HF-PWG minutes 2017/01/05

 1) J/psi v2 in U+U collisions - Alena Harlenderova
a. Check why the non-flow contribution for 0-80% centrality bin is closer to that for the 40-80% centrality bin instead of 0-10% and 10-40% bins for the lowest pT bin. 
b. Check why the non-flow contribution seems larger than the published results.
c. J/psi v2 in the 0-2 GeV/c bin is different for MB and HT triggered events. Need to check if there is any centrality-dependent trigger bias.

2) Non-prompt J/psi in Au+Au collisions - Bingchu Huang
a.Currently, the Run14 templates are used to fit Run16 data. However, the DCA distributions of single tracks for Run14 and Run16 are different. Need to check the influence of this diffference on the resulting templates. If the influence turns out to be negligible, one can combine the raw ctau distributions from Run14 and Run16 and then do the fit. This should improve the stability of the fits given the low statistics in each dataset.
b. Need to estimate the uncertainties due to the noramlization of the mixed-event background, and residual contributions from ccbar decays.

3) J/psi event activity in Run12 pp 200 GeV - Bingchu Huang 
a. For the cross-section measurement, need to check the raw yields used in the preliminary and current resutls for the first three pT bins. The second bin jumps up quite a bit. Also need to correct the bin width by shifting data points horizontally instead of vertically.
b. Slide 7: the Nch = 0 bin after unfolding is excluded now. This is different from the ALICE approach, in which only events with at least one reconstructed tracklet are used.
c. Slide 10: show the ratio between PYTHIA and data.
d. Slide 11: uncertainties associated with fitting need to be considered, for example the amount of smearing, background shape, etc. For the uncertainty on the GEANT simulation of trigger bias, the PA stated that it is smaller than the uncertainty coming from different generator tunes. It will be nice to include this in the AN.
e. Try different prior and different unfolding method 
d. Slide 14: need to understand the factor of 2 difference between data and NBD fit at Nch = 1

4) Upsilon in Run15 pp and pA collisions - Zaochen Ye
a. The width of the Jpsi mass peak is about 90 MeV while it is about 40 MeV for the dimuon case. Both analyses use primary tracks. Need to investigate why the resolution is particularly bad for electrons.
b. Improve fits to the invariant mass: rebinning, DY shape, etc