http://cms.cern.ch/cds/EGM-13-001

Commenti di Marco C

The paper is too long and hard to read although its physical content is quite good

The language is often too much “cms slang” with expressions not of general understanding outside CMS

It has still the structure of an analysis note as it collects a list of useful and important informations but as a paper it should be more synthetic and coherent

giving to a reader the possibility to select the relevant numbers, that should be for example summarised at the end of each main section.

More emphasis should be put into linking the performance of the electron reconstruction and selection with the main CMS analysis papers where these numbers are used to build up the systematics

More work is needed to make it mature to be published

Commenti di Stefano A

The Torino group would like to acknowledge the authors for this extensive and detailed documentation of electron reconstruction in CMS. The task was not a trivial one, given the complexity and the multifaceted nature of the problem and the many slightly different ways in which various analyses exploited the available tools for reconstruction, identification and selections of electrons.

However, the reading of the CWR draft left us with a few serious concerns (Type B comments):

1. We are afraid the use of scientific English in this document does not quite meet the CMS standards required for a journal paper submission. Grammar is shaky, repetitions can be often avoided, symbols and quantities are not always properly defined and in several occasions the text is simply incomprehensible. We warmly suggest a careful reading of the excellent guidelines for preparing CMS publications available at https://twiki.cern.ch/twiki/bin/view/CMS/Internal/PubGuidelines .

2. Connected to the above, the manuscript is very technical, which perhaps facilitated excessive use of CMS jargon. CMS jargon should be completely removed before going to FR. With this respect, the document as it stands is a very good CMS Analysis Note, but unacceptable for a journal publication.

3. The document is very long. We feel there are several opportunities to make it more terse by avoiding repeated text and concepts. Also, the number of figures could be reduced either by merging several plots into one or by avoiding showing many flavours of the same plot (e.g. when showing efficiencies for several working points).

Below we provide some suggestions. We started by providing line-by-line comments, but realised it was an impossible task within the given time : after a couple sections we marked only the most important problems. We are sure the LE has a lot of useful comments and can help making this a top-quality paper.

A curiosity : the residual trend in pt in Fig 15 left is ascribed to the fitting function. We believe the fitting function should bias simulation and data in the same way, so we are left wondering if the explanation is sound.

Good luck for the implementation of comments and FR !

Type A comments :

Abstract:

“A few 100 GeV” - A few hundreds GeV

“cluster energy in the calorimeter” → the word “cluster“ is jargon and must be defined or avoided

“combining the measured energy in the calorimeter and the measured momentum in the tracker” → combining the energy measurement in the calorimeter with the momentum measurement in the tracker.

“The observed distributions of relevant observables are found to be well reproduced through Monte Carlo simulation” → The spectra of the observables relevant to electron reconstruction are well reproduced in Monte Carlo simulations, as well as selection and reconstruction efficiencies.

“The data to simulation efficiency ratios …” → We suggest to remove this convoluted sentence.

“The effective energy resolution .. changes “ → The energy resolution [you don’t explain what “effective” means just yet] for electrons produced in Z decays ranges from 1.7% to 4.5%, depending on pseudorapidity and energy losses via bremsstrahlung radiation.

Introduction:

L27: “such as those ..” → such as Higgs searches and properties, standard model precision measurements and searches for new physics.

L30 : “the basics .. established for” Rephrase, suggestion: The basic principles of offline electron reconstruction in CMS were outlined in the PTDR (ref), and rely on the combination of the energy measurement performed by the Electromagnetic Calorimeter (ECAL) and of the momentum measurement performed by the silicon tracker. This strategy delivers optimal performances over a wide range of transverse momentum (pt).

L32-33: consequently, remove this repetition (you already said the reconstruction combines E(ECAL)/p(TK))

L34: “In this paper .. means” → Throughout the paper, “energy” and “momentum” are used to refer to the energy of the electromagnetic shower initiated by the electron in ECAL and track momentum measurement in the tracker, respectively, while the term “electron energy” is used to refer to the combined information.

