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Article
Open AccessDefects, nested instantons and comet-shaped quivers
We introduce and study a surface defect in four-dimensional gauge theories supporting nested instantons with respect to the parabolic reduction of the gauge group at the defect. This is engineered from a ...
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Article
Open AccessReal topological string amplitudes
We discuss the physical superstring correlation functions in type I theory (or equivalently type II with orientifold) that compute real topological string amplitudes. We consider the correlator corresponding to h...
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Article
Four-Dimensional Yang–Mills Theory as a Deformation of Topological BF Theory
The classical action for pure Yang–Mills gauge theory can be formulated as a deformation of the topological BF theory where, beside the two-form field B, one has to add one extra-field η given by a one-form which...
