Closed String Tachyons on C/ZN

We analyze the condensation of closed string tachyons on the C/Z_N orbifold. We construct the potential for the tachyons up to the quartic interaction term in the large N limit. In this limit there are near marginal tachyons. The quartic coupling for these tachyons is calculated by subtracting from the string theory amplitude for the tachyons, the contributions from the massless exchanges, computed from the effective field theory. We argue that higher point interaction terms are also of the same order in 1/N as the quartic term and are necessary for existence of the minimum of the tachyon potential that is consistent with earlier analysis.