text: ′′ 
  
  which ﬁts 
  where Θ(x) is the step function. In reality, Σ 
  ARPES in the NS has some angular dependence along the 
  Fermi surface42, but this was ignored for simplicity. This 
  model had gained a lot of attention as it predicted the 
  optical sum in the SCS to be larger than in the NS, i.e., 
  ∆W > 0 at large frequencies. This would be consistent 
  with the experimental ﬁndings in Refs. 8,9 if, indeed, one 
  identiﬁes ∆W measured up to 1eV with ∆WK . 
  
  The rationale for ∆WK > 0 in the original MFLI 
  model has been provided in Ref. 30. They argued that 
  this is closely linked to the absence of quasiparticle peaks 
  in the NS and their restoration in the SCS state because 
  the phase space for quasiparticle scattering at low ener- 
  gies is smaller in a superconductor than in a normal state.  We will show below that the sign of ∆W in the MFLI 
  model actually depends on how the normal state results 
  are extended to the superconducting state and, moreover, 
  will argue that ∆WK is actually negative if the extension 
  is done such that at α = 0 the results are consistent with 