From Erik Brubaker *: We should do/study it. +: We should think about it and seriously consider doing/studying it. -: Probably not worth spending extra time on. +Optimize cut on 4th jet et (i.e. half jet for 3.5 jet events). -SLT jet corrections (in progress, probably not feasible). +Optimize W mass constraint. Is PDG value the right thing here, or can we scan over some range and choose something more experimentally based? Mean of dijet W mass is not 80.41. *Use Breit-Wigner instead of Gaussian shape for W and top lineshapes. How to do this in a chi2? *Use top width of 1.5, not 2.5. Easier to explain even if Gaussian approximation is more important than actual width used. Check what the generators use; be consistent. *Reoptimize chi2 cuts (in progress). -Probabilistic treatment of tags<->j-p assignment (takes lots of study, not feasible). -Any better signal template parameterization? +Fit background components separately in likelihood? +Better fits to background templates. In particular, the mistag template is a collection of weighted events and the Poisson statistics assumed in a binned likelihood fit don't apply. Similarly for the combined template, used in our current approach. Because of this, it's not clear what normalization to give the weighted templates. The chi2/ndof is affected also (it's currently quite low). +For PDF uncertainty, weight background template as well? (Lots of work, probably not much reward.) *Re-evaluate the b-tagging systematic. +Better approach/prescription for getting 68% coverage than scaling uncertainties? From Jean-Francois + Better estimate of the MC statistics uncertainty (re-extract machinery from fluctuated templates) * Try combining subsamples based on total uncertainty * For 2-tag mistag background, a more realistic shape would be 1 real tag+1 mistag (instead of 2-mistag) * Take correlation in the background into account Pekka Sinervo Check out whether whether we would gain significantly from use of an enhanced SVX tagging algorithm. A study of a combined SecVTX+JetProb tagger by Stan Lai (CDF 6874) would suggest a 15-20% increase in b-tags with only a modest increase in fake tags. This would result in something like a 7-10% improvement in statistical precision, perhaps more if we significantly increase our double-tag yield. Of course, we would need to make sure that the studies done in 4.11 are repeated with 5.3. This is a different strategy than using a probabilistic approach to b tagging in the fitting (which I agree is not feasible).