text: FIG. 3: The BCSI case with a dispersion linearized around the 
  Fermi surface. Evolution of the diﬀerence of optical integrals 
  in the SCS and the NS with the upper cut-oﬀ ωc Observe 
  that the zero crossing point increases with impurity scattering 
  rate Γ and also the ‘dip’ spreads out with increasing Γ. ∆ = 
  30 meV 
  
  FIG. 2: Distribution functions in four cases (a) BCSI model, 
  where one can see that for ε > 0, SC>NS implying KE in- 
  creases in the SCS. (b) The original MFLI model of Ref. 30, 
  where for ε > 0, SC<NS, implying KE decreases in the SCS. 
  (c) Our version of MFLI model (see text) and (d) the CB 
  model. In both cases, SC>NS, implying KE increases in the 
  SCS. Observe that in the impurity-free CB model there is no 
  jump in n(ǫ) indicating lack of fermionic coherence. This is 
  consistent with ARPES39 
  
  For a constant DOS, ∆W (ωc) = WSC (ωc) − WN S(ωc) 
  is zero at ωc = ∞ and Kubo sum rule reduces to FGT 
  sum rule. In Fig. 3 we plot for this case ∆W (ωc) as a 
  function of the cutoﬀ ωc for diﬀerent Γ′s. The plot shows 
  the two well known features: zero-crossing point is below 
  2∆ in the clean limit Γ << ∆ and is roughly 2Γ in the 
  dirty limit21,40 The magnitude of the ‘dip’ decreases quite 
  rapidly with increasing Γ. Still, there is always a point 
  of zero crossing and ∆W (ωc) at large ωc approaches zero 
  from below. 
  (11) 