On the sqrt{2} puzzle in AdS_2/CFT_1
  In this letter we analyze the Hamiltonian formulation of the Jackiw-Teitelboim model of 2D gravity and calculate the central charge associated with the asymptotic symmetries, taking care of boundary terms. For black hole solutions, we show that there is no sqrt{2} discrepancy between the thermodynamical entropy and the statistical one obtained via Cardy's formula. 
G. Catelani, L. Vanzo