872 research outputs found
The 1/N expansion of colored tensor models
In this paper we perform the 1/N expansion of the colored three dimensional
Boulatov tensor model. As in matrix models, we obtain a systematic topological
expansion, with more and more complicated topologies suppressed by higher and
higher powers of N. We compute the first orders of the expansion and prove that
only graphs corresponding to three spheres S^3 contribute to the leading order
in the large N limit.Comment: typos corrected, references update
Group field theories
Group field theories are particular quantum field theories defined on D
copies of a group which reproduce spin foam amplitudes on a space-time of
dimension D. In these lecture notes, we present the general construction of
group field theories, merging ideas from tensor models and loop quantum
gravity. This lecture is organized as follows. In the first section, we present
basic aspects of quantum field theory and matrix models. The second section is
devoted to general aspects of tensor models and group field theory and in the
last section we examine properties of the group field formulation of BF theory
and the EPRL model. We conclude with a few possible research topics, like the
construction of a continuum limit based on the double scaling limit or the
relation to loop quantum gravity through Schwinger-Dyson equationsComment: Lectures given at the "3rd Quantum Gravity and Quantum Geometry
School", march 2011, Zakopan
Renormalization of an Abelian Tensor Group Field Theory: Solution at Leading Order
We study a just renormalizable tensorial group field theory of rank six with
quartic melonic interactions and Abelian group U(1). We introduce the formalism
of the intermediate field, which allows a precise characterization of the
leading order Feynman graphs. We define the renormalization of the model,
compute its (perturbative) renormalization group flow and write its expansion
in terms of effective couplings. We then establish closed equations for the two
point and four point functions at leading (melonic) order. Using the effective
expansion and its uniform exponential bounds we prove that these equations
admit a unique solution at small renormalized coupling.Comment: 37 pages, 14 figure
Multiscale statistical process control with multiresolution data
An approach is presented for conducting multiscale statistical process control that adequately integrates data at different resolutions (multiresolution data), called MR-MSSPC. Its general structure is based on Bakshi's MSSPC framework designed to handle data at a single resolution. Significant modifications were introduced in order to process multiresolution information. The main MR-MSSPC features are presented and illustrated through three examples. Issues related to real world implementations and with the interpretation of the multiscale covariance structure are addressed in a fourth example, where a CSTR system under feedback control is simulated. Our approach proved to be able to provide a clearer definition of the regions where significant events occur and a more sensitive response when the process is brought back to normal operation, when it is compared with previous approaches based on single resolution data. © 2006 American Institute of Chemical Engineers AIChE J, 200
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