What is Classical Null String Theory?
Abstract
We revisit the classical definition of a null string in a D-dimensional Minkowski target space and distinguish a consistent partially-gauged Carrollian sigma-model from the null string theory. The Isberg-Lindström-Sundborg-Theodoridis (ILST) action gauges worldsheet diffeomorphisms and the common Weyl rescaling, but not the independent relative rescaling of the temporal and spatial representatives of the intrinsic Carrollian structure, Carroll-Weyl scaling. A physical string theory requires every local change of worldsheet representative to be gauged, therefore, the Carroll-Weyl symmetry should be gauged in a null string theory. In the minimal realization, the corresponding gauging is obstructed at finite tension, whereas at zero tension it yields an additional first-class constraint and the associated identification of physical configurations along its gauge orbits. The description of the null worldsheet as a congruence of null geodesics provides a complementary target-space interpretation of gauging of the Carroll-Weyl scaling. Our analysis thus provides the supplementary requirements that turns the ILST theory into the null string theory.
Related
- Carrollian Worldsheets on Carrollian Targets, When does ILST describe a null string theory?
- Null string holography in AdS from local BRST descent
- Null String Holography, Null Strings Probe Projective Boundary of Their Target Spaces
- Double Copy from the Flipped Null String
- Null Geodesics in the Reissner-Nordström Black Hole Spacetime Pierced by a Cosmic String
BibTeX
@misc{sheikhjabbari2026what,
title = {{What is Classical Null String Theory?}},
author = {M. M. Sheikh-Jabbari and H. Yavartanoo},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.04844},
eprint = {2609.04844},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.04844},
}
RIS
TY - UNPB
TI - What is Classical Null String Theory?
AU - M. M. Sheikh-Jabbari
AU - H. Yavartanoo
PY - 2026
DA - 2026/09/04
PB - arXiv
DO - 10.48550/arxiv.2609.04844
UR - https://arxiv.org/abs/2609.04844
AB - We revisit the classical definition of a null string in a D-dimensional Minkowski target space and distinguish a consistent partially-gauged Carrollian sigma-model from the null string theory. The Isberg-Lindström-Sundborg-Theodoridis (ILST) action gauges worldsheet diffeomorphisms and the common Weyl rescaling, but not the independent relative rescaling of the temporal and spatial representatives of the intrinsic Carrollian structure, Carroll-Weyl scaling. A physical string theory requires every local change of worldsheet representative to be gauged, therefore, the Carroll-Weyl symmetry should be gauged in a null string theory. In the minimal realization, the corresponding gauging is obstructed at finite tension, whereas at zero tension it yields an additional first-class constraint and the associated identification of physical configurations along its gauge orbits. The description of the null worldsheet as a congruence of null geodesics provides a complementary target-space interpretation of gauging of the Carroll-Weyl scaling. Our analysis thus provides the supplementary requirements that turns the ILST theory into the null string theory.
ER -