Celestial fields on the string and the Schwarzian action

TL;DR

This paper introduces a celestial field formalism for classical strings in AdS3, leading to a straightforward derivation of the Schwarzian action for near-AdS2 configurations, connecting string dynamics with boundary time fields.

Contribution

It presents a novel celestial field approach to describe string motion in AdS3 and derives the Schwarzian action for near-AdS2 embeddings.

Findings

Celestial fields correspond to boundary null rays in AdS3.

The formalism simplifies derivation of the Schwarzian action.

Provides a new perspective on string dynamics in AdS spacetime.

Abstract

This paper describes the motion of a classical Nambu-Goto string in three-dimensional anti-de Sitter spacetime in terms of two `celestial' fields on the worldsheet. The fields correspond to retarded and advanced boundary times at which null rays emanating from the string reach the boundary. The formalism allows for a simple derivation of the Schwarzian action for near-AdS2 embeddings.