Difference: PaperReadingWjets (9 vs. 10)

Revision 102011-10-21 - SarahAllwood

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The paper draft is here:

The draft document may be found at this URL: http://cdsweb.cern.ch/record/1390459

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General Comments on the paper layout and Style

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Be consistent with the use of past vs present.

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Be consistent with the use of past vs present tense.

Comments on the analysis/methodology

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It won't significantly change the result, but why use powheg+pythia for ttbar together with MC@NLO for single top? It would make more sense to either use MC@NLO for both processes (since there is interference between the two) or else to use AcerMC for single-top, as it is considered to describe the %$ P_T$% spectrum for additional b-jets better than MC@NLO.

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It won't significantly change the result, but why use powheg+pythia for ttbar together with MC@NLO for single top? It would make more sense to either use MC@NLO for both processes (since there is interference between the two) or else to use AcerMC for single-top, as it is considered to describe the %$ P_T$% spectrum for additional b-jets better than MC@NLO.For the future this should be considered. This enhances the utility for this study as a background measurement for top and higgs.

Specific comments on the text

Abstract

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line 5: "up to 5 jets" seems to imply that the measurement is in bins of n excusive jets, however in fact the measurement if in bins of n inclusive jets. Obviously "up to 5 or more jets" doesn't work, but there must be a better way to write this.

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The comment is made that "mostly found to be in good agreement with data" but certainly pythia is bad for more than one jet, the rapidities indicate low x gluon is off, and for 20 gev jet cuts sherpa is way off. It would be great to give a consise set of these conclusions here.

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139 The use of online and on-line is not consistent. It is also imprecise
to say online - it should be defined in terms of the algorithms
and corrections in the introduction. Similarly for offline.
Saying selected "online" is just saying triggered?

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L150 – Suggest removing “as required in this analysis”

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195-200 use semicolons instead of commas to separate the list items.

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212 Is the min bias here matched to what was measured (by Glasgow?!)

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//212 Is the min bias here matched to what was measured (by Glasgow?!)

V Off-line Event Analysis

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L245-L247 – I think this sentence needs re-phrasing. Maybe something like: “Since a jet involves many clusters, the mass and rapidity, rather than pseudorapidity, can be determined.”

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254 pt>30 to be reliable but we use 20 in the paper too so perhaps
that is just absorbed in systematics so reliable is not a useful
characterization.

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//254 pt>30 to be reliable but we use 20 in the paper too so perhaps
that is just absorbed in systematics so reliable is not a useful
characterization.

line 271: use \mbox to prevent wrap around of the inequality for JVF

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reliability of simulation of an electron as a jet is very good. You just need to get the calorimeter total energy response right (more or less).

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For jets faking electrons the reliability is much worse because the simualtion has to get fine details of the ahdronic shower correct (e.g. every variable that we cut on in the electron finder)

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For jets faking electrons the reliability is much worse because the simualtion has to get fine details of the ahdronic shower correct (e.g. every variable that we cut on in the electron finder)

is it unreliable or amount of MC not feasible.

372-381 Confusing as to what is actually changed. Perhaps the cuts should
just be given in a table.
Fig 4: This one has a supressed zero but Fig 2 does not.
The qcd distributions are not smooth and should either be
smoothed (interpolate with sys on interpolation) or discarded
with some upper limit for sys.

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L426, L429 – I don't think you need to put this statement twice, you've already referred to Table III in lines L405-L406.

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Yield tables are not included anywhere -they should be.

D. Wmunu

Fig 5: Also ratty qcd: >=5j with 80 GeV mt is artificial. >=3 is quite
ratty.

441 Does the cut at 10mm cut out a lot of lumi ?Does this compare to the
beam spot cut of 60mm?

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sigma of beam spot size in z?

What is Z wrt? is it primary vertex?

L479 – for consistency, multi-jet --> multijet.

L481-L483 – Suggest re-phrasing.

490 The background events with a muon and an energetic jet dont survive?
To what degree and what happens when we have 2fb?

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Please clarify, we don't understnad these lines. 486-490

L499 – multi-jet --> multijet.

L526 – Again, don't think this line is needed since you've introduced Table IV in L507-508.

E. Detector level comparisons

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544 The discrepancies are within systematic are they?

549 The sentence should perhaps be "The predicted ttbar cross section
of 165+11-16 is used instead of the less well determined but
consistent value of 171+-...

Fig 7: The last point in the first jet pt for miuons is ok for electrons
but disagrees in muons because of a spuriously weighted event in the
highest bin!

Up to this point the cuts for MET were released. What cuts are used
for this figure compare to the ones used in making the templates?

The pt is not uncorrected -- it is corrected for detector effects
but not to parton level. This is a confusion throughout the paper
and one cannot be sure when looking at a plot what the real pt
definition is. In fact the utility for background computations is
limited by the fact that any physics measurement in top or Higgs
will use a reconstructed parton correction. Here the step is
to do a comparison with MC but distributions for the corrected
parton are useful. It is also confusing what JES correction is applied.

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//544 The discrepancies are within systematic are they?

//1 QCD event pushes up the estimate? - no it's a log plot.

549 The sentence should perhaps be "The predicted ttbar cross section
of 165+11-16 is used instead of the less well determined but
consistent value of 171+-...

which one did you use.

//Fig 7: The last point in the first jet pt for miuons is ok for electrons
but disagrees in muons because of a spuriously weighted event in the
highest bin!

//Up to this point the cuts for MET were released. What cuts are used
for this figure compare to the ones used in making the templates?

//The pt is not uncorrected -- it is corrected for detector effects
but not to parton level. This is a confusion throughout the paper
and one cannot be sure when looking at a plot what the real pt
definition is. In fact the utility for background computations is
limited by the fact that any physics measurement in top or Higgs
will use a reconstructed parton correction. Here the step is
to do a comparison with MC but distributions for the corrected
parton are useful. It is also confusing what JES correction is applied.

Fig 15 caption “left: electron channel, right: muon channel” should be “top: electron channel and bottom: muon channel”

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611 Why would electrons need such a huge correction?

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detector to particle level correction is confusiong . It's an efficiecny.

F. Overall Systematics

665: space needed after pT

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675: I'm sure I've missed something here, but why 11% for 1jet bin here and 9% in table V. And for 4jet bin it's 56% in the text and 35% in the table.

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675: I'm sure I've missed something here, but why 11% for 1jet bin here and 9% in table V. And for 4jet bin it's 56% in the text and 35% in the table.What is the difference.

Fig 17: is this a linear or quadratic sum of the other systematics? It should
say "linear" sum or "quadratic" sum

Fig 18: The "no pythia" should be on this one and appears on others.
Also the tick marks don't appear all thetime on all points.
This is true of many figures.

Fig 19: Was the ratio figure left out?

Fig 20: Odd statistical issue in Blackhat-Sherpa for the first bin. Either
need to rerun or remove the point but of course it is odd not to
have all points matching data...

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869 Would be good to reflect these conclusions in the abstract.

Fig 26: In spite of what the abstract says, sherpa is very poor here

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Figure 19 – In the caption you mention “and the ratio of theoretical predictions to data” but there is no such thing in the figure, or is it?

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//Figure 19 – In the caption you mention “and the ratio of theoretical predictions to data” but there is no such thing in the figure, or is it?

Appendix A

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Should show us the QCD templates again as well. They had
some odd features statistically that misled us to interpret
some of the extremes of distributions.

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Should show us the QCD templates again as well.

///They had
some odd features statistically that misled us to interpret
some of the extremes of distributions.

line 1119: "cross sections to be more" -> "cross sections more"

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