A Rindler Road to Carrollian Worldsheets

TL;DR

This paper explores how strings in Rindler spacetimes become tensionless near horizons, revealing a connection between spacetime and worldsheet Carroll limits, and uncovers novel worldsheet structures and symmetries such as BMS algebra.

Contribution

It provides a concrete example of tensionless strings in Rindler backgrounds, demonstrating the emergence of Carrollian structures and novel worldsheet features like folds and segmentation.

Findings

Strings near black hole horizons become tensionless.

A Rindler structure is induced on the string worldsheet.

The BMS algebra emerges from the Virasoro algebra at the horizon.

Abstract

The tensionless limit of string theory has recently been formulated in terms of worldsheet Rindler physics. In this paper, by considering closed strings moving in background Rindler spacetimes, we provide a concrete exemplification of this phenomenon. We first show that strings probing the near-horizon region of a generic non-extremal blackhole become tensionless thereby linking a spacetime Carroll limit to a worldsheet Carroll limit. Then, considering strings in $d$-dimensional Rindler spacetime we find a Rindler structure induced on the worldsheet. Novelties, including folds, appear on the closed string worldsheet pertaining to the formation of the worldsheet horizon. The closed string becomes segmented at these folding points and different segments go into the formation of closed strings in the different Rindler wedges. The Bondi-Metzner-Sachs (BMS) or the Conformal Carroll algebra emerges from the closed string Virasoro algebra as the horizon is hit. Quantum states on these accelerated worldsheets are discussed and we show the formation of boundary states from gluing conditions of the different segments of the accelerated closed string.