Gauss-Bonnet correction to theR-current correlator inN=4theory at strong coupling

We consider higher-curvature corrections to the $R$-current correlator by studying the propagation of a $U(1)$ field in Einstein--Gauss--Bonnet gravity with a negative cosmological constant. We numerically solve the Maxwell equations and plot an $R$-current spectral function with lightlike momenta, which contains pivotal information of thermal photon emission. We also analytically compute the $R$-current correlator in the long-distance limit by using the holographic membrane paradigm. In the high-energy regime, the inelastic scattering between $R$-current and gauge theory plasma is expected to happen, which will reveal the structure of the plasma at strong coupling. It turns out that the Gauss--Bonnet correction effectively rescales all physical quantities considered here by some functions of the Gauss--Bonnet coefficient. In particular, the Gauss--Bonnet terms will enhance or weaken signatures calculated here in accordance with the sign of the Gauss--Bonnet coefficient.