The Universal Phase Space of AdS3 Gravity
Carlos Scarinci, Kirill Krasnov
TL;DR
The paper presents a unified, explicit description of the AdS3 gravity phase space by embedding all fixed-topology moduli spaces into a universal space parametrized by two copies of the universal Teichmüller space ${\mathcal{T}}(1)$. It develops two complementary parametrizations—a maximal-surface cotangent-bundle picture and a generalized Mess map to ${\mathcal{T}}(1)\times{\mathcal{T}}(1)$—and demonstrates their equivalence as a symplectomorphism, grounded in the Chern-Simons formulation. The work connects holographic Fefferman-Graham data (stress tensor, Brown-Henneaux charges) to Bers-embedding quadratic differentials, giving explicit infinitesimal relations and formulas for charges, and clarifies how bulk moduli and asymptotic excitations coexist in a single, universal framework. It also clarifies how the bulk and boundary descriptions are related through harmonic decompositions of minimal Lagrangian maps and establishes a formal symplectic structure on the universal phase space, paving the way for potential quantum treatments and entropy investigations in AdS3 gravity.
Abstract
We describe what can be called the "universal" phase space of AdS3 gravity, in which the moduli spaces of globally hyperbolic AdS spacetimes with compact spatial sections, as well as the moduli spaces of multi-black-hole spacetimes are realized as submanifolds. The universal phase space is parametrized by two copies of the Universal Teichmüller space T(1) and is obtained from the correspondence between maximal surfaces in AdS3 and quasisymmetric homeomorphisms of the unit circle. We also relate our parametrization to the Chern-Simons formulation of 2+1 gravity and, infinitesimally, to the holographic (Fefferman-Graham) description. In particular, we obtain a relation between the generators of quasiconformal deformations in each T(1) sector and the chiral Brown-Henneaux vector fields. We also relate the charges arising in the holographic description (such as the mass and angular momentum of an AdS3 spacetime) to the periods of the quadratic differentials arising via the Bers embedding of T(1)xT(1). Our construction also yields a symplectic map from T*T(1) to T(1)xT(1) generalizing the well-known Mess map in the compact spatial surface setting.
