Generality across pairing symmetries and Dirac or Weyl systems

Investigate how broadly the relation between normal-state subtraction and the vertex-corrected electromagnetic response extends to more general multiband superconductors with different pairing symmetries and to other Dirac and Weyl systems.

Background

The analysis is restricted to a three-dimensional massive-Dirac model with isotropic s-wave pairing and a specified ultraviolet cutoff. Within that setting, the authors demonstrate compatibility between normal-state subtraction and the gauge-invariant response generated by the self-consistent vertex correction.

The broader applicability of this relation to multiband superconductors with other pairing symmetries, as well as to distinct Dirac and Weyl materials or low-energy models, is explicitly posed as an unresolved question. Addressing it would clarify whether the microscopic justification for normal-state subtraction is model-specific or represents a more general property of multiband superconducting response theory.