On the Consistency of Null Strings Literature: The Tale of an Overlooked Symmetry

TL;DR

This paper reveals a previously overlooked local symmetry in null string theory, leading to a correction in the count of physical degrees of freedom from D-2 to D-3, and calls for a revision of existing literature.

Contribution

It identifies a new local symmetry in null strings and corrects the degrees of freedom count, challenging prior assumptions in the field.

Findings

Null string action has a hidden local symmetry.

Correct accounting reduces degrees of freedom from D-2 to D-3.

Previous literature over-counted states due to overlooked symmetry.

Abstract

We observe that the null string action possesses a previously overlooked local symmetry. By correctly accounting for this symmetry, we show that the number of physical propagating degrees of freedom of null strings in $D$ dimensional target space is $D-3$, in contrast to $D-2$ that one finds in the literature. Overlooking this symmetry has led to an unphysical over-counting of states, rendering the null string analyses inconsistent. Thus, our observation calls for a thorough revision of all statements and results in the null string literature.