# Theory Seminar

## Constructing the Bulk of Sachdev-Ye-Kitaev (SYK) model

## Theory Seminar

## Theory seminar: The Schwarzian and black hole physics

**Title:** The Schwarzian and black hole physics

**Abstract:** In this talk, I will discuss the Schwarzian theory (relevant for low-energy SYK physics and Jackiw-Teitelboim gravity) from a 2d perspective. I will demonstrate how Schwarzian quantum mechanics is naturally embedded in 2d Liouville CFT. This perspective allows a direct computation of Schwarzian two- and four-point functions. Out-of-time ordered (OTO) four-point functions are also determined using the 2d R-matrix. The semi-classical limit of these expressions demonstrate various aspects of black holes, such as quasi-normal modes and eikonal shockwave expressions in the holographic bulk. In the end, I briefly discuss some generalizations to other theories. Mostly based on arXiv:1705.08408.

## Theory seminar: Path-Integral Complexity for Perturbed CFTs

## Theorey Seminar

## Dynamics of Near-Extremal Black Holes in AdS4

**Abstract:**

In this talk, I will discuss the dynamics of near-extremal Reissner-Nordstrom black holes in asymptotically four-dimensional Anti-de Sitter space (AdS4). In the spherically symmetric approximation and at low energies, the behaviour of the system in response to a probe scalar is well described by the Jackiw-Teitelboim (JT) model of gravity. In fact, this behaviour can be understood from symmetry considerations and arises due to the breaking of time reparametrisation invariance. The JT model has been analysed in considerable detail recently and related to the behaviour of the SYK model. The results that I will present indicate that features in these models which arise from symmetry considerations alone are more general and present quite universally in near-extremal black holes.

## Theory seminar

Title: probing beyond ETH at large c

Abstract: Eigenstate thermalization hypothesis (ETH) is a phenomena often observed in systems characterized by quantum chaos. In this talk, we study ETH in 2d CFTs with large central charges. In particular, we focus on observables consisting of bilocal "probe" operators $\mathcal{O}_L(x)\mathcal{O}_L(0)$. A sharp feature of ETH in this context is the so-called "forbidden" singularities, arising in the thermodynamic limit $c\to\infty$. We explore their resolutions by finite $c$ effects, and analyze the associated non-perturbative phenomena. We also discuss some interesting similarities between the related real-time dynamics and the spectral form factors in both the SYK model and BTZ black holes.

## Speed of Gravitational Waves as a New Probe of Ultra-light Dark Matter

## Baryogenesis, Dark Matter, Neutron-Antineutron Oscillation and Collider Signals

## Theory Seminar

Title: Baryogenesis, Dark Matter, Neutron-Antineutron Oscillation and Collider Signals

Abstract: We will discuss a simple model of low-energy baryon number violation in order to simultaneously explain the observed matter-antimatter asymmetry and dark matter relic density in the universe. The stability of dark matter is related to the stability of the proton. The model predicts a sizeable rate for the neutron-antineutron oscillation at low energy and a new type of monojet signal at the LHC. There exists an interesting complementarity between the observed baryon asymmetry, ratio of dark matter and baryon abundances, neutron-antineutron oscillation lifetime and the LHC monojet signal.