  We show how to exactly calculate the refined indices of N=4 U(1) times U(N)
supersymmetric quiver quantum mechanics in the Coulomb branch by using the
localization technique. The Coulomb branch localization is discussed from the
viewpoint of both non-linear and gauged linear sigma models. A classification
of fixed points in the Coulomb branch differs from one in the Higgs branch, but
the derived indices completely agree with the results which were obtained by
the localization in the Higgs branch. In the Coulomb branch localization, the
refined indices can be written as a summation over different sets of the
Coulomb branch fixed points. We also discuss a space-time picture of the fixed
points in the Coulomb branch.

High Energy Physics - Theory