Dear Monica, dear Giulia, Below are the comments on behalf of the Nikhef group. We found the paper very well written, and we only have a few textual suggestions. (We also hope to have caught a few typical EB comments...) Kind regards, Niels Main comments: ---------------- 1) L.47-49 This formulation is not completely logical? A direct connection is suggested between the amount of pile-up and the number of filled bunches, which are only indirectly related. How about simply: "During this period the average number of interactions per crossing varied." 2) L.82-87 Perhaps it is better to refer to the vector meson as 'V', rather than 'P', since many people use 'P' for pseudo-scalar. 3) L.190 You use an uncertainty of 8.6% from BR(b->J/psiX)=(1.16 +- 0.10)%, based on LEP data, if we understand correctly? It is a large contribution, and it is not so easy to trace this number in the PDG. It would be good to quote the PDG, and probably also the Delphi paper Phys.Lett. B341 (1994) 109-122 , which is the most precise, to indicate this comes from Z-decays. 4) L.220/221 Why did you choose not to assign a systematic uncertainty to the extrapolation to 4pi ? 5) L.235-237 You use the notation B^iS. The explicit notation BR(Y(1S)), BR(Y(2S)) and BR(Y(3S)) is more clear, still dense enough for the figure axes. The notation R^iS/1S refers to only two variants, R^2S/1S and R^3S/1S and could also be used instead of the 'iS', and R^(2S,3S)/1S on the axis labels. 6) L.236 Add '(corr)' and '(uncorr)' behind the errors in the result, to make it clear it is not (stat) and (syst) as usual. L.239 In fact, what do you mean with 'correlated between bins' ? As this result is the integrated result, there are no correlations between bins? Presumably this comes form adding the binned result in quadrature? Perhaps this can be clarified with a sentence? 7) The supplementary Fig.13 could also fit nicely in the body of the paper? Minor textual suggestions: --------------------------- General: * Usually the use of subsections is discouraged. Either promote to separate sections, or demote and omit the subsection? * decaytime -> decay time * in the Figure captions, (a), (left), etc, should come before the description, instead of after. Title page ---------- Title: [How about adding cross section to the title?: ] "Production cross-section of J/psi and Y mesons at sqrt(s)=8 TeV" [please add the copyright statement;] {\footnotesize {\footnotesize \centerline{\copyright~CERN on behalf of the \lhcb collaboration, license \href{http://creativecommons.org/licenses/by/3.0/}{CC-BY-3.0}.}} \vspace*{2mm} Abstract * [add comma's] ', and the fraction of J/psi mesosn from b-hadron decays, ' 1 Intro ------- L.9 into a heavy -> into heavy L.14 data as -> data, as L.16 [9] reducing -> [9], reducing L.22 Double Parton -> double parton L.23 [better to avoid possible confusion with beam energy: ] at 8 TeV -> at $\sqrt{s} = 8$~TeV 2 LHCb ------ L.46 of the 8 TeV run in April 2012 -> of the data taking period at sqrt(s)=8 TeV in April 2012 L.48/49 "... is based on a data sample that corresponds to an integrated luminosity of about 51 pb-1 ..." L.50/51 ['mesons' plural, small rewrite of int.lumi, and replace 'one' by '1.0' to match the '1.3' mentioned on L.50: ] " ... more abundant J/psi mesons is based on data corresponding to an integrated luminosity of about 18 pb-1, collected with 1.0 visible .. " 3 Selection ------------ L.70 [comma] region, defined L.72 made on -> applied to L.73/74 [shuffle: ] 'the decay time is required to be less than 0.3 ps, as estimated from the propagation of the uncertainties given by the track fit.' L.75 'otherwise give problems in' -> 'otherwise complicate' L.78 generate hadron decays -> simulate hadron decays L.83 [put 'in a bin ()' earlier:] '... of a vector meson V in a bin (pt,y), where V stands for ..., decaying into a muon pair ' L.87/88 'are the rapidity and pt bin sizes, respectively.' -> 'are the bin sizes.' L.91 precisely -> precise L.92 times -> and L.97 van der Meer -> Van der Meer 3.1 extraction -> determination L.101 [add comma] studies, prompt L.102 [add comma] decays, by L.106 extracted -> determined L.112 exponential decay function -> exponential function L.118 [a particle comes with a noun, but 'mass' is enough: ] J/psi meson mass sidebands -> J/psi mass sidebands L.119 ', the negative ' -> ', where the negative' 3.2 extraction -> determination L.137 The masses ofthe -> The mean value of the mass of the L.138 Y(3S) are left free -> Y(3S) resonances are allowed to vary L.142 dataset -> datasets L.143 [add comma] range, while Fig.2 [add (pt,y) bin size in the figure, to make Fig. self-explained when showed. (Like you do in Fig.1b.) ] 4 Syst ------ L.154 'beacuse of the radiative tail' -> 'because of energy loss due to bremstrahlung' L.164 muon tracks reconstruction -> muon track reconstruction L.164 has also been L.165 [add comma] approach, based L.166 and found to be -> and was found to be L.169 [avoid twice 'that':] that exploits a sample -> exploiting a sample L.176 [add comma] 5%, dominated L.177 van der Meer -> Van der Meer L.186 background and perform an -> background, performing an 5 Results ---------- L.195 'and are compare with ' -> 'and compared to' L.195 predictions in the LHCb acceptance as well -> predictions, as well L.198 on the prompt -> on the measurement of the prompt L.202 and by up to -> and up to L.203 [add comma] bins under -> bins, under Fig.3 [add 'prompt J/psi' and 'J/psi from b' inside the figure.] L.220 [this importtant result justifies to become a separate equation.] L.230 [add comma] mesons, as seen L.231 [could you start the Y discussion after Fig.5 to keep the figures close to the text?] Tab.3 [move to top of page to stay close to J/psi text.] Tab.3 [1st row:] "2 - 2" -> "2.0 - 2.5" L.250 [to avoid confusion with beam energy: ] at 7 TeV -> at sqrt(s) = 7 TeV L.251 [could you start the section only after Fig.8, to keep the figures close to the text?] L.275 [repeat the result for convenience? It also emphasizes how precise the data is.] presented here. -> "presented here, 1.28 +- 0.01 +- 0.11." L.278 as a function of sqrt(s) -> 'as a function of center-of-mass' L.291/292 [sentence get a bit lost on the page. Maybe with new layout will be ok.] Fig.9,10,11 [in plot and caption]: 2 2.0