D-branes on Fourfolds with Discrete Torsion

We study D1-branes on the fourfold C/(Z2 × Z2 × Z2), in the presence of discrete torsion. Discrete torsion is incorporated in the gauge theory of the D1-branes by considering a projective representation of the finite group Z2 × Z2 × Z2. The corresponding orbifold is then deformed by perturbing the F-flatness condition of the gauge theory. The moduli space of the resulting gauge theory retains a stable singularity of codimension three. E–mail: [email protected] [Address after 24 Sept, 1999 : Fysikum, Stockholm university, Box 6730, S-113 46, Stockholm, Sweden] E–mail: [email protected]