Comments on TOP-18-003, Andreas Meyer


=== All type B ===


* title: How about: "Search for standard model production 
  of four-top-quark events in pp collisions at sqrt(s)=13 TeV" 

* abstract: 
  - rather long, suggest to try to shorten.
  - suggest to drop mention of cut-based result.

  - 6 lines from bottom, suggest to split sentence: "... is the SM value of y_t. The Higgs Oblique Parameter (capitals?) is contrained ..."

* introduction

  - line 26: suggest to mention why the single lepton channel does not add anything. Quantitative statement ?

  - line 35: "detector developments" sounds a bit like detector R&D, suggest "change of detector configurations ..."

  - in the introduction also mention about how the different years are 
    treated, i.e. separate analysis and combination or analysis in one go ? 
    We understand it is the former.

  - line 39: remove mention of previous cross section prediction (at least from introduction)

* section 2:
  
  - around line 54: mention here or in introduction how different treatment 
    of uncertainties in different years can be combined (see above)

  - lines 68-71: it seems the _justification_ for the use of a narrow-width 
    approximation goes the other way round:
    The use of a simulation in the narrow-width approximation is justified because the searches performed here
    assume a narrow signal, and details of the mass reconstruction are not exploited.

  - lines 85 to 100 are a bit confusing. Better just mention that MC distributions are corrected to describe
    the data and details are given in section 6, and then give the full set of details at once.
    In the current version the passages in sections 2 and 6 are somewhat duplicate.

* section 4:
  
  - would we not gain from use of the single-lepton trigger ?

  - line 156-9: unclear what the isolation criteria really are.

  - BDT: 
    - why is the subdivision into 7 SR really relevant ? 
      Is this not a standard floating point output number ?

    - How were the input distributions to BDT determined ?
      To what extent are expected features like peaks in W-mass and t-mass taken into account ?

* section 5:
  
  - line 248: as a function of pt ?

  - line 254: ... is negligible ... -> ... is very close to 1.

* section 6:

  - line 272: why are the lepton ID uncs. so large ?

  - line 277: what is the significance of these numbers 1-15% and 1-10% ?

  - line 279 and following: (see comment above) suggest to information in and reference to section 2, and 
    put the full information about the reweighting procedure here

  - line 317: this is a bit confusing: experimental uncertainties are 
    fully correlated across bins, but not across years ? Specify more clearly which correlation is
    referred to and motivation.

  - at some point in this section introduce nuisance parameters such that table 2 can be understood.

* section 7:

  - figures 1, 2, 3:
    - tttt contribution is invisible in b/w 
    - axis titles (and labels) are very small (also for other figures)
    - propose to spell out figure titles "SR, CRW, CRZ, Cut-based ..."