On the Tensionless Limit of Bosonic Strings, Infinite Symmetries and Higher Spins

TL;DR

This paper explores the tensionless limit of bosonic string theory, revealing an infinite spectrum of massless higher-spin fields, the loss of critical dimension, and the emergence of infinite symmetries, with implications for string field theory.

Contribution

It demonstrates that in the tensionless limit, string theory's massive states become massless higher-spin fields and connects open and closed strings through natural constraints.

Findings

Massive states become massless higher-spin fields

Infinite global symmetries emerge in the tensionless limit

Tensionless string field theory decomposes into free higher-spin excitations and an interacting sector

Abstract

In the tensionless limit of string theory on flat background all the massive tower of states gets squeezed to a common zero mass level and the free theory is described by an infinite amount of massless free fields with arbitrary integer high spin. We notice that in this situation the very notion of critical dimension gets lost, the apparency of infinite global symmetries takes place, and the closed tensionless string can be realized as a constrained subsystem of the open one in a natural way. Moreover, we study the tensionless limit of the Witten's cubic sting field theory and find that the theory in such a limit can be represented as an infinite set of free arbitrary higher spin excitations plus an interacting sector involving their zero-modes only.