N=2 Strings on Orbifolds

TL;DR

This paper investigates the properties of closed N=2 strings on specific orbifolds, analyzing their partition functions, cohomology, amplitudes, and D-brane backgrounds to deepen understanding of their quantum structure.

Contribution

It provides explicit calculations of partition functions, cohomology, and amplitudes for N=2 strings on orbifolds, including the effects of D-branes, which are novel contributions.

Findings

Partition function is modular invariant.

Explicit vertex operators are constructed.

Twist state correlators with D-branes are computed.

Abstract

We study closed N=2 strings on orbifolds of the form T^4/Z_2 and C^2/Z_2. We compute the torus partition function and prove its modular invariance. We analyse the BRST cohomology of the theory, construct the vertex operators, and compute three and four point amplitudes of twisted and untwisted states. We introduce a background of D-branes, and compute twist states correlators.