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Department of Mathematical Sciences

Seminar Archives

On this page you can find information about seminars in this and previous academic years, where available on the database.

CPT Student Seminar: Adiabatic hydrodynamics and the eightfold way to dissipation

Presented by Felix Haehl, Durham University

9 February 2015 17:00 in OC218

Hydrodynamics is the low-energy effective field theory which describes the long-wavelength fluctuations of any interacting QFT. It is characterized by the gradient expansion of an energy-momentum tensor and charge current which satisfy certain dynamical equations. On top of this, an additional constraint has to be imposed which ensures the second law of thermodynamics is respected by any fluid flow. In this talk I will describe a complete solution to hydrodynamic transport at all orders in the gradient expansion compatible with the second law constraint. A key ingredient is the notion of adiabaticity, which allows to take hydrodynamics off-shell. I will furthermore argue for a new symmetry principle, an Abelian gauge invariance that is the underlying reason for adiabaticity in hydrodynamics and elucidates the origin of the second law constraint. This new symmetry should be viewed as the macroscopic manifestation of the microscopic KMS condition. In non-equilibrium situations the macroscopic "KMS gauge invariance" enables us to keep Feynman-Vernon influence functionals under control and to formulate an off-shell effective action that encompasses the entirety of adiabatic fluids in a consistent way.

A copy of the slides for this talk may be found at the above link.

Contact for more information

A gathering of mathematicians from the CPT group with physicists from IPPP, we meet to discuss our work in a relaxed and friendly environment.

An archive of previous years talks is kept here.