Quantum Effects on the Deflection of Light and the Gauss-Bonnet Theorem
  In this letter we apply the Gauss--Bonnet theorem (GB) to calculate the deflection angle by a quantum corrected Schwarzschild black hole in the weak limit approximation. In particular we calculate the light deflection by two types of quantum corrected black holes: the renormalization group improved Schwarzschild solution and the quantum corrected Schwarzschild solution in Bohmian quantum mechanics. We start from the corresponding optical metrics to use then the GB theorem and calculate the Gaussian curvature in both cases. We calculate the leading terms of the deflection angle and show that quantum corrections modifies the deflection angle in both solutions. Finally by performing geodesics calculations we show that GB method gives exact results in leading order terms. 
Kimet Jusufi
gr-qc