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Comments on Open-String Orbifolds with a Non-Vanishing B_{ab}

Carlo Angelantonj
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Abstract

We study the effect of a non-vanishing flux for the NS-NS antisymmetric tensor in open-string orbifolds. As in toroidal models, the total dimension of the Chan-Paton gauge group is reduced proportionally to the rank of $B_{ab}$, both on D9 and on D5-branes, while the Moebius amplitude involves some signs that, in the $Z_2$ case, allow one to connect continuously ${\rm U} (n)$ groups to $Sp(n) \otimes Sp(n)$ groups on each set of D-branes. In this case, non-universal couplings between twisted scalars and gauge vectors arise, as demanded by the generalised Green-Schwarz mechanism. We also comment on the role of the NS-NS antisymmetric tensor in a recently proposed type scenario, where supersymmetry is broken on the D-branes, while it is preserved in the bulk.

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Carlo Angelantonj. 1999-10-15. Comments on Open-String Orbifolds with a Non-Vanishing B_{ab}. https://doi.org/10.1016/s0550-3213(99)00662-8

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