Classically, a black hole only absorbs; anything crossing its horizon is lost forever. Quantum mechanically, Hawking showed that it also radiates at a temperature set by its mass. Fields and particles outside a black hole therefore behave like an open system in contact with a bath, i.e., they dissipate into the horizon and are stochastically kicked around by the outgoing radiation. This raises a natural question: can the interior be integrated out, leaving a field theory that lives purely outside the horizon? In this talk, I will show that for scalar and Yukawa theories on an AdS_{d+1} black brane, the answer is yes. The gravitational Schwinger-Keldysh (grSK) construction, which computes real-time correlators on a doubled geometry, collapses onto a single copy of the exterior, giving explicit Feynman rules built from causal propagators with vertices dressed by thermal occupation factors. I will describe how this picture extends to fermions and to arbitrary loop order.
Zoom Meeting: https://icts-res-in.zoom.us/j/92020032996?pwd=8whxbes4jMcuXZf98nZXDvF7NrkOfb.1
Meeting ID: 920 2003 2996
Passcode: 605030