PAPER / ARXIV:2609.10272
Ilarion V. Melnikov , Ruben Minasian
RESUMO
We discuss orbifold compactifications of the type II string, where the orbifold combines a free action on a base manifold and the $(-1)^{\boldsymbol{F}_{\text{L}}}$ symmetry which acts by -1 on left-moving Ramond sectors. Such backgrounds can preserve minimal supersymmetry and lift to M-theory compactification on smooth unorientable manifolds.
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