Generalized Pions in Dense QCD

TL;DR

This paper analyzes the properties of generalized pions, Goldstone modes in dense QCD's CFL phase, providing exact calculations of their form factors, masses, and decay constants, and confirming their consistency with axial symmetry constraints.

Contribution

It offers the first exact evaluation of form factors, masses, and decay constants of generalized pions in the CFL phase of dense QCD, confirming their theoretical consistency.

Findings

Exact form factor, mass, and decay constant calculations for generalized pions.

Validation of Goldstone modes satisfying axial-Ward-identity.

Goldstone modes' properties derived in weak coupling regime.

Abstract

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-Ward-identity, constraining the mass of the Goldstone modes in the CFL phase.