30,707 research outputs found
Critical Behaviour of the Fuzzy Sphere
We study a multi-matrix model whose low temperature phase is a fuzzy sphere
that undergoes an evaporation transition as the temperature is increased. We
investigate finite size scaling of the system as the limiting temperature of
stability of the fuzzy sphere phase is approached. We find on theoretical
grounds that the system should obey scaling with specific heat exponent
\alpha=1/2, shift exponent \bar \lambda=4/3 and that the peak in the specific
heat grows with exponent \bar \omega=2/3. Using hybrid Monte Carlo simulations
we find good collapse of specific heat data consistent with a scaling ansatz
which give our best estimates for the scaling exponents as \alpha=0.50 \pm
0.01,\bar \lambda=1.41 \pm 0.08 and \bar \omega=0.66 \pm 0.08 .Comment: 30 pages, 10 figure
Quantum Field Theory in a Non-Commutative Space: Theoretical Predictions and Numerical Results on the Fuzzy Sphere
We review some recent progress in quantum field theory in non-commutative
space, focusing onto the fuzzy sphere as a non-perturbative regularisation
scheme. We first introduce the basic formalism, and discuss the limits
corresponding to different commutative or non-commutative spaces. We present
some of the theories which have been investigated in this framework, with a
particular attention to the scalar model. Then we comment on the results
recently obtained from Monte Carlo simulations, and show a preview of new
numerical data, which are consistent with the expected transition between two
phases characterised by the topology of the support of a matrix eigenvalue
distribution.Comment: This is a contribution to the Proc. of the O'Raifeartaigh Symposium
on Non-Perturbative and Symmetry Methods in Field Theory (June 2006,
Budapest, Hungary), published in SIGMA (Symmetry, Integrability and Geometry:
Methods and Applications) at http://www.emis.de/journals/SIGMA
Quantum canonical tensor model and an exact wave function
Tensor models in various forms are being studied as models of quantum
gravity. Among them the canonical tensor model has a canonical pair of
rank-three tensors as dynamical variables, and is a pure constraint system with
first-class constraints. The Poisson algebra of the first-class constraints has
structure functions, and provides an algebraically consistent way of
discretizing the Dirac first-class constraint algebra for general relativity.
This paper successfully formulates the Wheeler-DeWitt scheme of quantization of
the canonical tensor model; the ordering of operators in the constraints is
determined without ambiguity by imposing Hermiticity and covariance on the
constraints, and the commutation algebra of constraints takes essentially the
same from as the classical Poisson algebra, i.e. is first-class. Thus one could
consistently obtain, at least locally in the configuration space, wave
functions of "universe" by solving the partial differential equations
representing the constraints, i.e. the Wheeler-DeWitt equations for the quantum
canonical tensor model. The unique wave function for the simplest non-trivial
case is exactly and globally obtained. Although this case is far from being
realistic, the wave function has a few physically interesting features; it
shows that locality is favored, and that there exists a locus of configurations
with features of beginning of universe.Comment: 17 pages. Section 2 expanded to include fuzzy-space interpretation,
and other minor change
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