SYK wormhole formation in real time

We study the real time formation of the ground state of two coupled SYK models. This is a highly entangled state which is close to the thermofield double state and can be viewed as a wormhole. We start from a high temperature state, we let it cool by coupling to a cold bath. We numerically solve for the large N dynamics. Our main result is that the system forms a wormhole by going through a region with negative specific heat, taking time that is independent of N. The dynamics is smooth everywhere and it seems to follow the equilibrium thermodynamic configurations of the microcanonical ensemble. Also we comment on the relation between this coupled SYK model and Jackiw-Teitelboim gravity theory with bulk fields.

Phases of holographic interfaces

We compute the phase diagram of the simplest holographic bottom-up model of conformal interfaces. The model consists of a thin domain wall between three-dimensional Anti-de Sitter (AdS) vacua, anchored on a boundary circle. We distinguish five phases depending on the existence of a black hole, the intersection of its horizon with the wall, and the fate of inertial observers. We show that, like the Hawking-Page phase transition, the capture of the wall by the horizon is also a first order transition and comment on its field-theory interpretation. The static solutions of the domain-wall equations include gravitational avatars of the Faraday cage, black holes with negative specific heat, and an intriguing phenomenon of suspended vacuum bubbles corresponding to an exotic interface/anti-interface fusion. Part of our analysis overlaps with recent work by Simidzija and Van Raamsdonk but the interpretation is different.

Thermodynamic analysis of a long-range interacting spin system

A long-range interacting Fermi chain placed in the uniform and the staggered magnetic field is studied via the micro-canonical approach. The relation between the entropy and the energy of the system is obtained by counting the number of microscopic states. We find that this system is non-ergodic and can exhibit first-order phase transition, second-order phase transition, or both. The microcanonical ensemble predicts negative specific heat regions and temperature jumps. Moreover, the global phase diagram of the system is constructed.

STABLE AND UNSTABLE EQUILIBRIA OF UNIFORMLY ROTATING SELF-GRAVITATING CYLINDERS

The equilibrium configurations of self-gravitating uniformly rotating isothermal cylinders in contact with a heat bath and their stability is studied by recently derived analytical techniques. The known critical temperature Tc obtained by Katz and Lynden-Bell is found to be a stability threshold with respect to axially symmetric perturbations. We provide the almost explicit expression of negative specific heat solutions whose densities are sharply concentrated either near the symmetry axis or near some off-axis filaments as [Formula: see text]. The critical angular frequency observed numerically in literature is found to be the threshold value for the existence of these off-axis filaments. This is in striking contrast with the static case analyzed by Katz and Lynden-Bell where equilibrium configurations are found only if T > Tc and no negative specific heat equilibria exists at all. Metastability of the free energy's relative maximizers for T ≤ Tc is also discussed. Those off-axis configurations were predicted in the study of negative temperature states for guiding-centre plasmas and vortex systems.