Abstract

Conformal interfaces, where two conformal field theories (CFTs) meet, offer a rich landscape of physical phenomena. A central observable is the fraction of energy that is reflected or transmitted in a scattering process at the interface. In two spacetime dimensions this process is universal: the result does not depend on the details of the incoming state. Nevertheless, working out the ratio at strong coupling is far from straightforward. In higher dimensions the problem becomes even more complicated, since conformal symmetry is reduced and the outcome can depend on the angular profile of the initial state. Holography provides a way to tackle these difficulties by mapping strongly coupled CFT dynamics to dual gravitational problems. In this talk, I will review two holographic calculations of reflection and transmission at two-dimensional conformal interfaces: one involving a gravitational dual with thin branes, often encountered in the study of entanglement islands, and another using smooth domain walls in three-dimensional gravity, including Janus interfaces. I will then describe our recent progress towards extending these ideas to higher dimensions, focusing on how different incoming states can be modelled in the thin-brane setup.