The Worldsheet Perspective of T-duality Symmetry in String Theory

Understand

The purpose of this article is to present a pedagogical review of T-dualityin in string theory.

• The evolution of the closed string is envisaged on the worldsheet in the presence of its massless excitations.
• The duality symmetry is studied when some of the spacial coordinates are compactified on d-dimensional torus, $T^d$.
• The known results are reviewed to elucidate that equations of motion for the compact coordinates are $O(d,d)$ covariant, $d$ being the number of compact directions.