
Motivated by the geometric character of spin Hall conductance, the topological invariants of generic superconductivity are discussed based on the Bogoliuvov-de Gennes equation on lattices. They are given by the Chern numbers of degenerate condensate bands for unitary order, which are realizations of Abelian chiral anomalies for non-Abelian connections. The three types of Chern numbers for the $x,y$ and $z$-directions are given by covering degrees of some doubled surfaces around the Dirac monopoles. For nonunitary states, several topological invariants are defined by analyzing the so-called $q$-helicity. Topological origins of the nodal structures of superconducting gaps are also discussed.
An example with a figure and discussions are supplemented
Superconductivity (cond-mat.supr-con), Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), FOS: Physical sciences
Superconductivity (cond-mat.supr-con), Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), FOS: Physical sciences
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