Speaker
Description
The study of thermalisation in isolated systems was pioneered by Fermi-Pasta-Ulam-Tsingou (FPUT). In this talk I will present a new avenue towards the understanding of thermalisation, the presence of a power-law in the Fourier energy spectrum. A universal scaling exponent is obtained by mapping the FPUT model onto a pair of Burgers equations. Energy is transferred to higher Fourier modes like in “Burgers turbulence”, while ``shocks” develop on the lattice. Only at much longer times the system reaches energy equipartition. I will also present recent analytical results enabling the derivation of the average shock-time for general random initial conditions.
References:
-M. Gallone, M. Marian, A. Ponno and S. Ruffo:"Burgers turbulence in the FPUT chain", Phys. Rev. Lett. 114101 (2023)
-M. Gallone, A. Ponno and S. Ruffo:"Energy cascade and Burgers turbulence in the FPUT chain", Phys. Rev. E, 054212 (2024)
-M. Gallone, R. Grande, A. Ponno, S. Ruffo and E. Druais: "Random initial data and average shock time in the Fermi-Pasta-Ulam-Tsingou chain", Phys. Rev. Lett. to be published (2026)
