Miranda C. N. Cheng

Quantum Geometry of Refined Topological Strings

A bstractWe consider branes in refined topological strings. We argue that their wavefunctions satisfy a Schrödinger equation depending on multiple times and prove this in the case where the topological string has a dual matrix model description. Furthermore, in the limit where one of the equivariant rotations approaches zero, the brane partition function satisfies a time-independent Schrödinger equation. We use this observation, as well as the back reaction of the brane on the closed string geometry, to offer an explanation of the connection between integrable systems and

Umbral Moonshine and the Niemeier Lattices

\mathcal{N}=2

Non-Perturbative Topological Strings and Conformal Blocks

gauge systems in four dimensions observed by Nekrasov and Shatashvili.

Deformations of Lifshitz holography

In this paper, we relate umbral moonshine to the Niemeier lattices - the 23 even unimodular positive-definite lattices of rank 24 with non-trivial root systems. To each Niemeier lattice, we attach a finite group by considering a naturally defined quotient of the lattice automorphism group, and for each conjugacy class of each of these groups, we identify a vector-valued mock modular form whose components coincide with mock theta functions of Ramanujan in many cases. This leads to the umbral moonshine conjecture, stating that an infinite-dimensional module is assigned to each of the Niemeier lattices in such a way that the associated graded trace functions are mock modular forms of a distinguished nature. These constructions and conjectures extend those of our earlier paper and in particular include the Mathieu moonshine observed by Eguchi, Ooguri and Tachikawa as a special case. Our analysis also highlights a correspondence between genus zero groups and Niemeier lattices. As a part of this relation, we recognise the Coxeter numbers of Niemeier root systems with a type A component as exactly those levels for which the corresponding classical modular curve has genus zero.AMS subject classification11F22; 11F37; 11F46; 11F50; 20C34; 20C35

Mathieu moonshine and \mathcal{N}=2 string compactifications

We give a non-perturbative completion of a class of closed topological string theories in terms of building blocks of dual open strings. In the specific case where the open string is given by a matrix model these blocks correspond to a choice of integration contour. We then apply this definition to the AGT setup where the dual matrix model has logarithmic potential and is conjecturally equivalent to Liouville conformal field theory. By studying the natural contours of these matrix integrals and their monodromy properties, we propose a precise map between topological string blocks and Liouville conformal blocks. Remarkably, this description makes use of the light-cone diagrams of closed string field theory, where the critical points of the matrix potential correspond to string interaction points.

Elliptic Genera and 3d Gravity

The simplest gravity duals for quantum critical theories with z = 2 ‘Lifshitz’ scale invariance admit a marginally relevant deformation. Generic black holes in the bulk describe the field theory with a dynamically generated momentum scale Λ as well as finite temperature T. We describe the thermodynamics of these black holes in the quantum critical regime where T ≫ Λ2. The deformation changes the asymptotics of the spacetime mildly and leads to intricate UV sensitivities of the theory which we control perturbatively in Λ2/T .

Mock Modular Mathieu Moonshine Modules

A bstractThere is a ‘Mathieu moonshine’ relating the elliptic genus of K3 to the sporadic group M24. Here, we give evidence that this moonshine extends to part of the web of dualities connecting heterotic strings compactified on K3 × T2 to type IIA strings compactified on Calabi-Yau threefolds. We demonstrate that dimensions of M24 representations govern the new supersymmetric index of the heterotic compactifications, and appear in the Gromov-Witten invariants of the dual Calabi-Yau threefolds, which are elliptic fibrations over the Hirzebruch surfaces

More bubbling solutions

{{\mathbb{F}}_n}

Positivity of energy for asymptotically locally AdS spacetimes

.

Rademacher Sums and Rademacher Series

We describe general constraints on the elliptic genus of a 2d supersymmetric conformal field theory which has a gravity dual with large radius in Planck units. We give examples of theories which do and do not satisfy the bounds we derive, by describing the elliptic genera of symmetric product orbifolds of K3, product manifolds, certain simple families of Calabi–Yau hypersurfaces, and symmetric products of the “Monster CFT”. We discuss the distinction between theories with supergravity duals and those whose duals have strings at the scale set by the AdS curvature. Under natural assumptions, we attempt to quantify the fraction of (2,2) supersymmetric conformal theories which admit a weakly curved gravity description, at large central charge.