Oblique DLCQ M-theory and Multiple M2-branes

We propose an oblique DLCQ as a limit to realize a theory of multiple M2-branes in M(atrix)-theory context. The limit is a combination of an infinite boosting of a space-like circle and a tuned tilting of the circle direction. We obtain a series of supergravity solutions describing various dual configurations including multiple M2-branes. For an infinite boosting along a circle wrapped obliquely around a rectangular torus, Seiberg's DLCQ limit distorts the torus modulus. In the context of supergravity, we show explicitly how this torus modulus of $\widetilde{\text M}$-theory is realized as the vacuum modulus of dual IIB-theory.Comment: v3: 25pages, extended version, References adde

Planck-scale relativity from quantum κ\kappa-Poincar\'e algebra

Extending the commutator algebra of quantum $\kappa$-Poincar\'e symmetry to the whole of the phase space, and assuming that this algebra is to be covariant under action of deformed Lorentz generators, we derive the transformation properties of positions under the action of deformed boosts. It turns out that these transformations leave invariant the quadratic form in the position space, which is the Minkowski metric and that the boosts saturate. The issues of massless and massive particles motion, as well as time dilatation and length contraction in this new framework are also studied.Comment: 14 pages, LaTeX, no figure

Cosmology at the boundary of de Sitter using the dS/QFT correspondence

Using the dS/QFT correspondence in the context of inflation allows for the study of interesting, otherwise inaccessible physics. In particular, by studying inflation via its dual field theory at the boundary of the de Sitter space, it may be possible to study a regime of strongly coupled gravity at early times. The purpose of this work is to completely express cosmological observables in terms of the free parameters of a dual field theory and to compare them with CMB data. In this way, constraints on the observational parameters constrains the validity of the strongly coupled inflation picture by imposing limits on the parameters of the field theory. The fit with data defines a limit for the consistency and validity of the approach taken and shows that, within this limit, the model is almost unconstrained, but quite predictive, producing power spectra of density perturbations extremely near scale invariance

How Bob Laughlin Tamed the Giant Graviton from Taub-NUT space

In this paper we show how two dimensional electron systems can be modeled by strings interacting with D-branes. The dualities of string theory allow several descriptions of the system. These include descriptions in terms of solitons in the near horizon D6-brane theory, non-commutative gauge theory on a D2-brane, the Matrix Theory of D0-branes and finally as a giant graviton in M-theory. The soliton can be described as a D2-brane with an incompressible fluid of D0-branes and charged string-ends moving on it. Including an NS5 brane in the system allows for the existence of an edge with the characteristic massless chiral edge states of the Quantum Hall system.Comment: 26 pages, 4 figures, discussions adde

The GLAS physical inversion method for analysis of HIRS2/MSU sounding data

Goddard Laboratory for Atmospheric Sciences has developed a method to derive atmospheric temperature profiles, sea or land surface temperatures, sea ice extent and snow cover, and cloud heights and fractional cloud, from HIRS2/MSU radiance data. Chapter 1 describes the physics used in the radiative transfer calculations and demonstrates the accuracy of the calculations. Chapter 2 describes the rapid transmittance algorithm used and demonstrates its accuracy. Chapter 3 describes the theory and application of the techniques used to analyze the satellite data. Chapter 4 shows results obtained for January 1979

Low-energy scattering of extremal black holes by neutral matter

We investigate the decay of a spherically symmetric near-extremal charged black hole, including back-reaction effects, in the near-horizon region. The non-locality of the effective action controlling this process allows and also forces us to introduce a complementary set of boundary conditions which permit to determine the asymptotic late time Hawking flux. The evaporation rate goes down exponentially and admits an infinite series expansion in Planck's constant. At leading order it is proportional to the total mass and the higher order terms involve higher order momenta of the classical stress-tensor. Moreover we use this late time behaviour to go beyond the near-horizon approximation and comment on the implications for the information loss paradox.Comment: LaTeX file, 14 pages. Expanded version replacing earlier hep-th/001201

The Number of States of Two Dimensional Critical String Theory

We discuss string theory vacua which have the wrong number of spacetime dimensions, and give a crude argument that vacua with more than four large dimensions are improbable. We then turn to two dimensional vacua, which naively appear to violate Bekenstein's entropy principle. A classical analysis shows that the naive perturbative counting of states is unjustified. All excited states of the system have strong coupling singularities which prevent us from concluding that they really exist. A speculative interpretation of the classical solutions suggests only a finite number of states will be found in regions bounded by a finite area. We also argue that the vacuum degeneracy of two dimensional classical string theory is removed in quantum mechanics. The system appears to be in a Kosterlitz-Thouless phase. This leads to the conclusion that it is also improbable to have only two large spacetime dimensions in string theory. However, we note that, unlike our argument for high dimensions, our conclusions about the ground state have neglected two dimensional quantum gravitational effects, and are at best incomplete.Comment: 12 pages, harvma

On a Matrix Model of Level Structure

We generalize the dimensionally reduced Yang-Mills matrix model by adding d=1 Chern-Simons term and terms for a bosonic vector. The coefficient, \kappa of the Chern-Simons term must be integer, and hence the level structure. We show at the bottom of the Yang-Mills potential, the low energy limit, only the linear motion is allowed for D0 particles. Namely all the particles align themselves on a single straight line subject to \kappa^2/r^2 repulsive potential from each other. We argue the relevant brane configuration to be D0-branes in a D4 after \kappa of D8's pass the system.Comment: 1+6 pages, No figure, LaTeX; Minor changes; To appear in Class. Quant. Gra