http://cms.cern.ch/cds/BPH-13-012
Roberto
Dear xxx,
(la mia opinione qui è: il contenuto è ok, molto stringato ma immagino sia perchè vogliono mandarlo come letter, invece l'inglese non è eccezionale, ma vedi anche gli altri)
General: - Quantities related to the paper are named in several different ways throughout the paper: phi_s for example is “CP violating decay phase” in the abstract, then “Bs meson decay phase” in L4 (I do not think decay phase is correct in English), then “weak phase” again, etc. It would be better to stick to one definition and then just say phi_s. Same is true for ct, for example, which is explained with a very long definition more than once.
- There are places where the reader has no feeling if a specific choice has an impact on the result or not, and if yes, which checks/systematic uncertainties, e.g.: L122: “samples used to determine efficiency corrections are simulated with the DeltaGamma_s parameter set to zero” L235: “delta_0 is set to 0 and the difference of phases […] to reduce correlation between parameters” It would be good to comment if these choices change the result in any way and how it was checked, otherwise just leave them out from the text.
- Possible fit biases are studied using toy MC (L298). However, it would be good to state first if the fit on the FullSim signal produces any bias on the fitted variables.
- Did you do any check that, if efficiency is estimated with a sample having the physics parameters found in data, the result does not change (with reweighting, for example)?
Specific: Abstract: l5: “the values OF phi_s” l6: Is “flavour-tagged analysis” correct English?
- l16: f0 → f0(980) - l22: “possible contributions to the result from the non-resonant J/psiKK are considered”: where is this discussed in the following? - unnumbered lines before 32: define Deltam_s - l36: “phases” → “STRONG phases” - l37-38: very awkward sentence and B_L is not defined.
- l76: is the primary vertex already reconstructed at the HLT or do you use the online beamspot? If PV, please add reference on the procedure to determine it. - l87-89 are a repetition of l80-81, so probably they should be moved upwards. - l96: “fitted with a combined vertex and kinematic fit” must be improved - Figures, all to be fixed (remove preliminary, luminosity outside plot etc.) - l101-102, again do they also apply to HLT selection? - “EvtPVVCPLH module” of course must be explained or referenced… - l116: How is ct computed? From d_xyz/p? From d_xy/pT? A formula should be given. - l126: “cross terms”: Do you mean “correlations”? - l130: “and a sigmoid function”: “and” means a sum of the two or an alternative? “Variations of the lifetime efficiency”: Variations vs. what?
- l142: “b mesons” → “B mesons” - l159-160: why is the “d_xyz of the muon required to be smaller than 1mm”? The second B could also have a long lifetime, no? - l160: why “MINIMUM” angular distance? Is it just angular distance? - l167: “the leptons contributing to the wrong…” → “leptons providing the right tag information from those resulting in a wrong tag decision” - l170-171: “parameters” → these are actually variables, not parameters - l177: “the mistag probabilities are obtained”: what about tag efficiencies? they seem also taken from the same sample. - l178: in this case “B+ → J/psi K+”, where you also mean charge conjugate, is misleading because you immediately mention the charge of the kaon - l218: “m” becomes “mBs” in the following - l220: is omega determined from the value of MLPNN also a variable of the event? Why is it not listed? - l221: 49000 signal candidates is an estimate from a fit? Please explain. - l222: “mass range” is actually also a ct range - Likelihood formula: No mention of an extended likelihood term is done (which I think is there, otherwise it is not possible to determine NBG and NS as absolute numbers) - l230: “event likelihood function” → “value of the likelihood function for an event” - l239-241: There is certainly a better way to write this sentence - l255: if csi is only +/-1 is it correct to talk about a Probability Density?
