1,528 research outputs found
Three Dimensional Quantum Geometry and Deformed Poincare Symmetry
We study a three dimensional non-commutative space emerging in the context of
three dimensional Euclidean quantum gravity. Our starting point is the
assumption that the isometry group is deformed to the Drinfeld double D(SU(2)).
We generalize to the deformed case the construction of the flat Euclidean space
as the quotient of its isometry group ISU(2) by SU(2). We show that the algebra
of functions becomes the non-commutative algebra of SU(2) distributions endowed
with the convolution product. This construction gives the action of ISU(2) on
the algebra and allows the determination of plane waves and coordinate
functions. In particular, we show that: (i) plane waves have bounded momenta;
(ii) to a given momentum are associated several SU(2) elements leading to an
effective description of an element in the algebra in terms of several physical
scalar fields; (iii) their product leads to a deformed addition rule of momenta
consistent with the bound on the spectrum. We generalize to the non-commutative
setting the local action for a scalar field. Finally, we obtain, using harmonic
analysis, another useful description of the algebra as the direct sum of the
algebra of matrices. The algebra of matrices inherits the action of ISU(2):
rotations leave the order of the matrices invariant whereas translations change
the order in a way we explicitly determine.Comment: latex, 37 page
Schwarzian for colored Jackiw-Teitelboim gravity
We study the boundary effective action of the colored version of the
Jackiw-Teitelboim (JT) gravity. We derive the boundary action, which is the
color generalization of the Schwarzian action, from the BF
formulation of the colored JT gravity. Using different types of the
group decompositions both the zero and finite temperature cases are elaborated.
We provide the semi-classical perturbative analysis of the boundary action and
discuss the instability of the spin-1 mode and its implication for the quantum
chaos. A rainbow-AdS geometry is introduced where the color gauge symmetry
is spontaneously broken.Comment: 40 pages + appendi
Color decorations of Jackiw-Teitelboim gravity
We introduce the colored version of Jackiw-Teitelboim (JT) gravity which is
the two-dimensional dilaton gravity model with matrix-valued fields. It is
straightforwardly formulated in terms of BF action with gauge algebra
so that the standard JT gravity is embedded as
subsector. We also elaborate on the respective metric formulation which is
shown to involve the JT fields plus non-Abelian fields as well as
-matrix valued metric and dilaton fields. Their interactions are
governed by minimal couplings and potential terms of cubic and quartic orders
involving derivatives.Comment: 16 pages + appendi
ISO LWS Spectra of T Tauri and Herbig AeBe stars
We present an analysis of ISO-LWS spectra of eight T Tauri and Herbig AeBe young stellar objects.
Some of the objects are in the embedded phase of star-formation, whereas others have cleared their environs
but are still surrounded by a circumstellar disk. Fine-structure lines of [OI] and [CII] are most likely excited by
far-ultraviolet photons in the circumstellar environment rather than high-velocity outflows, based on comparisons
of observed line strengths with predictions of photon-dominated and shock chemistry models. A subset of our
stars and their ISO spectra are adequately explained by models constructed by Chiang & Goldreich (1997) and
Chiang et al. (2001) of isolated, passively heated, flared circumstellar disks. For these sources, the bulk of the
LWS flux at wavelengths longward of 55 µm arises from the disk interior which is heated diffusively by reprocessed
radiation from the disk surface. At 45 µm, water ice emission bands appear in spectra of two of the coolest stars,
and are thought to arise from icy grains irradiated by central starlight in optically thin disk surface layers
Dual Pair Correspondence in Physics: Oscillator Realizations and Representations
We study general aspects of the reductive dual pair correspondence, also known as Howe duality. We make an explicit and systematic treatment, where we first derive the oscillator realizations of all irreducible dual pairs: , , , , , and . Then, we decompose the Fock space into irreducible representations of each group in the dual pairs for the cases where one member of the pair is compact as well as the first non-trivial cases of where it is non-compact. We discuss the relevance of these representations in several physical applications throughout this analysis. In particular, we discuss peculiarities of their branching properties. Finally, closed-form expressions relating all Casimir operators of two groups in a pair are established
Colourful Poincaré symmetry, gravity and particle actions
We construct a generalisation of the three-dimensional Poincar\'e algebra that also includes a colour symmetry factor. This algebra can be used to define coloured Poincar\'e gravity in three space-time dimensions as well as to study generalisations of massive and massless free particle models. We present various such generalised particle models that differ in which orbits of the coloured Poincar\'e symmetry are described. Our approach can be seen as a stepping stone towards the description of particles interacting with a non-abelian background field or as a starting point for a worldline formulation of an associated quantum field theory
Qualification of a medium current ion implantation system in a semiconductor production environment
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 1996.Includes bibliographical references (p. 50-51).by Sandra K. Joung.M.S
Galaxies in box: A simulated view of the interstellar medium
We review progress in the development of physically realistic three
dimensional simulated models of the galaxy.We consider the scales from star
forming molecular clouds to the full spiral disc. Models are computed using
hydrodynamic (HD) or magnetohydrodynamic (MHD) equations and may include cosmic
ray or tracer particles. The range of dynamical scales between the full galaxy
structure and the turbulent scales of supernova (SN) explosions and even cloud
collapse to form stars, make it impossible with current computing tools and
resources to resolve all of these in one model. We therefore consider a
hierarchy of models and how they can be related to enhance our understanding of
the complete galaxy.Comment: Chapter in Large Scale Magnetic Fields in the Univers
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