L36 There is no such thing as “the performance of the energy calibration” . Suggestion: ”The performance of ECAL in terms of calibration precision and resolution was reported in Ref , while track reconstruction is discussed in Ref 5

L38 “were some aspects .. also discussed” : drop

L40 “performance of the resolution” , again there is no such thing. Suggestion: “In this paper, electron reconstruction algorithms are described and their performance in terms of resolution, accuracy and identification capabilities is discussed, based on 19.7 fb-1 of data … ”

L44 “The needs for electron performance ..” Electron performance cannot “need” anything. Rephrase. Suggestion: “The cutting-edge physics analyses foreseen by the CMS scientific program demand high electron reconstruction and selection efficiency, small misidentification probability, and high accuracy and precision of the energy measurement over a large pt range.“

L46-7 “The most challenging physical process is the Higgs ..“ this is not at all true, as there is a plethora of low-energy decays which would be far more challenging. Suggestion “A crucial and challenging physical process to study, which is used as a benchmark in the present report, is the decay of the Higgs into four electrons or two muons and two electrons, where one of the electrons can have a pt as low as 5 GeV. At the other extreme, electrons with pt above …”

L52 “Fig 1 shows the overall “ → “Fig 1 shows the full-range spectrum of uncorrected dielectron invariant-mass derived from data collected using [remove “relatively”] high pt dielectric triggers.

L53 “No correction … to these data” drop, it can be replaced by using the adjective “uncorrected” in the sentence above. If you really want to be specific, add “uncorrected for efficiency” at the end of the previous sentence.

L54 : “The drop of the spectrum” , well, it’s arguably an increase rather than a drop, unless you look backwards ! Suggest : “The step around 40 GeV” , or “the feature around 40 GeV“

L58 : remove “in front of the calorimeter”

L59 : “the tracker material … lead to significant emission of bremsstrahlung “ → “ cause significant bremsstrahlung emission along..”

L64: Add the sentence: ” The paper is organised as follows” L69 : “are shown” → are presented

Caption to Fig 1 : → “The full-range spectrum of uncorrected dielectron invariant mass ..” Drop “ No correction ..”

Section 2 Line 80: the new CMS publication rules allow dropping the definition of pseudorapidity

L80-85: very convoluted. Just say how the coordinate system is defined, and then that its center can be placed either in the geometrical center of the detector or in a primary vertex (we believe this is what you mean ?). A direction cannot be measured relative to a point, this is plain wrong.

L83 : “unless specified to the contrary” → unless otherwise specified

L90-91 : “offering for eta<2.5 an active detection region (the acceptance) “ : sorry, what ?

L101:“ A consequence of the silicon tracker” → “A consequence of the presence of the silicon tracker”

L107-109: these concepts have already been discussed in L58.

In summary, we wonder if Section 2 could be made shorter, since it does not really say anything new.

Section 3

L143 “in a fixed time interval of less than 4 us” → in 3.6 us

L146-157: please rewrite this paragraph explaining properly what a trigger tower is, defining “cluster”, etc.

L 158-160 : the sentence says nothing, the reader does not know what a L1 or HLT electron candidate is.

L 165 “unbiased sample relative to the consider efficiency” not clear

L167 “cluster in the ECAL that forms an invariant mass with the first electron” a cluster does not form an invariant mass

L173 drop the word “dedicated”

L177 “their results compared to evaluate the systematic uncertainties” : please clarify. The results from MadGraph and Powheg are compared with each other ? Which systematics are evaluated ?

L184 after .. reweighting good agreement is found “ isn’t this obvious form the definition of reweighing ?

L195 “previous bunch crossings” : previous to what ?

