Chennai Mathematical Institute


Subject : Physics
Date and Time : Wednesday, 21 September 2022, 2.00 pm
Venue : Lecture Hall 1 (Hybrid mode)
Penrose Limits, PP-wave in Supergravity Backgrounds and their non-Abelian T-duals

Sourav Roychowdhury
IACS, Kolkata.


In the first part of the talk, we consider various type-IIA supergravity solutions that originated by applying non-Abelian T-duality on well-known type-IIB supergravity backgrounds. Abelian T-duality is an exact symmetry of the string theory of all orders of α′. However, non- Abelian T-duality works as a solution-generating technique at the supergravity level. We present the non-Abelian T-dual supergravity solutions originating from AdS5× S5 geometry, Klebanov- Witten geometry, Klebanov-Tseytlin background and the D1−D5 system, where T-duality acts on an appropriate non-Abelian isometry group SU(2). We study the Penrose limits in these T-dual backgrounds. In most cases, the Penrose limits lead to pp-wave geometries in the neighbourhood of appropriate null geodesics. The quantization of closed string on the resulting pp-wave has also been discussed. We also study the supersymmetry analysis of these type-IIA pp-wave geometries and draw some comments on the dual gauge theory.

In the remaining part of the talk, we discuss some aspects of Double Field Theory (DFT). Double Field Theory is constructed to incorporate T-duality as a manifested symmetry of string theory. In the talk we introduce the relaxed version of the generalized Kerr-Schild ansatz (GKSA) in the context of heterotic DFT to study perturbations of the fundamental fields in the theory. We also discuss the classical double copy correspondence in this framework.