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Fundamental Plasmid Strings and Black Rings

Jose J. Blanco-Pillado, Roberto Emparan, Alberto Iglesias

TL;DR

The paper develops a dual picture linking semiclassical circular loops of fundamental strings, or plasmid strings, to rotating dipole black rings in supergravity. By constructing explicit classical and quantum states, it shows that the mass, radius, and angular momenta of the string loops match the five-dimensional dipole-ring solutions, and that the microscopic degeneracy reproduces the supergravity entropy scaling $S\sim\sqrt{n_w J_{12}}$, with a tubular two-angular-momentum generalization $S\sim\sqrt{n_w J_{12}-|J_{34}|}$ when a second angular momentum is present. In the five- and higher-dimensional gravity descriptions, thin-ring limits yield the same leading parameters $M\approx 2R n_w/\alpha'$ and $J_{12}\approx R^2 n_w/\alpha'$, while higher-derivative corrections imply a stretched-horizon entropy that matches the microscopic count. The work also interprets string decay as ergoregion superradiance and extends the correspondence to tubular (supertube) configurations, offering a window into the microphysics of neutral black rings and potential connections to fuzzball-type pictures in quantum gravity.

Abstract

We construct excited states of fundamental strings that admit a semiclassical description as rotating circular loops of string. We identify them with the supergravity solutions for rotating dipole rings. The identification involves a precise match of the mass, radius and angular momentum of the two systems. Moreover, the degeneracy of the string state reproduces the parametric dependence of the entropy in the supergravity description. When the solutions possess two macroscopic angular momenta, they are better described as toroidal configurations (tubular loops) instead of loops of string. We argue that the decay of the string state can be interpreted as superradiant emission of quanta from the ergoregion of the rotating ring.

Fundamental Plasmid Strings and Black Rings

TL;DR

The paper develops a dual picture linking semiclassical circular loops of fundamental strings, or plasmid strings, to rotating dipole black rings in supergravity. By constructing explicit classical and quantum states, it shows that the mass, radius, and angular momenta of the string loops match the five-dimensional dipole-ring solutions, and that the microscopic degeneracy reproduces the supergravity entropy scaling , with a tubular two-angular-momentum generalization when a second angular momentum is present. In the five- and higher-dimensional gravity descriptions, thin-ring limits yield the same leading parameters and , while higher-derivative corrections imply a stretched-horizon entropy that matches the microscopic count. The work also interprets string decay as ergoregion superradiance and extends the correspondence to tubular (supertube) configurations, offering a window into the microphysics of neutral black rings and potential connections to fuzzball-type pictures in quantum gravity.

Abstract

We construct excited states of fundamental strings that admit a semiclassical description as rotating circular loops of string. We identify them with the supergravity solutions for rotating dipole rings. The identification involves a precise match of the mass, radius and angular momentum of the two systems. Moreover, the degeneracy of the string state reproduces the parametric dependence of the entropy in the supergravity description. When the solutions possess two macroscopic angular momenta, they are better described as toroidal configurations (tubular loops) instead of loops of string. We argue that the decay of the string state can be interpreted as superradiant emission of quanta from the ergoregion of the rotating ring.

Paper Structure

This paper contains 14 sections, 76 equations, 2 figures.

Table of Contents

  1. Introduction
  2. Classical Fundamental Plasmid String
  3. Microscopic description of a circular string loop
  4. Fixing the gauge and solving the constraints
  5. The state
  6. Degeneracies
  7. Right-movers with angular momentum
  8. Supergravity solution for a rotating loop of fundamental string
  9. The 5D solution and its physical parameters
  10. $D\geq 6$
  11. Entropy
  12. Second angular momentum: Tubular loops
  13. String decay by superradiant emission
  14. Discussion

Figures (2)

  • Figure 1: Plasmid string, describing a rotating loop of string. The rotation of the ring corresponds to the helical advance of the string. For a generic rotating string loop, the profile of the string oscillations is not a circular helix but a wiggly structure.
  • Figure 2: Tubular loop: when the radius of the helix oscillations is macroscopically large, instead of a loop of string we obtain a toroidal tube (for large $n_w$ the string is very uniformly spread on the tube; in the picture $n_w=7$). It rotates in the two circles of the torus, with $|J_{34}|\leq n_w J_{12}$.