arXiv2025
We study the impact of higher-derivative corrections from Effective Field Theory on the quasinormal mode spectrum of Reissner-Nordström black holes. While previous work has explored corrections to Schwarzschild and Kerr black holes - typically using small-rotation approximations - a comprehensive analysis near extremality remains lacking. We focus on Reissner-Nordström black holes as a tractable model admitting an extremal limit, enabling investigation of the effect of these corrections on the so-called zero damped modes, which dominate in this regime. Specifically, we derive a corrected Moncrief equation governing quasinormal modes and present both analytic and numerical results for the corrected frequencies. This work also offers the first explicit test of the recently proposed "Quasinormal Mode Causality" bound arXiv:2401.05524, which constrains Effective Field Theory coefficients by requiring that quasinormal mode lifetimes do not increase measurably under ultraviolet-complete Effective Field Theory corrections. Using Standard Model contributions - particularly those arising from integrating out the electron - we verify that this bound holds. Our results provide new insights into the interplay between Effective Field Theory, extremal black hole dynamics, and causality in gravitational theories.