paper draft HIN-18-018
CWR comments by Joscha Knolle
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title: "study" -> "measurement"
Abstract.8: "is proposed to estimate" -> "is used to measure"

general: The title talks about "quark-like" and "gluon-like" jet fractions,
while the introduction (ll. 13, 15, 29, 42) and most of the paper talk about
"quark" and "gluon" jet fractions. Either, change the title, or introduce the
terms "quark-like" and "gluon-like" somewhere in the introduction and motivate
why this nomenclature is important.

l. 35: The definition of "background" here is not very clear. It might help to 
state explicitly that "signal" are single jets within events (and not full
events), and "background" refers to other partons in the same events whose 
shower is partly reconstructed as part of the signal jet (did I understand that
right?)

l. 54: Motivate the choice "abs(eta)<1.6". None of the following detector
coverage details explains this choice. Also, in l. 119 a cut of "abs(eta)<1.5"
is applied, also without motivation. Why these many different numbers? Please
explain in the paper!

l. 96: I don't understand this reasoning.

l. 120: I guess you mean "25% of pp events with one selected jet also contain
another selected jet", not "25% of all pp events contain two jets". Please
reformulate in an unambigious way. Also, what about PbPb?

l. 156: Be more specific on what is the "final-state particle level", e.g. is it
before or after hadronization?

l. 224: Why is there a difference for positive and negative particles?

Fig. 3/4: Show the total uncertainties (stat+syst) as well!

Fig. 6: How is "gluon-like jet fraction" defined? Especially, does it mean gluon
vs gluon+up+down, or gluon vs gluon+up+down+other?