STAR Flow, Chirality and Vorticity PWG

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

Hi Diyu and all

I did a quick check on the impact of yield extraction. Please look at 
the slides:
https://drupal.star.bnl.gov/STAR/system/files/Yield_extraction_check.pdf
These slides is just an example. If the yield extraction is not down 
properly, we can easily fake out or overwhelmed a signal.
Hope this will help to explain the point I'm saying: it is all about 
details.

Qian Yang

On 2023-09-02 00:04, dshen wrote:
> Hi Qian,
>
> Sure, no problem, any specific and scientific comments/questions are
> always welcome.
> Regarding to the crystalball fitting, I firstly fit the costheta*
> integrated invariance mass distribution, in this fitting there are
> limitations for J/Psi shape, like the center mass range. Then I fixed
> the J/Psi shape in each costheta* bin to extract the yields and
> backgrounds.
> Regarding to the fitting range, I couldn't check it for now because I
> am on the way to QM with my old laptop. All the materials are on my
> working computer. Form you experience, can you estimate how large this
> effect will be? Will it lead to different conclusion if consider the
> current error bar?
>
> Best,
> Diyu
>
>
>
> On 2023-09-01 21:02, tc88qy wrote:
> > 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
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> > >
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