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We study a Fermi-Pasta-Ulam-like chain with realistic potentials, which models a unidimensional solid in contact with heat baths at some temperature. We formulate an explicit analytical expression for the probability density of bonding…

Statistical Mechanics · Physics 2015-06-16 Roman Belousov , Paolo De Gregorio , Lamberto Rondoni , Livia Conti

The Fermi--Pasta--Ulam--Tsingou (FPUT) system, describing the evolution of $N$ coupled harmonic oscillators, has been the subject of much attention since the 1950's when experiments which contradicted predictions of thermalization of the…

Analysis of PDEs · Mathematics 2026-05-20 Katja Vassilev , Boyang Wu

We introduce a generalized $d$-dimensional Fermi-Pasta-Ulam (FPU) model in presence of long-range interactions, and perform a first-principle study of its chaos for $d=1,2,3$ through large-scale numerical simulations. The nonlinear…

Statistical Mechanics · Physics 2016-06-28 Debarshee Bagchi , Constantino Tsallis

Over the past decade, substantial progress has been made in clarifying a central question of the Fermi-Pasta-Ulam-Tsingou problem: whether weakly nonlinear lattice systems thermalize and, if so, through what mechanisms. The current…

Statistical Mechanics · Physics 2026-03-25 Weicheng Fu , Zhen Wang , Wei Lin , Dahai He , Jiao Wang , Yong Zhang , Hong Zhao

We investigate the diffusive motion of an overdamped classical particle in a 1D random potential using the mean first-passage time formalism and demonstrate the efficiency of this method in the investigation of the large-time dynamics of…

Superconductivity · Physics 2009-10-31 D. A. Gorokhov , G. Blatter

We present a numerical study of dynamical correlations (structure factors) of the long-range generalization of the Fermi-Pasta-Ulam oscillator chain, where the strength of the interaction between two lattice sites decays as a power $\alpha$…

Statistical Mechanics · Physics 2019-06-11 Pierfrancesco Di Cintio , Stefano Iubini , Stefano Lepri , Roberto Livi

We examine Fermi-type acceleration at relativistic shocks, and distinguish between the initial boost of the first shock crossing cycle, where the energy gain per particle can be very large, and the Fermi process proper with repeated shock…

Astrophysics · Physics 2009-10-31 Yves A. Gallant , Abraham Achterberg , John G. Kirk , Axel W. Guthmann

The Fermi-Pasta-Ulam-Tsingou (FPUT) problem addresses fundamental questions in statistical physics, and attempts to understand the origin of recurrences in the system have led to many great advances in nonlinear dynamics and mathematical…

Statistical Mechanics · Physics 2023-09-06 Santhosh Ganapa

We study the dynamics of Fermi-Pasta-Ulam chains with both harmonic and anharmonic power-law long-range interactions. We show that the dynamics is described in the continuum limit by a generalized fractional Boussinesq differential…

Statistical Mechanics · Physics 2018-07-31 G. N. B. Chendjou , J. P. Nguenang , A. Trombettoni , T. Dauxois , R. Khomeriki , S. Ruffo

This review provides an up-to-date account of energy transport in Fermi-Pasta-Ulam-Tsingou (FPUT) chains, a key testbed for nonequilibrium statistical physics. We discuss the transition from the historical puzzle of thermalization to the…

Statistical Mechanics · Physics 2026-02-18 Stefano Lepri , Roberto Livi , Antonio Politi

The linear response to temperature variations is well characterised for equilibrium systems but a similar theory is not available, for example, for inertial heat conducting systems, whose paradigm is the Fermi-Pasta-Ulam (FPU) model driven…

Statistical Mechanics · Physics 2018-02-09 Federico D'Ambrosio , Marco Baiesi

We consider the Fermi-Pasta-Ulam-Tsingou (FPUT) chain composed by $N \gg 1$ particles and periodic boundary conditions, and endow the phase space with the Gibbs measure at small temperature $\beta^{-1}$. Given a fixed ${1\leq m \ll N}$, we…

Mathematical Physics · Physics 2021-03-23 T. Grava , A. Maspero , G. Mazzuca , A. Ponno

In their seminal work, Fermi, Pasta, Ulam and Tsingou explored the connection between statistical mechanics and dynamical properties, such as chaos and ergodicity. Even today, seventy years later, the topic is not fully understood: while…

Statistical Mechanics · Physics 2026-04-01 Marco Baldovin , Marco Cattaneo , Dario Lucente , Paolo Muratore-Ginanneschi , Angelo Vulpiani

We will discuss various aspects of thermalization, chaos and hydrodynamics in one dimensional classical Hamiltonian systems. We study two problems. First, we will revisit the Fermi-Pasta-Ulam-Tsingou (FPUT) problem in order to understand…

Chaotic Dynamics · Physics 2023-05-11 Santhosh Ganapa

We study the broadening of initially localized wave packets in a quasi one-dimensional diamond ladder with interacting, spinless fermions. The lattice possesses a flat band causing localization. We place special focus on the transition away…

Statistical Mechanics · Physics 2024-06-04 Mirko Daumann , Thomas Dahm

We present a non-perturbative, mean-field theory for the Fermi-Pasta-Ulam-Tsingou model with quartic interaction, capturing the quasiperiodic features shown by the system at all energies in the thermodynamic limit. Starting from the true…

Statistical Mechanics · Physics 2025-12-02 Antonio Ponno , Giacomo Gradenigo , Marco Baldovin , Angelo Vulpiani

We propose an experiment to probe ferromagnetic phenomena in an ultracold Fermi gas, while alleviating the sensitivity to three-body loss and competing many-body instabilities. The system is initialized in a small pitch spin spiral, which…

Quantum Gases · Physics 2015-05-19 G. J. Conduit , Ehud Altman

We show, without relying on any unproven assumptions, that a low-density free fermion chain exhibits thermalization in the following (restricted) sense. We choose the initial state as a pure state drawn randomly from the Hilbert space in…

Statistical Mechanics · Physics 2026-04-13 Naoto Shiraishi , Hal Tasaki

The Alpha version of the Fermi-Pasta-Ulam problem is revisited through direct numerical simulations and an application of weak turbulence theory. The energy spectrum, initialized with a large scale excitation, is traced through a series of…

Chaotic Dynamics · Physics 2007-05-23 Joseph A. Biello , Peter R. Kramer , Yury Lvov

We discuss a class of mechanical models of thermometers and their minimal requirements to determine the temperature for systems out of the common scope of thermometry. In particular we consider: 1) anharmonic chains with long time of…

Statistical Mechanics · Physics 2017-11-08 M. Baldovin , A. Puglisi , A. Sarracino , A. Vulpiani