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arXiv · hep-th/9612108

Point-like Instantons and the Spin(32)/Z2 Heterotic String

Paul S. Aspinwall
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Abstract

We consider heterotic string theories compactified on a K3 surface which lead to an unbroken perturbative gauge group of Spin(32)/Z2. All solutions obtained are combinations of two types of point-like instanton --- one ``simple type'' as discovered by Witten and a new type associated to the ``generalized second Stiefel-Whitney class'' as introduced by Berkooz et al. The new type of instanton is associated to an enhancement of the gauge symmetry by Sp(4) and the addition of a massless tensor supermultiplet. It is shown that if four simple instantons coalesce at an orbifold point in the K3 surface then a massless tensor field appears which may be used to interpolate between the two types of instanton. By allowing various combinations of point-like instantons to coalesce, large gauge groups (e.g., rank 128) with many massless tensor supermultiplets result. The analysis is done in terms of F-theory.

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Paul S. Aspinwall. 1997-02-04. Point-like Instantons and the Spin(32)/Z2 Heterotic String. https://doi.org/10.1016/s0550-3213(97)00232-0

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