Title: Diffusion in a magnetic field in (2+1)-dimensions
Abstract: Even with the simplifying assumption of non-dynamical (external) electromagnetic fields, magnetohydrodynamics is a technically subtle framework for understanding the long wavelength and low frequency regime of interacting theories. One of these technicalities is that for many models of interdisciplinary relevance the magnetic field is a constant in equilibrium. Intuitively however, for momentum to be approximately conserved and enter the hydrodynamic description, the magnetic field must vanish at leading order.
In this talk I will review recent work that sheds light on some of the unique features of magnetohydrodynamics in (2+1)-dimensions, with a particular emphasis on diffusion. I will show that there is a qualitative and quantitative improvement in matching holographic and hydrodynamic correlators if one correctly accounts for the magnetic field being non-zero in the background. Consequently, I will give conclusive evidence that there is a non-zero incoherent Hall conductivity in the absence of parity violation that was missed in previous approaches. Finally, I will discuss some ways in which this new approach can be applied to non-stringy systems.
Date: 14th September 2022
Place: Genoa, Italy.
Title: When the scalings aren't balanced
Abstract: I will discuss recent work on anisotropic scaling invariance in various aspects of quantum theory. In particular I will focus on situations where the naive continuous scale invariance is anomalously broken to an infinite discrete subgroup, and discuss the corresponding quantum critical phase transition. We will discover the importance of limit cycles in the renormalisation group picture of these theories and their relevance to the existence of the transition. Finally I will highlight the future directions that this research programme can take by discussing concrete problems to be solved.
Date: 4th June 2018
Place: ICTS, USTC, Hefei, Anhui, PRC.