Workshop on Integrable Field Theories, Solitons and Duality. PROCEEDINGS Monodromy, Duality and Integrability of Two Dimensional String Effective Action Ashok Das∗†, J. Maharana‡ and A. Melikyan† † Department of Physics and Astronomy University of Rochester, Rochester, NY 14627-0171, USA. hep2001 E-mail:
[email protected],
[email protected] ‡ Institute of Physics Bhubaneswar -751005, India E-mail:
[email protected] Abstract: In this talk, we show how the monodromy matrix, , can be constructed for M the two dimensional tree level string effective action. The pole structure of is derived c M using its factorizability property. It is shown that the monodromy matrix transforms non-trivially under the non-compact T-duality group, which leaves the effectivec action invariant and this can be used to construct the monodromy matrix for more complicated backgrounds starting from simpler ones. We construct, explicitly, for the exactly M solvable Nappi-Witten model, both when B =0andB= 0, where these ideas can be 6 c directly checked. 1. Introduction The field theories in two space-time dimensions have attracted considerable attention over the past few decades. They possess a variety of interesting features. Some of these field theories, capture several salient characteristics of four dimensional theories and, therefore, such two dimensional models are used as theoretical laboratories. Moreover, the nonper- turbative properties of field theories are much simpler to study in two dimensional models. There are classes of two dimensional theories which are endowed with a rich symmetry structure: integrable models [1] and conformal field theories [2, 3] belong to this special ∗Speaker. Workshop on Integrable Field Theories, Solitons and Duality.