Math @ Duke

Publications [#9652] of Eric Sharpe
Preprints
 Eric Sharpe, Discrete Torsion
, preprint 2000 [hepth/0008154]
(last updated on 2000/08/22)
Abstract: In this article we explain discrete torsion. Put simply,
discrete torsion is the choice of orbifold group action on
the B field. We derive the classification H^2(G, U(1)),
we derive the twisted sector phases appearing in string
loop partition functions, we derive M. Douglas's description
of discrete torsion for Dbranes in terms of a projective
representation of the orbifold group, and we outline how
the results of VafaWitten fit into this framework. In
addition, we discover some new degrees of freedom that
appear in describing orbifold group actions on B fields, in
addition to those classified by H^2(G, U(1)), and explain
how these new degrees of freedom appear in terms of twisted
sector contributions to partition functions and in terms of
orbifold group actions on Dbrane worldvolumes. This paper
represents a technically simplified version of prior papers
by the author on discrete torsion. We repeat here
technically simplified versions of results from those
papers, and have included some new material.


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