Discrete Torsion and Shift Orbifolds

Abstract

In this paper we make two observations related to discrete torsion. First, we observe that an old obscure degree of freedom (momentum/translation shifts) in (symmetric) string orbifolds is related to discrete torsion. We point out how our previous derivation of discrete torsion from orbifold group actions on B fields includes these momentum lattice shift phases, and discuss how they are realized in terms of orbifold group actions on D-branes. Second, we describe the M theory dual of IIA discrete torsion, a duality relation to our knowledge not previously understood. We show that IIA discrete torsion is encoded in analogues of the shift orbifolds above for the M theory C field.

28 pages, LaTeX, 3 figures; v2: references added

References in corpus (3)

• Strings on Orbifold Lines
• String Orbifolds and Quotient Stacks
• Discrete Torsion and Branes in M-theory from Mathematical Viewpoint

Cited by in corpus (5)

• Compactifications of Heterotic Strings on Non-Kahler Complex Manifolds: II
• Decomposition, condensation defects, and fusion
• Quantum symmetries in orbifolds and decomposition
• Notes on discrete torsion in orientifolds
• Flat equivariant gerbes: holonomies and dualities