Dear Ivan, Victor and Vanya,

We have read your paper with great interest.
Please find below the comments on behalf of the Nikhef/VU group.

Best regards, Niels

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Main comments/questions
========================
L.14 [Does the range of predictions 0.47-0.49 refer to the central values?
Do you have an estimate of the uncertainty on these numbers?]
L.102 [Please give the Bc yield here (which are only quoted on L.191).]
L.118-122 [this paragraph fits better between L.102-103, when Fig.1 is described.]
L.142 [Wrong charges on kaons, and no charge conservation: Bc+ -> J/psi K-K-pi+]

Tab.2 [The +-5% unc due to fit model seems very large? Tab.6 in the ANA note 
suggests that exp or CB all increase the yield, but not more than 4%?
Did you consider an asymmetric uncertainty?]

L.198 [The quark content of \bar{K}*0 is (s dbar), right? Then the
decay of the Bc+ should go to J/psiK*0K+ final state, without bar? ]
L.198 [Did you consider to quote a result for Bc->J/psiK*0K+?]
L.198 [For our curioisity, does the fraction of resonant decays to 
J/psiK*K+ agree with expectations from tau decays?]


Textual suggestions
===================

Abstract
--------
L.4 [skip, not really needed:] 
"taking into account the systematic uncertainties" 
L.7 second one is -> second is

1 Intro
-------
L.4 [suggest a rewrite:]
"with either the c or b quark that decays, or through annihilation 
of the quark pair [1-6]."

2 Detector
----------
L.46 [It sounds as if both models are implemented simultaneously. 
How about this?]
"The program has different Bc->Jpsi form factors implemented,
calculated using QCD sum rules [15] or using a relativistic quark model [16]."

L.49 extracted from tau decays -> taken from tau decays

3 Selection
------------
L.62+63 'chi2 of impact parameter' -> 'impact parameter chi2'
L.72 K-K+pi+ system -> K-K+pi+ combinations
L.77 of Bc candidate -> of the Bc candidate
L.78 of Bc candidate -> of the Bc candidate
L.86 width of vetoed -> width of the vetoed
L.88 [suggest to skip 'Finally' and don't start new paragraph.]
L.88 [skip, because it is obvious:] "calculated with respect to the PV"
L.89 [suggest rewrite: ] "The upper edge, in excess of 7 lifetimes " ->
"The maximum decaytime, corresponding to 7 lifetimes " 

4 Yields
--------
L.97 yield, determined -> yield is determined
L.99 respectively, is found -> respectively, and is found
L.103-105 [suggest a rewrite:]
"The resonant structures in ...., and JpisK+ combinations are studied,
and the possible contributions from ...., 
followed by the subsequent decays .. and .. are investigated.
The sPlot technique..."
L.113 width fixed -> width are fixed
L.114 statistical. -> statistical only.
L.117 vixible -> visible


5 Efficiency
------------
L.124-125 [suggest rewrite:]
"In the measurement of the ratio of branching fractions many potential
sources of systematic uncertainties cancel ..." 

L.129 Systematic -> Sources of systematic
L.130 [skip:] 'due to effects'

Fig.2 [caption: suggest rewrite:]
"The (blue) full line in the Kpi mass distribution (a) is composed
of the resonant K* contribution and the non-resonant contribution
indicated by the dashed line. 
The (blue) full line in the other mass distributions (b-f) show the 
predictions of the model used in the simulation.
The regions ... from the analysis, and are indicated by the shaded
regions on Figs. (c) and (d), respectively."

L.137 [shorten:] 'determine the uncertainty and amounts to 5%.'
L.148 is equal to 4.2%. -> is 4.2%.
L.153 the analysis selection criteria -> the selection criteria
L.154 [suggest rewrite:]
'the criteria are varied to values that correspond to a 20% change'
L.157 form -> from
L.157 uncertainty of -> uncertainty on
L.161 to that of the mass observed -> to that observed
L.162 is observed -> is seen
L.168 [skip:] 'According to this study'
L.169 is sensitive to -> depends on

Refs
----
[8] [twice:] Collaboration -> collaboration 
[30] [there is a recommendation - also in template now - 
to update this reference to include:]
 "and 2013 partial update for the 2014 edition"

[36],[37] [Perhaps we should consider updating the tracking reference
to the recent CERN-LHCb-DP-2013-002, which is in 1st circulation now?]