STAR Flow, Chirality and Vorticity PWG

[arkadij71 <arkadij71 AT gmail.com>]

Dear ShinIchi,

Thank you very much for your comments, questions and suggestions.
Kaons are very interesting and by doing the comparison with published
results we saw the same strong pt dependence of v2(K+)/v2(K-) ratio
at low pT - but statistics of BES-I are too low to study this effect in
detail. We think that the charged kaons should be analysed together
with KShort - as in the STAR published results one sees very interesting
differences, please see the link to the compilation.  We know that there
are some 10-15% differences between v2 of charged kaons and Kshort at
LHC - if we trust ALICE results. It looks like  the same difference one
see in published STAR results - it is 5-6% at 39-62.4 GeV and it is
smaller at lower energy.
https://drupal.star.bnl.gov/STAR/system/files/kaons.pdf
We will come back to PWG with new checks for kaons.

Our main goal for particle-antiparticle analysis was the v3 of protons
and antiprotons and  we chose new run18 27GeV data - only because of
the high statistics and energy - where we see a rather big difference in v2.
The preliminary v3 results were controversial - in 2014 one STAR analysis
saw the difference between v3 of protons and antiprotons, part of 2019
- the difference was not visible in the other analysis and we happy, that
Now we all see this difference in v3 and it looks in some way similar to
v2 of protons and antiprotons.

Concerning your points for v2 of K+ and K- difference at high energies -
we checked the STAR published results for 10-40% at 39 GeV and 62.4 GeV
from Phys. Rev. C 93 (2016) 14907
and we do not see that the integral v2 value can be slightly negative -
it is really close to zero, but it has positive values at lower pT -
please see link to kaons.pdf
we also provide the same comparison for 10-40% from our analysis and as
we cut at pT < 1.5 GeV - we are getting a slightly positive signal, see page 7-8
in kaons.pdf


Following your request we removed all hight pT kaon points from all plots
and we posted  a new version of the presentation.
https://drupal.star.bnl.gov/STAR/system/files/ICPPA2020_Parfenov.pdf
We hope for your help and
suggestions very much as the conference in Moscow will start tomorrow.


Thank you very much.
With best regards

Petr, Alexander, Alexey, Grigory and Arkadiy

On Sun, Oct 4, 2020 at 3:37 AM ShinIchi Esumi via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Dear Petr, Alexander, Alexey, Grigory and Arkadiy

We are not asking whether the data is consistent with the previous data, 

as you have already shown the comparison in the PWG. The kaon+/- ratio 

(difference) data are closer to proton/anti-proton at lower pT and are closer 

to the pi+/- at higher pT, which could be real based on some physics. We are 

just asking whether you are sure about the contamination or other experimental 

effects which could be affecting the ratio in pT dependent way in your own 

analysis, let’s just do not trust the previous data too much. Looking at the PRC88 

Fig.11 panel(b) lower delta_v2 plots, I see the similar effect especially around 

the beam energy of 10-30GeV and the major/important effect (change) would 

be more at lower pT getting closer to proton difference. 

You are showing only for 27GeV data, since this is new from run18? Have you 

also looked at the similar pT dependent ratio or difference for other beam energies? 

nSigma cut from tpc dedx is defined in momentum dependent way (right?), however 

your m2 cut is not done in the same way (common for all momentum), so the inclusion 

of TOF does not help much in this sense, where m2 width would get wider caused by 

the momentum resolution at high pT. If you have any doubt in the kaon data as you 

have removed the higher pT points from the ratio, I would do the same for all the 

other figures, not just removing the ratio plots. 

I've also realized that your data delta_vn vs energy data show always positive 

finite delta_v2 for kaon up to 60GeV 0-60% centrality, while it went slightly negative 

or very close to zero around 40GeV or above in the energy dependence plot 

(PRC88 Fig.21 and PRL110 Fig.2 for 0-80%, PRC93 Fig.7 for 10-40%), can you 

say for sure this difference is caused by your different centrality choice or somewhat 

different mean pT coming from the different ways of PID, where your systematic 

error is quite small? 

