STAR Flow, Chirality and Vorticity PWG

[tc88qy <tc88qy AT rcf.rhic.bnl.gov>]

Hi Diyu and all
   First of all, I want to bring it up that every people at STAR have 
the right to express his/her concern about any analysis.
I also working on the same data and the same topic. The student Dandan 
and I also did the J/psi polarization measurement by using exact the 
same data set. The only different between spin alignment and 
polarization measurement is the different reference z-axis. Dandan's 
results will be present at the coming quark matter conference and got 
approved by HP pwg.
   This two analysis have very similar method.  The concern I bring it 
up because we have encountered such problem in the J/psi polarization 
measurement. And from you comparison between crystal-ball and guassian 
function, it already prove that the yield extraction will affect the 
final results. By just changing the signal function, the rho00 central 
value changes are comparable with statistic uncertainty in Ru+Ru 40-80%.
   I did not know how did you do the fitting. The experience we have is 
that J/psi shape (crystal-ball function) can not take as a free 
parameter in the fitting.
   The fitting range of 2.6-3.6 GeV/c is a litter big narrow. There is 
about 20-30% of J/psi yields are below 3 GeV/c2. Like in the pp system, 
J/psi bin counting range is 2.7-3.3 GeV/c2 at STAR. You should extend 
your fitting range to lower mass range, so that it will have a better 
control on residual background.

Qian Yang

On 2023-08-31 18:11, dshen via Star-fcv-l wrote:
> Regardless of wether we should show J/Psi at QM, as the author I feel
> my duty to defend the reliability of my plot.
> So I checked with crystalball function instead of a simple Gaussian
> function. The variation is small.
> I acknowledge this plot can be improved in the future, but I don't
> think the physics message could be wrong (no J/Psi spin alignment
> relative to ZDC plane is observed).
> I am a careful people, no more no less.
>
> Thanks,
> Diyu
>
>
> On 2023-08-28 23:41, dshen wrote:
> > Dear Conveners,
> >
> > Here are our preliminary request for J/Psi spin alignment measurement
> > relative to 1st order ZDC event plane.
> > https://drupal.star.bnl.gov/STAR/system/files/JPsiPreliminaryRequest.pdf
> >
> > Thanks,
> > Diyu
> >
> > On 2023-08-23 14:24, Sooraj Radhakrishnan via Star-fcv-l wrote:
> > > Hi Gavin,
> > >    These are nice results and quite interesting. I have a question on
> > > the rapidity dependence. The observed rapidity dependence is quite
> > > strong, and also the value of rho_00 for y < 0.5 is quite close to
> > > 1/3. I see that for efficiency correction you use a flat distribution
> > > in rapidity. At these energies is this a reasonable distribution to
> > > use? Do you have any systematics on the impact of the rapidity
> > > distribution used on efficiency evaluation?
> > >
> > > For the theory calculation, is this the same model as in the nature
> > > paper? Could you add the reference? Are there any assumptions in
> > > getting the rapidity dependence? Why wouldnt we see the 
> > > spin-alignment
> > > at mid-rapidity, and see large values at forward rapidity? Shouldn't
> > > the physics causing spin alignment be present at mid-rapidity too? I
> > > see on your S33 the explanation that the values are linked to motion
> > > of the particle. Is this a trivial kinematic effect? The px, py, pz
> > > here are in lab frame?
> > >
> > > thanks
> > > Sooraj
> > >
> > > On Thu, Aug 17, 2023 at 9:06 PM Gavin Wilks via Star-fcv-l
> > > <star-fcv-l AT lists.bnl.gov> wrote:
> > >
> > > > Dear FCV Convenors,
> > > >
> > > > My preliminary request for QM2023 φ-meson global spin alignment
> > > > analysis can be found here:
> > > https://drupal.star.bnl.gov/STAR/system/files/userfiles/6551/PreliminaryRequest_QM2023_FoldedRapidity.pdf
> > > > Best,
> > > > Gavin_______________________________________________
> > > > Star-fcv-l mailing list
> > > > Star-fcv-l AT lists.bnl.gov
> > > > https://lists.bnl.gov/mailman/listinfo/star-fcv-l
> > >
> > > --
> > >
> > > Sooraj Radhakrishnan
> > >
> > > Research Scientist,
> > > Department of Physics
> > >
> > > Kent State University
> > >  Kent, OH 44243
> > >
> > > Physicist Postdoctoral AffiliateNuclear Science Division
> > > Lawrence Berkeley National Lab
> > > MS70R0319, One Cyclotron Road
> > > Berkeley, CA 94720
> > > Ph: 510-495-2473 [1]
> > >
> > > Email: skradhakrishnan AT lbl.gov
> > >
> > >
> > > Links:
> > > ------
> > > [1] tel:%28510%29%20495-2473
> > > _______________________________________________
> > > Star-fcv-l mailing list
> > > Star-fcv-l AT lists.bnl.gov
> > > https://lists.bnl.gov/mailman/listinfo/star-fcv-l
>
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