4,031 research outputs found
Asymptotic Laplacian-Energy-Like Invariant of Lattices
Let denote the Laplacian eigenvalues of
with vertices. The Laplacian-energy-like invariant, denoted by , is a novel topological index. In this paper, we
show that the Laplacian-energy-like per vertex of various lattices is
independent of the toroidal, cylindrical, and free boundary conditions.
Simultaneously, the explicit asymptotic values of the Laplacian-energy-like in
these lattices are obtained. Moreover, our approach implies that in general the
Laplacian-energy-like per vertex of other lattices is independent of the
boundary conditions.Comment: 6 pages, 2 figure
Random Tensors and Quantum Gravity
We provide an informal introduction to tensor field theories and to their
associated renormalization group. We focus more on the general motivations
coming from quantum gravity than on the technical details. In particular we
discuss how asymptotic freedom of such tensor field theories gives a concrete
example of a natural "quantum relativity" postulate: physics in the deep
ultraviolet regime becomes asymptotically more and more independent of any
particular choice of Hilbert basis in the space of states of the universe.Comment: Section 6 is essentially reproduced from author's arXiv:1507.04190
for self-contained purpose of the revie
On Connected Diagrams and Cumulants of Erdos-Renyi Matrix Models
Regarding the adjacency matrices of n-vertex graphs and related graph
Laplacian, we introduce two families of discrete matrix models constructed both
with the help of the Erdos-Renyi ensemble of random graphs. Corresponding
matrix sums represent the characteristic functions of the average number of
walks and closed walks over the random graph. These sums can be considered as
discrete analogs of the matrix integrals of random matrix theory.
We study the diagram structure of the cumulant expansions of logarithms of
these matrix sums and analyze the limiting expressions in the cases of constant
and vanishing edge probabilities as n tends to infinity.Comment: 34 pages, 8 figure
The Tensor Track: an Update
The tensor track approach to quantum gravity is based on a new class of
quantum field theories, called tensor group field theories (TGFTs). We provide
a brief review of recent progress and list some desirable properties of TGFTs.
In order to narrow the search for interesting models, we also propose a set of
guidelines for TGFT's loosely inspired by the Osterwalder-Schrader axioms of
ordinary Euclidean QFT.Comment: 12 pages, 1 figure. This paper is based on a talk given at the XXIX
International Colloquium on Group-Theoretical Methods in Physics in Tian-Jin
(China), very minor change
Equality of Lifshitz and van Hove exponents on amenable Cayley graphs
We study the low energy asymptotics of periodic and random Laplace operators
on Cayley graphs of amenable, finitely generated groups. For the periodic
operator the asymptotics is characterised by the van Hove exponent or zeroth
Novikov-Shubin invariant. The random model we consider is given in terms of an
adjacency Laplacian on site or edge percolation subgraphs of the Cayley graph.
The asymptotic behaviour of the spectral distribution is exponential,
characterised by the Lifshitz exponent. We show that for the adjacency
Laplacian the two invariants/exponents coincide. The result holds also for more
general symmetric transition operators. For combinatorial Laplacians one has a
different universal behaviour of the low energy asymptotics of the spectral
distribution function, which can be actually established on quasi-transitive
graphs without an amenability assumption. The latter result holds also for long
range bond percolation models
The Tensor Track, III
We provide an informal up-to-date review of the tensor track approach to
quantum gravity. In a long introduction we describe in simple terms the
motivations for this approach. Then the many recent advances are summarized,
with emphasis on some points (Gromov-Hausdorff limit, Loop vertex expansion,
Osterwalder-Schrader positivity...) which, while important for the tensor track
program, are not detailed in the usual quantum gravity literature. We list open
questions in the conclusion and provide a rather extended bibliography.Comment: 53 pages, 6 figure
Decentralized Maximum Likelihood Estimation for Sensor Networks Composed of Nonlinearly Coupled Dynamical Systems
In this paper we propose a decentralized sensor network scheme capable to
reach a globally optimum maximum likelihood (ML) estimate through
self-synchronization of nonlinearly coupled dynamical systems. Each node of the
network is composed of a sensor and a first-order dynamical system initialized
with the local measurements. Nearby nodes interact with each other exchanging
their state value and the final estimate is associated to the state derivative
of each dynamical system. We derive the conditions on the coupling mechanism
guaranteeing that, if the network observes one common phenomenon, each node
converges to the globally optimal ML estimate. We prove that the synchronized
state is globally asymptotically stable if the coupling strength exceeds a
given threshold. Acting on a single parameter, the coupling strength, we show
how, in the case of nonlinear coupling, the network behavior can switch from a
global consensus system to a spatial clustering system. Finally, we show the
effect of the network topology on the scalability properties of the network and
we validate our theoretical findings with simulation results.Comment: Journal paper accepted on IEEE Transactions on Signal Processin
The Tensor Theory Space
The tensor track is a background-independent discretization of quantum
gravity which includes a sum over all topologies. We discuss how to define a
functional renormalization group flow and the Wetterich equation in the
corresponding theory space. This space is different from the Einsteinian theory
space of asymptotic safety. It includes all fixed-rank tensor-invariant
interactions, hence generalizes matrix models and the (Moyal) non-commutative
field theory space.Comment: This short note is intended as a complement to arXiv:1311.1461, to
appear in the Proceedings of the Workshop on Noncommutative Field Theory and
Gravity in Corfu September 2013, Fortshritt. Phys. 201
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