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The enhançon and $$N=2$$ gauge theory/gravity RG flows. (English) Zbl 0965.81050
Summary: We study the family of ten dimensional type IIB supergravity solutions corresponding to renormalisation group flows from $$N=4$$ to $$N=2$$ supersymmetric Yang-Mills theory. Part of the solution set corresponds to a submanifold of the Coulomb branch of the gauge theory, and we use a D3-brane probe to uncover details of this physics. At generic places where supergravity is singular, the smooth physics of the probe yields the correct one-loop form of the effective low energy gauge coupling. The probe becomes tensionless on a ring at finite radius. Supergravity flows which end on this “enhancon” ring correspond to the vacua where extra massless degrees of freedom appear in the gauge theory, and the gauge coupling diverges there. We identify an $$\text{SL} (2,\mathbb{Z})$$ duality action on the enhancon ring which relates the special vacua, and comment on the massless dyons within them. We propose that the supergravity solution inside the enhancon ring should be excised, since the probe’s tension is unphysical there.

##### MSC:
 81T18 Feynman diagrams 81T13 Yang-Mills and other gauge theories in quantum field theory 83E30 String and superstring theories in gravitational theory 81T60 Supersymmetric field theories in quantum mechanics
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