Tensors from K3 Orientifolds
نویسنده
چکیده
Recently Gimon and Johnson [1] and Dabholkar and Park [2] have constructed Type I theories on K3 orbifolds. The spectra differ from that of Type I on a smooth K3, having extra tensors. We show that the orbifold theories cannot be blown up to smooth K3’s, but rather Z2 orbifold singularities always remain. Douglas’s recent proposal to use D-branes as probes is useful in understanding the geometry. The Z2 singularities are of a new type, with a different orientifold projection from those previously considered. We also find a new world-sheet consistency condition that must be satisfied by orientifold models.
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