Two-dimensional string theories provide rich laboratories for investigating fundamental aspects of string theory and holographic duality. In this talk, I will study the S-matrix elements of closed strings in the 2D type 0B string theory from the worldsheet perspective.
First, at the level of string perturbation theory, I will describe the computation of the tree level 3- and 4-point scattering amplitudes and show that they agree with the conjectured dual matrix quantum mechanics (MQM).
Second, I will describe non-perturbative effects mediated by D-instantons on closed string scattering amplitudes. In particular, I will discuss the contribution from a pair of a D-instanton and an anti-D-instanton to the closed string reflection amplitude and show that it agrees with the corresponding non-perturbative corrections due to the tunneling of fermions in the proposed dual MQM.
These results provide strong evidence for the conjectured exact holographic duality between the type 0B string theory and the type 0B matrix quantum mechanics.