Physical Fock space of tensionless strings

TL;DR

This paper investigates the structure of the physical Fock space in tensionless string theory with perimeter action, revealing a spectrum of massless states classified by Wigner's little group, with null states at low excitation levels.

Contribution

It provides a detailed classification of the Fock space states in tensionless strings and identifies null states at the first two excitation levels.

Findings

Ground state contains infinite massless helicity fields

Excitation levels realize continuous spin representations

First two excitation levels are null states

Abstract

We study the physical Fock space of the tensionless string theory with perimeter action which has pure massless spectrum. The states are classified by the Wigner's little group for massless particles. The ground state contains infinite many massless fields of fixed helicity, the excitation levels realize CSR representations. We demonstrate that the first and the second excitation levels are physical null states.