Analysis Seminar

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Coherent energy cascades in (semi-)random Hamiltonian systems

Speaker: Anxo Biasi, Galician Institute for High Energy Physics

Location: Warren Weaver Hall 1302

Date: Thursday, February 26, 2026, 11 a.m.

Synopsis:

The problem of Sobolev norm growth—namely, the search for mechanisms of energy transfer from low to arbitrarily high modes—has been intensively studied in Hamiltonian systems with an organized, deterministic structure of mode interactions, such as the cubic nonlinear Schrödinger equation. In this talk, I will present an extension of this problem to Hamiltonian systems dominated by random nonlinear interactions. I will introduce analytic solutions describing three types of energy cascades that lead either to unbounded growth or to finite-time blow-up of Sobolev norms. I will then present numerical simulations demonstrating the emergence of these dynamics from incoherent initial conditions. Taken together, these results demonstrate that coherent (phase-organized) energy cascades can be robust mechanisms of energy transfer even in systems with a random structure.