Higgs mode and universal dynamics near quantum criticality

Abstract:

The Higgs mode is a ubiquitous collective excitation in condensed matter systems with broken continuous symmetry.  It plays a role analogous to the Higgs boson in particle physics.  Its detection is a valuable test of the corresponding field theory, and its mass gap measures the proximity to a quantum critical point. However, since the Higgs mode can decay into low energy Goldstone modes, its experimental visibility has been questioned. In this talk, I will show that the visibility of the Higgs mode depends on the symmetry of the measured susceptibility. I will also present an analysis of the evolution of the Higgs mode upon approach to the Wilson-Fisher fixed point in 2+1 dimensions and demonstrate that the Higgs mode survives as a universal resonance in the scalar susceptibility arbitrarily close to the quantum critical point. I will discuss the implications of these results for experiments on lattice Bose condensates and thin film superconductors near the Mott insulator to superfluid transition.