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Search: authors:"S. K. Ashok"

3 papers found.
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Modular and duality properties of surface operators in \( \mathcal{N}={2}^{\star } \) gauge theories

We calculate the instanton partition function of the four-dimensional \( \mathcal{N}={2}^{\star } \) SU(N) gauge theory in the presence of a generic surface operator, using equivariant localization. By analyzing the constraints that arise from S-duality, we show that the effective twisted superpotential, which governs the infrared dynamics of the two-dimensional theory on the ...

Chiral observables and S-duality in \( \mathcal{N} \) = 2⋆ U(N ) gauge theories

We study \( \mathcal{N} \) = 2⋆ theories with gauge group U(N ) and use equivariant localization to calculate the quantum expectation values of the simplest chiral ring elements. These are expressed as an expansion in the mass of the adjoint hypermultiplet, with coefficients given by quasi-modular forms of the S-duality group. Under the action of this group, we construct ...

S-duality, triangle groups and modular anomalies in \( \mathcal{N}=2 \) SQCD

We study \( \mathcal{N}=2 \) superconformal theories with gauge group SU(N ) and 2N fundamental flavours in a locus of the Coulomb branch with a \( {\mathbb{Z}}_N \) symmetry. In this special vacuum, we calculate the prepotential, the dual periods and the period matrix using equivariant localization. When the flavors are massless, we find that the period matrix is completely ...