00-133 PONNO A.,GALGANI L., GUERRA F.

An analytical estimate of stochasticity thresholds in Fermi-Pasta-Ulam and $\phi^4$ models. (327K, PostScript) Mar 29, 00

Abstract , Paper (src), View paper (auto. generated ps), Index of related papers

Abstract. We consider an infinitely extended FPU model, and we show that the slow modulating amplitude of a narrow wave packet asymptotically satisfies the Nonlinear Schrodinger equation (NLS). It is well known that NLS presents a threshold below which the packet width remains narrow. We give an analytical estimate of such a threshold; we also make a comparison with the numerical results known to us, and show they are in remarkable agreement with our estimate. Analogous results are found for the $\phi^4$ model.

Files: 00-133.src( 00-133.keywords , ponno1.ps )