• P15 dRbb reweighting: 
    • Assumption: independent of V+jets flavour
    • Independent for each channel and pTV bin: how different is the correction in each channel and pTV bin? Motivation: 
      • didn’t get good closure when inclusive; different phase spaces
      • More freedom in the fit to pull the associated systematic uncertainties, which are also per channel/pTV bin
      • Less constraints; not propagated to different channels/bins
    • Impact of uncertainties on signal extraction is small
      • Because of mjj window cut in SRs
      • Main effect is on V+HF CR; lower mjj cut? Yes, p17 simplified description: V+HF CR: 50 GeV < mjj < 250 GeV
    • One shape unc. per pTV/bin channel included in the final fit
    • Different samples for 2016 and 2017+2018; mismodelling in both? No, correction only for 2017+2018; well-known issue of MADGRAPH5aMC@NLO v2.3.3 using the FxFx merging scheme. For 2016 using LO sample.
      • What is the cause of the issue in MADGRAPH5aMC@NLO v2.3.3? Not sure; possibly merging of soft jets
  • How much V+LF background is still left in the SR? Dedicated V+LF CR; means quite substantial? No. Also, because b-tag score is used in the DNN → V+LF usually to the left of the distribution in the SR 
    • Fitted distribution in V+LF CR: pTV (see p22)
    • …
  • P25-31 20 normalisation factors (NFs): why split in lepton flavours? Should expect the same modelling for ele and mu channels… 
    • Main reason: improves goodness of fit; account for different phase spaces
    • Postfit values are the same within unc as expected
    • Constrain Wenu+HF and Wmunu+HF NFs from 1L; how propagate to 0L? 
      • Taking the average in 0L; done by fitting simultaneously 2NFs in the 3 regions of 0 and 1L
      • Extrapolation unc. from 1L to 0L (i.e. nuisance parameter with a prior in 0L)? No; but experimental unc lepton eff / MET trigger provide degree of freedom that could be used by the fit but are not, i.e. there are no related pulls in the fit
  • p23 Plots show only 59.8 fb-1, from fit to full Run-2 dataset? Yes, fit is done in all the regions (~80) shown in p18/19 times 3 years; i.e. each region is separately for 2016, 2017, and 2018 and the fit is performed simultaneously to all the regions.
    • Plots are just examples; considering making all the regions and years public
    • So you also have year-dependent NFs? Yes. Are they consistent across the different years? Yes.
    • Motivation for splitting by year? 
      • Different detector performance 
        • Object calibrations provided individually per year? Yes.
      • Some simulated samples are different for the years (e.g. V+jets)
  • P23 HF DNN
    • One output node per process? Yes
    • But then fit all together? Yes
    • In addition to ttbar dominated bin in HF DNN still have dedicated ttbar CR? Yes
      • How much is the gain of having both? Not much. 
      • This is 0L; in 1L even more dominated by ttbar, but wanted to be harmonized between channels 
  • Why have separate regions for ele/mu channels in 1/2L? Improvement in goodness of fit. Also, different triggers, reco etc so having them separately seems more correct. But indeed don’t expect nor see any differences. 
  • P24 How are the “large prior uncertainties” for the category migration derived? No formal derivation; chosen as large as possible w/o allowing to go negative at the 400 GeV bin boundary. Also, done such to mimic flat priors. 
    • Why are those constraints needed? You have control regions; their constraints are not enough to give a proper pTV dependence? Did consider having NFs per pTV bin, but found to have discontinuities at the bin boundaries.
      • In ATLAS, this is achieved through pTV shape unc within each bin?
    • How avoid that two regions constrain a third etc? There are two linear pTV shape migration unc for four regions (see p25)
      • And for 250/400 GeV boundary? No split of the CRs. But still splitting the SR, so some extrapolation unc might be needed here… 
  • P29 You correlate W+HF and Z+HF (per lepton sub-channel). 
    • Why? Why not Z and W across 0/2 and 0/1L? Account for missing efficiency measurement of tagging algorithm; split in e/mu to account for phase space differences
    • Do you have extrapolation unc considering differences between W and Z? No. 
  • Request: can you publish a pull plot for the most highly ranked NPs? Will be discussed.
  • Did you try an STXS-like diboson measurement? I.e. you only showed the inclusive mu cross-check, but did you also try POI decorrelation in diboson? Yes; did not find the trend found for VH.
  • P34 On the scale variations:
    • Decorrelated between processes, does that mean between V+jets flavour components? Yes, separately for V+LF, V+c etc
    • Correlated across all regions? Yes; also years.
  • P35 
    • NFs are not included here? No, considered in data stat. 
    • Large impact from MC stat. Did you consider heavy-flavour filtered samples or truth tagging technique?
      • LO V+jets are filtered, more difficult for NLO
        • NLO samples are sliced in jet multiplicity etc
        • Also last round with LO samples, MC stat was the leading unc
        • This round also affected by reweighting technique
      • Truth tagging is being considered (detector note on GNN TT: CMS-DP-2022-051)
  • Why not split 1L into 0 and 1 add. Jet? No gain in exp. sensitivity.