Orbifolds of M-Theory and Type II String Theories in Two Dimensions

We consider several orbifold compactifications of M-theory and their corresponding type II duals in two space-time dimensions. In particular, we show that while the orbifold compactification of M-theory on T/J9 is dual to the orbifold compactification of type IIB string theory on T/I8, the same orbifold T /I8 of type IIA string theory is dual to Mtheory compactified on a smooth product manifold K3 × T. Similarly, while the orbifold compactification of M-theory on (K3 × T)/σ · J5 is dual to the orbifold compactification of type IIB string theory on (K3 × T)/σ ·I4, the same orbifold of type IIA string theory is dual to the orbifold T × (K3 × S)/σ · J1 of M-theory. The spectrum of various orbifold compactifications of M-theory and type II string theories on both sides are compared giving evidence in favor of these duality conjectures. We also comment on a connection between Dasgupta-Mukhi-Witten conjecture and Dabholkar-Park-Sen conjecture for the six-dimensional orbifold models of type IIB string theory and M-theory. E-mail address: [email protected]