eta issue answer based on Arjan comment

Response_Letter/Response_Letter.tex

@@ -90,11 +90,17 @@ We look forward to hearing from you.
 	\item 
 	{In Section III the authors mention that the infinitesimal eta is put to 0. 
 	This is physically incorrect. 
-	eta is a positive infinitesimal and cannot be just put to zero. Numerically it has been shown that indeed the self energy becomes discontinuous by doing so. 
+	eta is a positive infinitesimal and cannot be just put to zero. 
+	Numerically it has been shown that indeed the self energy becomes discontinuous by doing so. 
 	This is the main reason for the low quality rating. }
 	\\
-	\alert{Titou: I don't agree with this.}
-	
+	\alert{Physically, $\eta$ ensures the correct time ordering when passing from $(t-t')$ to $\omega$ by a Fourier transform.
+	It is an infinitesimal which should be put to zero at the very end of the calculation.
+	In practice, this is not possible as one would have to solve everything analytically. 
+	Therefore, one has to make a choice: set it equal to zero from the start or set it equal to a small value.
+	So physically, one could say that both are equally correct (or equally incorrect).
+	As a numerical check, we have performed additional calculations with very small $\eta$ values and the corresponding quasiparticle energies are nearly identical.
+	Moreover, we do not have any numerical issues in our calculations.}	
 	\item 
 	{Figures 1, and the corresponding figures in the supplementary are plotted on a linear scale of X. 
 	Personally I think it is much more instructive to plot against X$^{-3}$, which will much clearer visualize convergence. }