Agenda
Mercredi 24 mai 2017
Invariant measure for quantum trajectories
Tristan Benoist (IMT, Université de Toulouse)
Axion Phenomenology from Unquenched Lattice QCD
Guido Martinelli (Università Roma “La Sapienza”)
The properties of the QCD axion can be studied from the dependence of strong interactions on the $\theta$-parameter. We present a study of the moments of the topological charge for temperatures up to around 600 MeV, obtained by lattice QCD simulations with 2+1 flavors at the physical quark masses. Our numerical results for the topological susceptibility, when compared to the instanton gas calculation, differ both in size and in the temperature dependence. We discuss the implications of these results for axion phenomenology, a comparison with other more recent studies and the prospects for future investigations. We also present some new results recently obtained at finer lattice spacing using metadynamics to reduce the systematic error due to the topological freezing.
What is absolutely continuous spectrum ?
Vojkan Jaksic (Department of Mathematics and Statistics, McGill University, Canada)
The Hamiltonian Description of Matter
P. J. Morrison* (Department of Physics, University of Texas at Austin)
Conventional field theories, classical versions of quantum field theories, possess a canonical structure in both their action functional and Hamiltonian descriptions. Alternatively, field theories that are typically used to describe the dynamics of matter, classical models developed for classical purposes, such as fluids, magnetofluids, plasma kinetic theories etc., possess structure with special properties. Loosely speaking, matter models correspond to flows on Poisson manifolds as opposed to more conventional symplectic manifolds, and this is manifested in the Poisson bracket having noncanonical form. In this talk I will survey this noncanonical structure and describe how it has been and continues to be used in applications.
*morrison chez physics.utexas.edu