Strings vs Spins on the Null Orbifold
Abstract
We study the null orbifold singularity in 2+1 d flat space higher spin theory as well as string theory. Using the Chern-Simons formulation of 2+1 d Einstein gravity, we first observe that despite the singular nature of this geometry, the eigenvalues of its Chern-Simons holonomy are trivial. Next, we construct a resolution of the singularity in higher spin theory: a Kundt spacetime with vanishing scalar curvature invariants. We also point out that the UV divergences previously observed in the 2-to-2 tachyon tree level string amplitude on the null orbifold do not arise in the $\alpha^\prime\to \infty$ limit. We find all the divergences of the amplitude and demonstrate that the ones remaining in the tensionless limit are physical IR-type divergences. We conclude with a discussion on the meaning and limitations of higher spin (cosmological) singularity resolution and its potential connection to string theory.
- Publication:
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arXiv e-prints
- Pub Date:
- August 2014
- DOI:
- 10.48550/arXiv.1408.3296
- arXiv:
- arXiv:1408.3296
- Bibcode:
- 2014arXiv1408.3296S
- Keywords:
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- High Energy Physics - Theory;
- General Relativity and Quantum Cosmology
- E-Print:
- 27 pages, 5 figures, v2: comments about boundary conditions added, strengthening the conclusion