. It is proposed that a fundamental string in this pp-wave
geometry is dual to the c=6 effective string of the Sym_N(K3) CFT, with the
string bits of the latter being composed of twist operators. The massive
fundamental string oscillators correspond to certain twisted Virasoro
generators in the effective string. It is shown that both the ground states and
the genus expansion parameter (at least in the orbifold limit of the CFT)
coincide. Surprisingly the latter scales like J^2/N rather than the J^4/N^2
which might have been expected. We demonstrate a leading-order agreement
between the pp-wave and CFT particle spectra. For a degenerate special case
(one NS 5-brane) an intriguing complete agreement is found.Comment: JHEP3 LaTeX, 20 pages; discussion of WZW levels clarified, reference
adde
Localization and Diagonalization: A review of functional integral techniques for low-dimensional gauge theories and topological field theories
We review localization techniques for functional integrals which have
recently been used to perform calculations in and gain insight into the
structure of certain topological field theories and low-dimensional gauge
theories. These are the functional integral counterparts of the Mathai-Quillen
formalism, the Duistermaat-Heckman theorem, and the Weyl integral formula
respectively. In each case, we first introduce the necessary mathematical
background (Euler classes of vector bundles, equivariant cohomology, topology
of Lie groups), and describe the finite dimensional integration formulae. We
then discuss some applications to path integrals and give an overview of the
relevant literature. The applications we deal with include supersymmetric
quantum mechanics, cohomological field theories, phase space path integrals,
and two-dimensional Yang-Mills theory.Comment: 72 pages (60 A4 pages), LaTeX (to appear in the Journal of
Mathematical Physics Special Issue on Functional Integration (May 1995)
Residues and Topological Yang-Mills Theory in Two Dimensions
A residue formula which evaluates any correlation function of topological
Yang-Mills theory with arbitrary magnetic flux insertion in two
dimensions are obtained. Deformations of the system by two form operators are
investigated in some detail. The method of the diagonalization of a matrix
valued field turns out to be useful to compute various physical quantities. As
an application we find the operator that contracts a handle of a Riemann
surface and a genus recursion relation.Comment: 23 pages, some references added, to appear in Rev.Math.Phy
Strings on pp-waves and Hadrons in (softly broken) N=1 gauge theories
We study the Penrose limit of Type IIB duals of softly broken N=1 SU(N) gauge
theories in four dimensions, obtained as deformations of the Maldacena-Nunez
and Klebanov-Strassler backgrounds. We extract the string spectrum on the
resulting pp-wave backgrounds and discuss some properties of the conjectured
dual gauge theory hadrons, the so called "Annulons". The string zero-point
energy on the light-cone is nontrivial, due to the loss of linearly realized
worldsheet supersymmetry, and negative, even in the unbroken supersymmetric
case. This causes the appearance of non-perturbative corrections to the
hadronic mass spectrum. We briefly discuss the thermodynamic behavior of these
string models, calculating the corresponding Hagedorn temperatures.Comment: 20 page
M-theory on a Time-dependent Plane-wave
We propose a matrix model on a homogeneous plane-wave background with 20
supersymmetries. This background is anti-Mach type and is equivalent to the
time-dependent background. We study supersymmetries in this theory and
calculate the superalgebra. The vacuum energy of the abelian part is also
calculated. In addition we find classical solutions such as graviton solution,
fuzzy sphere and hyperboloid.Comment: 19pages, no figures, LaTeX, JHEP3.cl
The Unbearable Beingness of Light, Dressing and Undressing Photons in Black Hole Spacetimes
Gravitational tidal forces acting on the virtual e+ e- cloud surrounding a
photon endow spacetime with a non-trivial refractive index. This has remarkable
properties unique to gravitational theories including superluminal
low-frequency propagation, in apparent violation of causality, and
amplification of the renormalized photon field, in apparent violation of
unitarity. Using the geometry of null congruences and the Penrose limit, we
illustrate these phenomena and their resolution by tracing the history of a
photon as it falls into the near-singularity region of a black hole.Comment: 8 pages, Essay awarded third prize in the Gravity Research Foundation
essay competition 201
On symmetries of Chern-Simons and BF topological theories
We describe constructing solutions of the field equations of Chern-Simons and
topological BF theories in terms of deformation theory of locally constant
(flat) bundles. Maps of flat connections into one another (dressing
transformations) are considered. A method of calculating (nonlocal) dressing
symmetries in Chern-Simons and topological BF theories is formulated
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