Abstract:
We analyze the D-branes of a type-IIB string theory on an
orbifold singularity including the possibility of discrete
torsion following the work of Douglas et al. First we prove
some general results about the moduli space of a point
associated to the ``regular representation'' of the
orbifold group. This includes some analysis of the
``wrapped branes'' which necessarily appear when the
orbifold singularity is not isolated. Next we analyze the
stringy homology of the orbifold using the McKay
correspondence and the relationship between K-theory and
homology. We find that discrete torsion and torsion in this
stringy homology are closely-related concepts but that they
differ in general. Lastly we question to what extent the D-
1 brane may be thought of as being dual to a string.