Refined Black Hole Ensembles and Topological Strings

TL;DR

This paper formulates a refined version of the OSV conjecture linking refined BPS black hole partition functions to refined topological strings, providing evidence through calculations on local Calabi-Yau geometries and 2D gauge theories.

Contribution

It introduces a refined OSV conjecture involving spin-dependent BPS counts and demonstrates its validity on specific non-compact Calabi-Yau manifolds using 2D TQFT and deformed Yang-Mills theories.

Findings

Refined topological string partition function computed by 2D TQFT.

Refined black hole partition function reduces to (q,t)-deformed 2D Yang-Mills.

Large N limit confirms the factorization into the square of the refined topological string.

Abstract

We formulate a refined version of the Ooguri-Strominger-Vafa (OSV) conjecture. The OSV conjecture that Z_{BH} = |Z_{top}|^2 relates the BPS black hole partition function to the topological string partition function Z_{top}. In the refined conjecture, Z_{BH} is the partition function of BPS black holes counted with spin, or more precisely the protected spin character. Z_{top} becomes the partition function of the refined topological string, which is itself an index. Both the original and the refined conjecture are examples of large N duality in the 't Hooft sense. The refined conjecture applies to non-compact Calabi-Yau manifolds only, so the black holes are really BPS particles with large entropy, of order N^2. The refined OSV conjecture states that the refined BPS partition function has a large N dual which is captured by the refined topological string. We provide evidence that the conjecture holds by studying local Calabi-Yau threefolds consisting of line bundles over a genus g Riemann surface. We show that the refined topological string partition function on these geometries is computed by a two-dimensional TQFT. We also study the refined black hole partition function arising from N D4 branes on the Calabi-Yau, and argue that it reduces to a (q,t)-deformed version of two-dimensional SU(N) Yang-Mills. Finally, we show that in the large N limit this theory factorizes to the square of the refined topological string in accordance with the refined OSV conjecture.