Title:
A counterexample to the "a-theorem"
Abstract:
Zamalodchikov's c-theorem in 2d states that the central charge c
decreases along the renormalization group flow, and the search for its
four-dimensional analogue led to the formulation of
the conjectural "a-theorem". I describe a class of strongly-coupled
CFTs which violates this "a-theorem".
Title:
Argyres-Seiberg duality and the Higgs branch
Abstract:
We demonstrate the agreement between the Higgs branches of two
N=2 theories proposed by Argyres and Seiberg to be S-dual.
In mathematical terms, we demonstrate the equivalence between
a hyperkaehler quotient of a linear space and another hyperkaehler quotient
involving the minimal nilpotent orbit of E_6.