Large Order Enumerative Geometry, Black Holes and Black Rings

TL;DR

This paper analyzes high-genus Gopakumar-Vafa invariants to study the growth of 5D indices, stable pair invariants, and Donaldson-Thomas invariants, revealing black hole and black ring phase transitions and confirming conjectures about topological free energy growth.

Contribution

It provides a numerical study of invariant growth at large charges, identifying phase transitions and extending formulas for GV invariants, with implications for black hole physics.

Findings

5D index matches black hole entropy below a critical angular momentum m.

Black ring dominance occurs when m exceeds a critical value.

Stable pair invariants exhibit phase transitions and polynomial growth at positive m.

Abstract

Exploiting newly available data on Gopakumar-Vafa invariants at high genus for one-parameter hypergeometric Calabi-Yau threefolds, we study numerically the growth of the 5D indices, stable pair (PT) invariants and rank one Donaldson-Thomas (DT) invariants at large charges. For the 5D index $\Omega_{5D}(d,m)$, below a critical value of the angular momentum $m$, we find perfect agreement with the Bekenstein-Hawking-Wald entropy of rotating 5D BMPV black holes, including the subleading correction from 4-derivative interactions. When $m$ exceeds the critical value, the 5D index is instead dominated by black rings with the smallest possible dipole charge. The stable pair invariant $PT(d,m)$, which is determined by 5D indices, has a similar black ring/hole transition at negative $m$ (now interpreted as the D0-brane charge) but surprisingly exhibits two other phase transitions at positive $m$: first, to a plateau and then to a polynomial growth $\sim m^{2d-1}$. In each phase, we derive an approximate expression for the invariant. Finally, the rank one DT invariant $DT(d,m)$ is similar to $PT(d,m)$ at negative $m$, and then transitions to a phase dominated by D0-branes, with entropy of order $m^{2/3}$. Along the way, we determine the fixed genus, large degree behavior of GV invariants (including the overall $g$-dependent constant), extend it to an approximate formula valid also for large $g$, point out the unreasonable effectiveness of a simple PT/MSW relation, and study the growth of topological free energies at fixed degree, confirming a conjecture of Mari\~no.