what does it mean when they say the Gauge "Sector" of SM?
what other sectors are there?
Re: what does it mean when they say the Gauge "Sector" of SM?
I guess they (who are they?) mean the gauge field sector, i.e. the terms in the Lagrangian where only the field strength tensors appear as F² (for the electro-weak gauge fields and the gluon fields).
The other sectors would be
a) the fermionic sectors (where we have the kinetic terms of the fermions plus the interaction with the gauge field)
b) the Higgs sector (where we have the Higgs kinetic term, teh mass term, plus its couplings to all other fields)
Separate names with a comma.