Best regards, ShinIchi

On Oct 4, 2020, at 4:55, arkadij71 <arkadij71 AT gmail.com> wrote:

Dear   ShinIchi   and  Jiangyong ,
Thank you very much for the comments. Our pid v2 results are fully consistent
with published STAR v2 pid results from
Phys. Rev. C 93 (2016) 14907
Phys. Rev. C 88 (2013) 14902
Phys. Rev. Lett. 110 (2013) 142301
for 0-10%, 10-40% , 40-80% and 0-80% for
all points in collision energy as it was demonstrated. It means that STAR published
results also show such pt dependence for the difference between v2 of K+
and K- for all bins in centrality and collision energy.
We think that the STAR published results are correct as they were obtained
with more probably robust procedure for kaon/pion separation using m2 rotation method.
We are using the stringent cut on mass2 for particle separation. However, we
are getting consistent results for v2 with published ones.
We understand your concern and worry about the particle purity and our students
Alexey Povarov and Alexander Demanov are started to do the homework - however, 

we are not able to finish it before the
conference and therefore we proposed to limit pt range for kaons in the figure on
slide 11 to pt range - where pions and kaons are very well separated. We will come
back with the results of the homework soon. If you request to remove slide 11 from the conference
presentation we agree to do it.
Concerning the systematics, the biggest source is coming from the results for different
eta gaps. The influence of different PID cuts was found to be small as it was shown.
We plan to check the rotation mass2 method as an additional cross-check.

With best regards
Petr,  Alexander , Alexey, Grigory, Arkadiy,  

On Fri, Oct 2, 2020 at 4:51 PM ShinIchi Esumi via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Dear Petr
One more point that if you think the ratio (or difference) does have issues,
Then we should also be worrying about individual vn for k+ and k- as well.

After you store all your preliminary plots in the
special drupal area for the preliminary location with necessary information at :
https://drupal.star.bnl.gov/STAR/pwg/bulk-correlations/bulkcorr-preliminary-summary
then I would approve your talk.
Best regards, ShinIchi

> On Oct 2, 2020, at 22:14, ShinIchi Esumi via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:
>
> Dear Petr
> Concerning on the same point on page 11 as Jiangyong mentioned, we’ve asked you
> to make sure the sign change of kaon vn ratio (and difference) at higher pT is real or
> it’s coming from pion contamination etc, which we did not hear you back on this particular
> issue, but it seems that you have now excluded the higher pT point from the plot, although
> you’ve shown us in the collaboration meeting up to higher pT and it was consistent with
> our previous publication, which might have the same issue as well, then we would need to
> correct the previous data, if this is really the case. Does that mean you do now think they
> are indeed affected by some PID problem at high pT? Since you’ve changed the plot in
> the last minutes after the last PWG, I would think we should be excluding these ratios (and
> differences) plots at least for kaon as a function of pT, until you explain us with more details
> especially in terms of the sign change trend with systematic error including PID purity etc.
> What do you think?
> Best regards, ShinIchi
>
>> On Oct 2, 2020, at 20:59, Jiangyong Jia via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:
>>
>> Hi, Grigory and Petr,
>>
>> The slides are nicely written, I don't have major comments on the structure of the talk.
>>
>> I have one question that I asked during Petr's presentation a couple weeks ago.
>>
>> Slide 11 when you show the difference and ratios between particle and antiparticles, the errors are extremely small.
>> Do you assume the systematic uncertainty mostly cancel?  What about the purity and efficiency of PID cut, I assume
>> they will not cancel (yield of particles are anti-particles are different at low energy)
>>
>> thanks,
>>
>> Jiangyong
>>
>> n 10/2/20 6:47 AM, Grigory Nigmatkulov via Star-fcv-l wrote:
>>> Dear Conveners,
>>>
>>> Please take a look at the Petr Parfenov's slides and sign off you have no questions.
>>> The conference starts on Monday.
>>>
>>> Best regards,
>>> Grigory, Arkadiy and Petr
>>>
>>> On Wed, 23 Sep 2020 at 20:53, webmaster--- via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:
>>> Dear star-fcv-l AT lists.bnl.gov members,
>>>
>>> Grigory Nigmatkulov (nigmatkulov AT gmail.com) has submitted a material for a 
>>> review, please have a look:
>>> https://drupal.star.bnl.gov/STAR/node/52191
>>>
>>> ---
>>> If you have any problems with the review process, please contact 
>>> webmaster AT www.star.bnl.gov
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