Effective field theories for non-equilibrium many-body systems

Descripción del proyecto

Un nuevo enfoque teórico para modelizar sistemas fuera de equilibrio

Los fenómenos fuera de equilibrio menoscaban la comprensión de los sistemas de muchos cuerpos. Hasta ahora, los sistemas lejos del equilibrio térmico no podían analizarse con un marco que tuviera en cuenta el ruido térmico estocástico. El objetivo del proyecto NonEqbSK, financiado por las Acciones Marie Skłodowska-Curie, es investigar sistemas de fluidos lejos del equilibrio mediante el marco Schwinger-Keldysh. Este marco innovador ofrece una comprensión sistemática de las fluctuaciones térmicas y la disipación y, además, es idóneo para construir modelos que describan fenómenos fuera de equilibrio en sistemas de muchos cuerpos. Los resultados del proyecto tendrán repercusiones de gran calado para la física de alta energía y la física de la materia condensada, sobre todo en lo referente a la búsqueda del punto crítico de la cromodinámica cuántica en colisionadores de iones pesados, la modelización de sistemas vivos y el desarrollo de membranas biofísicas.

Objetivo

Non-equilibrium phenomena continue to challenge our understanding of many-body systems appearing in nature. Macroscopic processes are generally irreversible due to dissipation. Reconciling this irreversibility with the unitarity of quantum mechanics has been one of the long-standing puzzles in physics. To date, we lack a systematic framework to account for stochastic thermal noise in many-body dynamics that becomes increasingly important as we leave equilibrium. The situation is particularly dire in systems that naturally operate far from equilibrium, such as fluids near a critical point, actively driven fluids, or fluids fluctuating in a confined volume, as the validity of existing models is limited.

The goal of this proposal is to investigate these systems in the context of the newly developed Schwinger-Keldysh framework for non-equilibrium effective field theories. The new framework offers a systematic understanding of thermal fluctuations and dissipation starting from an action principle, and is suitable for constructing models describing non-equilibrium phenomena in many-body systems. During this fellowship, I will develop effective field theories specialised to the non-equilibrium systems mentioned above, and investigate their repercussions for observed phenomena. These results will have far-reaching impact in the fields of high-energy physics and condensed matter physics, especially concerning the hunt for the QCD critical point at heavy-ion colliders, modelling of living systems in biophysics, and biophysical membranes. This work will also provide insights into the broader physical problems such as the emergence of dissipation from microscopic principles and the quantum nature of gravity via the AdS/CFT correspondence.

The increased visibility that I will gain in the scientific community due to these results, along with the training and experience I will obtain during this fellowship, will help me establish myself as an independent scientist in the future.