<div dir="ltr"><div class="gmail_extra">Dear Volker,
</div><div class="gmail_extra"><br></div><div class="gmail_extra">thanks a lot for your feedback.</div><div class="gmail_extra"><br></div><div class="gmail_extra">While working on your suggestions, let me forward you the exchange we already had with Sebastian Khun about the C12 BSA plots, and the conclusions we drew from it.</div><div class="gmail_extra"><br></div><div class="gmail_extra">Best regards,</div><div class="gmail_extra"><br></div><div class="gmail_extra">silvia</div><div class="gmail_extra"><br></div><div class="gmail_extra"><br></div><div class="gmail_extra"><div style="font-size:13px">----------------</div><div style="font-size:13px">Sebastian's comment:</div><div style="font-size:13px"><br></div><div style="font-size:13px">"Overall a nice paper with very interesting results. I have only one "serious" concern: You are showing the A_LU results for both 12C and 14NH3 in Fig. 17 and then comment that they are "compatible". However, the deviation is at 3 sigma, which is certainly not insignificant! Furthermore, it looks like nearly ALL the 12C data are shifted UP from the 14NH3 ones, to the extent that I am wondering whether they are even consistent with an average of zero (as physics says they must be). It is one thing to say that we do not have precise enough data to be sensitive to medium effects (which is undoubtedly true). But I would like to see a bit more discussion about the 12C "anomaly" and, in the discussion of systematic uncertainties (V.12), an accounting of the uncertainty coming from the fact that we really don't know A_LU for the 10% "nuclear background" (at least not very well) from the data alone."<br></div><div style="font-size:13px"><br></div><div style="font-size:13px">----------------</div><div style="font-size:13px"><br></div><div style="font-size:13px">Our answer:</div><div style="font-size:13px"><br></div><div style="font-size:13px">Your point about the c12 has been raised during our Ad Hoc review. We checked already at that time the form of the distributions, fitting it with the addition of a constant term. The results are in </div><div style="font-size:13px"><br></div><div style="font-size:13px"><a href="http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/?play=http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/test_bsa_c12_nh3_noden.png" target="_blank">http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/?play=http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/test_bsa_c12_nh3_noden.png</a><br></div><div style="font-size:13px"><br></div><div style="font-size:13px">First plot shows the comparison among the two asymmetries, and, even though the c12 - red points - are usually bigger than the nh3 ones - blue points, they are compatible for almost all of the bins. The middle and right plots show the fit to the c12 (middle), nh3 (right) bsa with the standard bsa function, where p0 is the constant term and p1 the sinphi modulation. As you can see, p0 for c12 is compatible with 0 in 1.5 sigma. The other modulations are perfectly compatible.</div><div style="font-size:13px"><br></div><div style="font-size:13px">Bear in mind also the fact that these are raw asymmetries, not pi0 subtracted, and such a subctraction cannot be performed on c12 due to the even more limited statistics on pi0 events.</div><div style="font-size:13px"><br></div><div style="font-size:13px">Given this statistical limitation, it is hard to draw any conclusion, or also think of implementing any kind of systematics from this. The BSA on c12 that you see is integrated over the whole part B, and trying to estimate a systematics from it would be a sort of Ansatz, not including possible dependences etc. Furthermore, it would be estimated on a different observable, i.e. the raw asymmetry, instead than on the real, subtracted one.</div><div style="font-size:13px"><br></div><div style="font-size:13px">Your comment, in any case, pushed us to go back and investigate more throughly the C12 analysis. We found out that due to the limited C12 statistics the BSA is very sensitive to the statistical fluctuation coming from the variation of the exclusivity cuts. In order to be sure that there is no sistematic effects but only a statistical one, we compare the BSA on c12 and on nh3 in the two extreme cases of the exclusivity cuts, i.e. the one corresponding to the 2.5 sigma and the one relative to the 3.5 sigma from the central value of the cut estimated following the procedure described in the analysis note.<br></div><div style="font-size:13px"><br></div><div style="font-size:13px">At the following links you can see the results relative to these two scenarios:</div><div style="font-size:13px"><br></div><div style="font-size:13px">2.5 sigma case: <a href="http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/?play=http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/test_bsa_c12_nh3_2.5sigma.png" target="_blank">http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/?play=http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/test_bsa_c12_nh3_2.5sigma.png</a></div><div style="font-size:13px"><br></div><div style="font-size:13px">3.5 sigma case: <a href="http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/?play=http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/test_bsa_c12_nh3_3.5sigma.png" target="_blank">http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/?play=http://www.lnf.infn.it/~pisanos/dvcs/prd/c12/test_bsa_c12_nh3_3.5sigma.png</a></div><div style="font-size:13px"><br></div><div style="font-size:13px">together with the results on the fit of the bsa on c12. As you can see, the asymmetry are perfectly compatible, and no shift is observed in the c12 (p0 in the fit box).</div><div style="font-size:13px"><br></div><div style="font-size:13px">Since these are the two extreme cases and not effects are seen, and being the final contamination - dilution factor - around 8%, we concluded that not further systematics was needed.<br></div><div style="font-size:13px"><br></div><div style="font-size:13px"><div>This said, however, in the systematics studies we did, the one relative to the variation of the exclusivity cuts takes somehow into account possible effects from nuclear background, since, as you can see from Fig. 15, varying the cuts it varies the c12 contamination, and should then include any sensitivity in the BSA emerging from an increased nuclear backgroud.</div><div><br></div></div><div style="font-size:13px">We realize now that that kind of plots in the final paper could be misleading, and therefore we have decided to remove it and to add a little more explanation in the text. Here is a summary of our reasons to remove the figure:</div><div style="font-size:13px"><br></div><div style="font-size:13px">1) That figure is supposed to justify why we present the BSA with this data, despite the fact that there is some background from the N14 and therefore it is not the standard free proton BSA. We think that this is not a concern since our background is just 8% and we are applying tight exclusivity cuts which ultimately select N14 protons at quasi-free kinematics;</div><div style="font-size:13px"><br></div><div style="font-size:13px">2) It would be a concern to have such a background if our results were disagreeing with the BSA measured on free protons (FX et al) but Figure 19 shows that we are consistent;</div><div style="font-size:13px"><br></div><div style="font-size:13px">3) C12 and in particular C12 BSA is not used anywhere in extracting the results. We only used the total counts of C12 to get the dilution factor.</div><div style="font-size:13px"><br></div></div></div>