Topology of black hole phase transition in JT gravity

Abstract: We present a JT gravity setup coupled with $U(1)$ and $SU(2)$ Yang-Mills fields in two dimensions that reveals the onset of a small black hole to large black hole phase transition at finite chemical potential(s). We identify these black hole solutions as topological defects in the thermodynamic phase space and calculate the associated topological numbers following the standard procedure. We confirm the robustness of our model by estimating perturbative corrections to the bulk free energy at an arbitrary order in the Yang-Mills coupling. We also construct the Schwarzian for the boundary theory using the 2D gravitational action in the bulk and comment on the dual SYK like model where similar observations can be made.