Abstract:
“Linear response theory is an incredibly powerful calculation tool. We apply this framework
in quantum field theory to a variety of models originated from distinct areas in theoretical
physics and for different reasons. In the context of black hole holography, we consider a
quench model where we investigate effective thermalization as well as the boundary signal of
the so called evanescent modes which indicate the presence of a black hole like object in the
bulk. The problem of quantum thermalization plays a central role within the holographic
duality between thermal states in the boundary field theory and black hole like objects in the
bulk. However, quantum thermalization is also an interesting question in itself from a
fundamental point of view and with that motivation we continue to explore this phenomenon
further. Inspired by recent progress in understanding how operators in quantum field theories
thermalize, which occurs even when considering integrable models, we investigate the so
called operator thermalization hypothesis. We focus on gauge theories at finite temperature
with a large number of fields which present a phase transition between the low-temperature
and high-temperature regimes. In particular, these theories are the so called vector model and
the adjoint matrix model. Last, within the common background of linear response theory we
investigate transport properties in a family of Weyl semimetal systems. Concretely, we
develop a general analytic method to compute the magneto-optical conductivity of these
systems in the presence of an external magnetic field aligned with the tilt of the spectrum.”