Higher-derivative heterotic Double Field Theory and classical double copy

The generalized Kerr-Schild ansatz (GKSA) is a powerful tool for constructing exact solutions in Double Field Theory (DFT). In this paper we focus the heterotic formulation of DFT, considering up to four-derivative terms action principle, while field content perturbed by GKSA. We study inclusion version Green-Schwarz mechanism setup, order reproduce low energy effective supergravity upon parametrization. This formalism reproduces higher-derivative background where metric tensor and Kalb-Ramond are pair null vectors. Next contributions classical double copy structure. After suitable identification vectors with $U(1)$ gauge fields, dynamics given Maxwell equations plus higher derivative corrections agreement KLT relation.