Fluctuation modes in color-superconductors

Fluctuation modes in multi-gap superonductivity and theory of spontaneous symmetry breaing

We discuss the Nambu-Goldstone boson and the WardTakahashi identity in a system with spontaneous symmetry breaking. We give a formula for the Nambu-Goldstone boson for a general transformation group G. The Ward-Takahashi identity is modified in the presence of the Nambu-Goldstone boson. We apply this theory to examine low-excitation modes in superconductors. In a multi-gap superconductor, the m...

Collective Modes in High-Temperature Superconductors

The role of collective modes in various experiments on the cuprates is investigated. We calculate the neutron scattering, photoemission (ARPES), and Raman scattering intensities below Tc within the fluctuation-exchange (FLEX) approximation for the two-dimensional Hubbard model. It is shown that the large peak in the dynamical spin susceptibility arises from a weakly damped spin-density-wave col...

Non-Abelian Strings in High Density QCD: Zero Modes and Interactions

The most fundamental strings in high density color superconductivity are the non-Abelian semi-superfluid strings which have color gauge flux tube but behave as superfluid vortices in the energetic point of view. We show that in addition to the usual translational zero modes, these vortices have normalizable orientational zero modes in the internal space, associated with the color-flavor locking...

Generalized Pions in Dense QCD

QCD superconductors in the color-flavor-locked (CFL) phase sustain light Goldstone modes (that will be referred to as generalized pions) that can be described as pairs of particle and/or hole excitations around a gapped Fermi surface. In weak coupling and to leading logarithm accuracy, their form factor, mass and decay constant can be evaluated exactly. These modes are found to satisfy an axial...

Apparent Universal Behavior of Fluctuation-Induced Diamagnetism in Superconductors