Search results for "Mathematical physics"
showing 10 items of 2687 documents
Hopf bifurcation at infinity for planar vector fields
2007
We study, from a new point of view, families of planar vector fields without singularities $ \{ X_{\mu}$  :  $-\varepsilon < \mu < \varepsilon\} $ defined on the complement of an open ball centered at the origin such that, at $\mu=0$, infinity changes from repellor to attractor, or vice versa. We also study a sort of local stability of some $C^1$ planar vector fields around infinity.
Symbolic dynamics in a binary asteroid system
2020
We highlight the existence of a topological horseshoe arising from a a--priori stable model of the binary asteroid dynamics. The inspection is numerical and uses correctly aligned windows, as described in a recent paper by A. Gierzkiewicz and P. Zgliczy\'nski, combined with a recent analysis of an associated secular problem.
Analysis of multilayer adsorption models without screening
1991
A class of recently introduced irreversible multilayer adsorption models without screening is analysed. The basic kinetic process of these models leads to power law behaviour for the decay of the jamming coverage as a function of height. The authors find the exact value for the power law exponent. An approximate analytical treatment of these models and previous Monte Carlo simulations are found to be in good agreement.
f2(1810) as a triangle singularity
2017
We perform calculations showing that a source producing ${K}^{*}{\overline{K}}^{*}$ in $J=2$ and $L=0$ gives rise to a triangle singularity at 1810 MeV with a width of about 200 MeV from the mechanism ${K}^{*}\ensuremath{\rightarrow}\ensuremath{\pi}K$ and then $K{\overline{K}}^{*}$ merging into the ${a}_{1}(1260)$ resonance. We suggest that this is the origin of the present ${f}_{2}(1810)$ resonance and propose to look at the $\ensuremath{\pi}{a}_{1}(1260)$ mode in several reactions to clarify the issue.
An immune system model in discrete time based on the analogy with the central nervous system
1988
Jerne's model for the immune system formulated in terms of a neural network recently proposed by Weisbuch and Atlan is generalized to interactions with continuous coupling coefficients. It is shown that even the extended model can be solved analytically without the aid of computer simulations and exhibits one additional attractor, which corresponds to a configuration with high concentrations of active killer cells eventually causing death of the organism.
Econophysics: Scaling and its breakdown in finance
1997
We discuss recent empirical results obtained by analyzing high-frequency data of a stock market index, the Standard and Poor’s 500. We focus on the scaling properties and on its breakdown of the index dynamics. A simple stochastic model, the truncated Levy flight, is illustrated. Successes and limitations of this model are presented. A discussion about similarities and differences between the scaling properties observed in financial markets and in fully developed turbulence is also provided.
Long time behavior for a dissipative shallow water model
2013
We consider the two-dimensional shallow water model derived by Levermore and Sammartino (Nonlinearity 14,2001), describing the motion of an incompressible fluid, confined in a shallow basin, with varying bottom topography. We construct the approximate inertial manifolds for the associated dynamical system and estimate its order. Finally, considering the whole domain R^2 and under suitable conditions on the time dependent forcing term, we prove the L^2 asymptotic decay of the weak solutions.
The Regularized Hadamard Expansion
2017
A local expansion is proposed for two-point distributions involving an ultraviolet regularization in a four-dimensional globally hyperbolic space-time. The regularization is described by an infinite number of functions which can be computed iteratively by solving transport equations along null geodesics. We show that the Cauchy evolution preserves the regularized Hadamard structure. The resulting regularized Hadamard expansion gives detailed and explicit information on the global dynamics of the regularization effects.
Toward a formalization of a two traders market with information exchange
2014
This paper shows that Hamiltonians and operators can also be put to good use even in contexts which are not purely physics based. Consider the world of finance. The work presented here {models a two traders system with information exchange with the help of four fundamental operators: cash and share operators; a portfolio operator and an operator reflecting the loss of information. An information Hamiltonian is considered and an additional Hamiltonian is presented which reflects the dynamics of selling/buying shares between traders. An important result of the paper is that when the information Hamiltonian is zero, portfolio operators commute with the Hamiltonian and this suggests that the dy…
Induced-Gravity Inflation in Supergravity Confronted with Planck2013 and BICEP2
2015
Supersymmetric versions of induced-gravity inflation are f ormulated within Super- gravity (SUGRA) employing two gauge singlet chiral superfie lds. The proposed superpotential is uniquely determined by applying a continuous R and a discrete Z2 symmetry. We also employ a logarithmic Kahler potential respecting the symmetries above and including all the allowed terms up to fourth order in powers of the various fields. When the Kahle r manifold exhibits a no-scale-type symmetry, the model predicts spectral index ns ≃ 0.963 and tensor-to-scalar r ≃ 0.004. Beyond no-scale SUGRA, ns and r depend crucially on the coefficient kSΦ involved in the fourth order term, which mixes the inflaton Φ with th…