Opacity from Loops in AdS

A bstract We investigate how quantum dynamics affects the propagation of a scalar field in Lorentzian AdS. work momentum space, which propagator admits two spectral representations (denoted “conformal” and “momentum”) addition to closed-form one, all have simple split structure. Focusing on bubbles, we compute imaginary part self-energy Im? three representations, involves evaluation seemingly very different objects. explicitly prove their equivalence any dimension, derive some elementary asymptotic properties Im?. Using WKB-like approach timelike region, evaluate dressed with self-energy. find that dressing from loops exponentially dampens when one endpoints is IR rendering this region opaque propagation. This suppression may implications for field-theoretical model-building argue effective theory (EFT) paradigm, opacity induced by higher dimensional operators censors EFT breakdown. confirms earlier expectations literature. Specializing AdS 5 , determine universal contribution gravity.