Tensionless Strings: A perspective from the worldsheet
We revisit the construction of the tensionless limit of closed bosonic string theory in the covariant formulation in the light of Galilean conformal symmetry that rises as the residual gauge symmetry on the tensionless worldsheet. We relate the analysis of the fundamentally tensionless theory to the tensionless limit that is viewed as a contraction of worldsheet coordinates. We are able to naively see the connection to massless higher spin states. We extend this analysis to the closed superstring to obtain the Super Gallilean Conformal Algebra. Analysis of the quantum regime uncovers interesting physics. The degrees of freedom that appear in the tensionless string are fundamentally different from the usual string states. Through a Bogoliubov transformation on the worldsheet, we link the tensionless vacuum to the usual tensile vacuum. As an application, we discuss how our analysis can be connected to Hagedorn, Physics, Left-Right Entanglement Entropy and Boundary states.