Figure 5: - There seems to be a data-fit mismatch around |cosThetaT| = 1. Is it understood/mentioned? - l283: ct in Roman (3 times) - Caption table 3: “square root of… etc.” → “quadrature sum” - 323 “muon and the electron” → “muon and electron”
Linda
- Fig 1: non la trovo molto chiara, perché mi pare di aver capito che si riferisca a due sistemi di riferimento diversi (quello a riposo della J/Psi e quello a riposo della Phi) e credo che forse sarebbero più comprensibili due figure distinte (perché altrimenti si hanno 2 K+K- che sembrano 4 particelle diverse e invece, credo, siano sempre la stessa coppia).
- A parte nell'abstract, fino ad articolo inoltrato non viene ripetuto che la J/Psi decade in mu+mu- e forse sarebbe meglio ribadirlo nell'introduzione, almeno prima della figura.
- line 80: The trhee-dimensional distance of closest approach of the two muons: aggiungerei “from the primary vertex”
- line 283: “ct” in corsivo.
Stefano
We'd like to congratulate the authors for completing this important and difficult measurement. The paper is well written and we don't have major complaints. The clarity of some paragraph can be improved, and we suggest the language editor gives a second pass to the text. Also, a second look at the CMS guidelines for publication will be beneficial. Details below. Good luck with FR and Journal Refs !
Type B Comments
Clarity: the flavour tagging section is particularly hard to understand. In detail:
- Mistag probability sample L177 on. Not clear how the decay B+→Jpsi K+ is used to measure mistag probability. Is the idea to look for the semileptonic decay of the B- on the other side of B+→Jpsi K+ ? If so, it should be said explicitly. Do you really use only B+ or do you mean B+/B- ?
- Choice of parameterization of \omega: “limit the correlation ..” L201 Please explain.
Efficiencies. It seems they are completely derived from MC. Was is possible to perform any data-driven cross check ? It would be nice to add more details about how the efficiency corrections are derived (\epsilon(\Theta))). What are the “three dimensional angular efficiency histograms ” L125 ?
kappa factor, L238. Not clear what it is. “In order to resemble the actual resolution” ?? the sentence has no subject. Please rewrite L238-L240. I am particularly confused by the statement that kappa is measured in simulation by assuming that it is the same in data and MC. One would naively think it is introduced to match the resolution observed in data and MC.
Fit bias: “used as a systematic uncertainty if the difference with respect to the model bias exceeds (the) one standard deviation” L305. Standard deviation of what, of the pull distribution ? You should use the error on the mean of the gaussian fit to the pulls. The sigma of the pull distribution should always be close to one. Please explain. In any case, was this procedure checked with the Statistical Committee ? I think you would be better off by always including the bias in the uncertainty. You do include it for phi_s and DeltaGamma_s anyway, who cares if for the other parameters we enlarge systematics a bit.
Results: Please compare with other experiments. There is no flavour of how CMS performs wrt to other measurements of the same quantity. Consider for example adding CDF, LHCb and Atlas to the plot of Figure 6. Otherwise a sentence will be fine.
Table style: CMS rules are to use \topcaption, to put captions on top of the tables
Figures: - Figure 2: the units on the y axis are funny. Please redo the plot in units of Events/ 3 MeV to avoid using 6 digits.
- Figure 3 left: use Events / 35 um on the y axis label, or at least 0.035 mm - Figure 3 right: again Events / 9.4E-05 cm does not seem a suitable binning. Consider removing this plot altogether.
Acknowledgments: please check if you should rather use the long version.
Type A
L 3: consistency of the SM → its consistency L 6: stems → originates Section 2: No need to split paragraphs IMHO. L136 “muon or electron” add “in the following “tag muon or electron” ” L179, L191 : parametrization→ parameterization L274: covariances→ correlations L278: “make the simulated ..” rephrase “by reweighing simulated events in order to reproduce the kaon pt spectrum observed in data ” L287: “the difference of the resolutions” rephrase: “The k factor is varied within the values observed in data and MC” L291 “arising form this source” → “the associated systematic uncertainty”
End Stefano