Conformal invariant strings with extrinsic curvature action

TL;DR

This paper introduces a tensionless string theory based solely on extrinsic curvature, which is quantized as a conformal field theory in 13 dimensions with a massless spectrum of particles of all spins.

Contribution

It presents a solvable, quantized, high-derivative conformal string model with no conformal anomaly in 13D, proposing a potential link to an unbroken phase of standard string theory.

Findings

No conformal anomaly in 13-dimensional spacetime.

All particles are massless regardless of spin.

The theory is a tensionless, extrinsic curvature-based string model.

Abstract

We study a string theory which is exclusively based on extrinsic curvature action. It is a tensionless string theory because the action reduces to perimeter for the flat Wilson loop. We are able to solve and quantize this high-derivative nonlinear two-dimensional conformal field theory. The absence of conformal anomaly in quantum theory requires that the space-time should be 13-dimensional. We have found that all particles, with arbitrary large spin, are massless. This pure massless spectrum is consistent with the tensionless character of the theory and we speculate that it may describe unbroken phase of standard string theory.