Extended structures and new infinite-dimensional hidden symmetries for the Einstein?Maxwell-dilaton-axion theory with multiple vector fields

Abstract

A so-called extended elliptical-complex (EEC) function method is proposed and used to further study the Einstein–Maxwell-dilaton-axion theory with p vector fields (EMDA-p theory, for brevity) for \( p = 1,2,\ldots \). An Ernst-like \(2^{k+1}\times 2^{k+1}(k = [(p+1)/2])\) matrix EEC potential is introduced and the motion equations of the stationary axisymmetric EMDA-p theory are written as a so-called Hauser–Ernst-like self-dual relation for the EEC matrix potential. In particular, for the EMDA-2 theory, two Hauser–Ernst-type EEC linear systems are established and based on their solutions some new parametrized symmetry transformations are explicitly constructed. These hidden symmetries are verified to constitute an infinite-dimensional Lie algebra, which is the semidirect product of the Kac–Moody algebra \(su(2,2)\otimes R(t,t^{-1})\) and Virasoro algebra (without centre charges). These results show that the studied EMDA-p theories possess very rich symmetry structures and the EEC function method is necessary and effective.