HF PWG Meeting Minutes by Zhenyu - 2014/04/24

1) J/psi from Au+Au 200GeV Run11 MB - Wangmei
Wangmei presented systematic uncertainty estimation. Questions raised on the details of the study. The biggest concern was on the deviation at low pT between the published Run10 results and the Run11 results in this analysis. Wangmei asked how to move forward. Daniel suggested to concentrate on 39 and 62 GeV results for publication, while Zhenyu argued that such a discrepancy must be understood before considering 39/62 GeV results for publication. Questions were also asked on the yield exaction, among other things. Wangmei promised to give a update in the PWG meeting next week.

Action items:
1. slide 3, add the definition of acceptance correction
2. slide 4, list the exact cuts used for this study
3. slide 9, explain how the EM clusters are reco'ed
4. slide 10, add plots for every pT bin, plot chi2 from the fit as a function of smearing factor, 
                  change the lower and upper limit of the fit and count range separately and report the change in the yield
5. slide 11, apply the radiative decay correction and assign half of the correction as a symmetric uncertainty
6. slide 13/14, in order to understand the difference between Run10 and Run11,
                  check whether run10 used BSMD cuts or not, and if so, try it in  the current analysis
                  check how exactly run10 exacted the J/psi yield and follow the same approach in the current analysis

2) D* from p+p 500 GeV Run11 HT - David
David gave a report about new studies that have been done for this analysis: require pT>5 GeV/c for trigger particle due to the difference in the trigger efficiency between data and embedding at lower pT region. Still the cross sections from MB and BHT1 data do not agree for D* pT=6.5 GeV/c bin, which will need further investigation. David also reported that the exact D* yield is sensitive to the D* width (whether it is a free parameter in the fit or is fixed according to Toy MC). Daniel suggested to compare the fitted width as a function of D* pT between data and toy MC, and fit the width in data as a function of pT and using the results to constrain the yield exaction. David also reported that he found from embedding that the VPD efficiency increases versus reference multiplicity, opposite to what was observed for 200GeV, which will need further investigation by e.g. looking at BBC triggered events. The last item discussed was about inclusive pion spectra, for which results from UA1 p+pbar 500GeV is 28% lower than STAR, right now this is taken as a systematic uncertainty. Zhenyu suggested to compare Pythia with p+pbar 500 GeV and p+p 510 Gev, and use the exact rapidity range as done in the UA1 and STAR analyses to see if one can reproduce this 28% difference.

Action items:
1. understand difference in D* yield between MB and HT data
2. use data itself to constrain the D* width in the yield exaction
3. understand/confirm why VPD efficiency increases with reference multiplicity
4. understand the 28% difference in inclusive pion yield between UA1 and STAR

3) D meson from p+p 200 GeV Run12 HT - Hao
Hao reported his own nSigma_dEdx results and compared with Xiaozhi's. The difference is not understood. The pion HT trigger efficiency is exacted and is found to be higher than the one quoted in Yichun's thesis. The difference is not understood. 

4) J/psi polarization from p+p 500 GeV Run11 HT - Barbara
Barbara updated her analysis. She removed the towers in data for which DSMDAC>0.1*ADC0 and removed these towers from embedding. She found that the points around theta~0 are significantly higher than the rest, which could be due to biased efficiency correction or uncorrected continuum background. For now she excluded these points from the fit, but she will look into this. She asked whether she should show the fit results in her QM2014 poster, and it is agreed that these should not be included.

5) Upsilon from U+U 193 GeV Run12 HT - Robert
Robert looked into the consistenty between different E_cluster/p sample, and found the difference is at 1.6sigma level. He estimated the statistical uncertainty of the Upsilon yield by emsemble tests and found that the uncertainty estimation from fitting is not biased. He studied E_cluster/p in different samples with different eID cuts, and proposed a way to estimate the central and uncertainty of the efficiency, which is accepted by the group. Finally, he presented R_AA with the updated statistical and Nbin uncertainties. It is suggested to report upper limit instead of a central value for the 0-10% centrality bin, due to the limited signal significance. Q

Action item:
1. Robert will ask Hui and bulkcorr group to see if they have new Glauber model tuned to UU data, so that he could use their new Nbin and Npart values.
2. Zhenyu will send to the group the numbers he is using, based on Hiroshi's study in 2013 when he left. (click this)