3,660 research outputs found
Bethe ansatz at q=0 and periodic box-ball systems
A class of periodic soliton cellular automata is introduced associated with
crystals of non-exceptional quantum affine algebras. Based on the Bethe ansatz
at q=0, we propose explicit formulas for the dynamical period and the size of
certain orbits under the time evolution in A^{(1)}_n case.Comment: 12 pages, Introduction expanded, Summary added and minor
modifications mad
Dynamical Systems, Stability, and Chaos
In this expository and resources chapter we review selected aspects of the
mathematics of dynamical systems, stability, and chaos, within a historical
framework that draws together two threads of its early development: celestial
mechanics and control theory, and focussing on qualitative theory. From this
perspective we show how concepts of stability enable us to classify dynamical
equations and their solutions and connect the key issues of nonlinearity,
bifurcation, control, and uncertainty that are common to time-dependent
problems in natural and engineered systems. We discuss stability and
bifurcations in three simple model problems, and conclude with a survey of
recent extensions of stability theory to complex networks.Comment: 28 pages, 10 figures. 26/04/2007: The book title was changed at the
last minute. No other changes have been made. Chapter 1 in: J.P. Denier and
J.S. Frederiksen (editors), Frontiers in Turbulence and Coherent Structures.
World Scientific Singapore 2007 (in press
Experimental vs. Numerical Eigenvalues of a Bunimovich Stadium Billiard -- A Comparison
We compare the statistical properties of eigenvalue sequences for a gamma=1
Bunimovich stadium billiard. The eigenvalues have been obtained by two ways:
one set results from a measurement of the eigenfrequencies of a superconducting
microwave resonator (real system) and the other set is calculated numerically
(ideal system). The influence of the mechanical imperfections of the real
system in the analysis of the spectral fluctuations and in the length spectra
compared to the exact data of the ideal system are shown. We also discuss the
influence of a family of marginally stable orbits, the bouncing ball orbits, in
two microwave stadium billiards with different geometrical dimensions.Comment: RevTex, 8 pages, 8 figures (postscript), to be published in Phys.
Rev.
Cosmological-Billiards Groups and self-adjoint BKL Transfer Operators
Cosmological billiards arise as a map of the solution of the Einstein
equations, when the most general symmetry for the metric tensor is
hypothesized, and points are considered as spatially decoupled in the
asymptotic limit towards the cosmological singularity, according to the BKL
(Belinski Khalatnikov Lifshitz) paradigm. In dimensions, two kinds of
cosmological billiards are considered: the so-called 'big billiard' which
accounts for pure gravity, and the 'small billiard', which is a
symmetry-reduced version of the previous one, and is obtained when the
'symmetry walls' are considered. The solution of Einstein field equations is
this way mapped to the (discrete) Poincar\'e map of a billiard ball on the
sides of a triangular billiard table, in the Upper Poincar\'e Half Plane
(UPHP). The billiard modular group is the scheme within which the dynamics of
classical chaotic systems on surfaces of constant negative curvature is
analyzed. The periodic orbits of the two kinds of billiards are classified,
according to the different symmetry-quotienting mechanisms. The differences
with the description implied by the billiard modular group are investigated and
outlined. In the quantum regime, the eigenvalues (i.e. the sign that
wavefunctions acquire according to quantum BKL maps) for periodic phenomena of
the BKL maps on the Maass wavefunctions are classified. The complete spectrum
of the semiclassical operators which act as BKL map for periodic orbits is
obtained. Differently form the case of the modular group, here it is shown that
the semiclassical transfer operator for Cosmological Billiards is not only the
adjoint operator of the one acting on the Maass waveforms, but that the two
operators are the same \it{self-adjoint} operator, thus outlining a different
approach to the Langlands Jaquet correspondence.Comment: 12 pages, 2 figure
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