Section 4

L 197 “a track in the tracker” → a track reconstructed in the silicon detector L 197 “ a cluster of energy” : we believe “cluster” was never properly defined L 199 “used to maximise both the performance and the similarities with the trigger stand-alone strategy” : this sentence is really obscure to the non-initiated

L207 “this spread can be quite restricted”: rephrase L215 “along the phi direction relative to the initial direction of the electron” what does it mean ? Radiation is emitted along the phi direction, period.

L217 “two super clustering algorithms” : supercluster is not defined

L220 -249 : these paragraphs are full of jargon (“dominoes”, “seed”), undefined symbols (N_steps, etc), unreported values (value of ET^min_seed e.g.)

L266 “makes this a non optimal” → a sub-optimal L267 “there is a too large of a change in curvature due” → when the change in curvature is large because of bremsstrahlung

L281 “general tracks” : please check if they were ever defined L290 “a subset of the seeds leads eventually to tracks “ ?? L339 “the track stops collecting hits” : it’s hard to believe that tracks can “collect hits” L357 “a dedicated Bethe-Heitler function” : what is a dedicated Bethe-Heitler

L399 “emit high fractions of their energies” → rephrase

L403 “difference in the material” → imperfect modelling of the material budget in simulation L404 “access” → assess L407 define ”service region”

L423 “ECAL-driven seeded” : convoluted expression. BTW , we think “seeding” was never explained L433 “it is therefore not very restrictive in the direction along which … “ : puzzling

L449 “transition region” → boundary between EB and EE

L463-464: try to explain better L483 : “felt needed for the alignment procedure” : it’s not a matter of feelings, please rephrase

L536 “ observables sensitive” → suited to identify

L556 “ the end of the encaps” → the highest eta endcap regions

L581 “laser monitoring system” → add Ref

L611 it’s not the number that is reconstructed, but the vertices, flip the terms (“number of reconstructed interaction vertices”) L622 “CB with different parameters .. below and above the peak position” : explain better, the peak position is a parameter itself

L654 “can cause the corrections” calls for the introduction of the corrections ..

L659-660 : “The SC energy is corrected by changing …” : put in this way it is quite puzzling

L675 “The resolution of a SC energy is also affected by the sources of discrepancy” ???

L681-682 “smeared energy simulation” , define (we believe this is not the right expression) L684 “inflated” → increased

L687 “after all the steps are taken” → after the refinements explained in the previous sections

L716 “must be corrected further on top of ..” please rephrase

L726 “the breadth of performance in data”

L744 “the resolutions are smeared in simulation” : resolutions are not smeared

L756-757 “used ..used” .

L759-763: unclear

L772 “through of a method”

L786 : “electrons produced within ..” → originating form the decay of the b and c quarks

L807 “reconstructed electrons that match generated electrons …” rephrase

L809 “enough purity” rephrase

L831 etc: explain why sigma_ietaieta is effective in discriminating signal from background electrons L834-835 “obtained by counting crystals” rephrase

L852 “shape information is expanded “ ?

L891: “significant energy flow near their trajectories” perhaps “significant activity” ?

L897 : Introduce the paragraph by saying “Two techniques are employed …”

L908-909 : “the calibration that corresponds … used to define their contribution” really obscure L915-918 : obscure as well

Formula: please ensure you write a sound mathematical formula

L928: “among the most sensitive observables” → among the observables more sensitive… L932 A_eff not defined

L989-990 : please check if d0 and dz are defined

L994 “90,80,70%” we lost track of what the three numbers may refer to L1015, L1023 add Reference

L1072 “dependence.. on the number of bins used “ ?

L1087 : “to select both the events and the probe “ ?

Fig25/25 perhaps can be merged ?

Section 7 “Summary and conclusions”

In this section it is particularly important to avoid CMS jargon

L1155/56 “with a single-cluster supercluster” , “multi-cluster supercluster” , perhaps we could refer to high-brem and low-brem electrons ?

References

References should be uniformly presented. E.g , Ref 25 has “Vol”, “No” while others have not (remove Vol, No, ). Some references have start and end page, others only start page (remove end pages from refs 25,31,36).