Separable Hamiltonian systems either in sphero-conical coordinates on a $S^2$ sphere or in elliptic coordinates on a ${mathbb R}^2$ plane are described in an unified way. A back and forth route connecting these Liouville Type I separable systems is unveiled. It is shown how the gnomonic projection and its inverse map allow us to pass from a Liouville Type I separable system with an spherical configuration space to its Liouville Type I partner where the configuration space is a plane and back. Several selected spherical separable systems and their planar cousins are discussed in a classical context.
We prove the equivalence between two explicit expressions for two-point Witten-Kontsevich correlators obtained by M. Bertola, B. Dubrovin, D. Yang and by P. Zograf.
This work is devoted to show an equivalent description for the most probable transition paths of stochastic dynamical systems with Brownian noise, based on the theory of Markovian bridges. The most probable transition path for a stochastic dynamical system is the minimizer of the Onsager-Machlup action functional, and thus determined by the Euler-Lagrange equation (a second order differential equation with initial-terminal conditions) via a variational principle. After showing that the Onsager-Machlup action functional can be derived from a Markovian bridge process, we first demonstrate that, in some special cases, the most probable transition paths can be determined by first order deterministic differential equations with only a initial condition. Then we show that for general nonlinear stochastic systems with small noise, the most probable transition paths can be well approximated by solving a first order differential equation or an integro differential equation on a certain time interval. Finally, we illustrate our results with several examples.
In this paper, the general disagreement of the geometrical lyapunov exponent with lyapunov exponent from tangent dynamics is addressed. It is shown in a quite general way that the vector field of geodesic spread $xi^k_G$ is not equivalent to the tangent dynamics vector $xi^k_T$ if the parameterization is not affine and that results regarding dynamical stability obtained in the geometrical framework can differ qualitatively from those in the tangent dynamics. It is also proved in a general way that in the case of Jacobi metric -frequently used non affine parameterization-, $xi^k_G$ satisfies differential equations which differ from the equations of the tangent dynamics in terms that produce parametric resonance, therefore, positive exponents for systems in stable regimes.
We present simple, physically motivated, examples where small geometric changes on a two-dimensional graph $mathbb{G}$, combined with high disorder, have a significant impact on the spectral and dynamical properties of the random Schrodinger operator $-A_{mathbb{G}}+V_{omega}$ obtained by adding a random potential to the graphs adjacency operator. Differently from the standard Anderson model, the random potential will be constant along any vertical line, i.e $V_{omega}(n)=omega(n_1)$, for $n=(n_1,n_2)in mathbb{Z}^2$, hence the models exhibit long range correlations. Moreover, one of the models presented here is a natural example where the transient and recurrent components of the absolutely continuous spectrum, introduced by Avron and Simon, coexist and allow us to capture a sharp phase transition present in the model.
A trajectory isomorphism between the two Newtonian fixed center problem in the sphere and two associated planar two fixed center problems is constructed by performing two simultaneous gnomonic projections in $S^2$. This isomorphism converts the original quadratures into elliptic integrals and allows the bifurcation diagram of the spherical problem to be analyzed in terms of the corresponding ones of the planar systems. The dynamics along the orbits in the different regimes for the problem in $S^2$ is expressed in terms of Jacobi elliptic functions.
M.A. Gonzalez Leon
,J. Mateos Guilarte
,M. de la Torre Mayado
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(2018)
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"Equivalence between Type I Liouville dynamical systems in the plane and the sphere"
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M. A. Gonzalez Leon
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