STAR Flow, Chirality and Vorticity PWG

[Niseem <niseemmagdy AT yahoo.com>]

Dear ShinIchi,

Thanks for the nice point.
I found a scaling factor in my plotting macro for the 70-80. I correct that typo.

Please find the updated slides at,

https://drupal.star.bnl.gov/STAR/node/55552

Thanks,
Niseem

On 7/9/21 8:08 AM, ShinIchi Esumi via Star-fcv-l wrote:

      Dear Niseem

Thanks for the answers, I'll wait for your next pwg presentation. 

The error bars that we see on the correlation functions (G2 plot), which is only visible 

for peripheral in both delta_phi (on page 3) and delta_eta (on page 4), do look strange 

to me, if this is meant for statistical error, just because of the point-to-point “statistical” 

fluctuations between neighboring data points are much smaller than the error bars. 

Since you do not have any specific pT selection (0.2 - 2.0 GeV/c), so that the statistical 

errors should not be visible anyway even in peripheral, isn’t it? Or are they systematic 

error, in stead? 

Best regards, ShinIchi

On Jul 9, 2021, at 5:42, Niseem via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Hi ShinIchi,

Thanks for your nice comments, please find the updated slides at the same link,

https://drupal.star.bnl.gov/STAR/node/55552

For your comments,

It could be informative, if you could plot "v2,3,4 vs centrality” on top of the plot “a2,3,4 vs centrality” at the bottom-left of page 3 with some scaling constant (better to be common for all the orders) in order to show the centrality dependent shape (which does not have to be in the talk, maybe in the analysis note later). 

>> I added a plot to the backup slide showing the v_n and the a^{p_T}_n.  I will include this in our analysis note later.

  The top-left formula of page 3 does include offset parameter a0^pT, which also seems to show a possibly interesting centrality dependence, that you could consider showing (maybe in the analysis note...) 

              >> I showed this before in the
                  PWG meeting. I will include this in the analysis note
                  which I’m working on it now.
               
              I was still thinking about the point I
                  raised yesterday in the PWG related to above points,
                  how we can define the an^pT parameter to be able to
                  compare this with vn. Since G2 is defined as pT square
                  after subtracting the baseline that is the average pT
                  square, so that the a0^pT parameter is a kind of
                  measure of "non-flow" with a dimension of (GeV/c)^2
                  and an^pT parameters are the measure of "flow" with a
                  dimension of (GeV/c). 
               
              G2’ = G2 / baseline = (pT_correlation
                  - baseline) / baseline
               
              If we think about using modified G2’
                  as above in stead of your current G2, one can plot (1)
                  an^pT/<pT>, which is more comparable definition
                  to the "non-flow subtracted vn”, and/or (2)
                  an^pT/sqrt(baseline + a0^pT), where the baseline is
                  the average pT square, this is could even be more
                  reasonable to be compared with vn measurement. 
              In this definition, (1)"non-flow
                  subtracted vn" is even larger the other one (2), which
                  is similar to the difference between reference fitting
                  (or c1_subtraction) and template fittings for the
                  small system vn analysis. 
              >> I will discuss this point
                  with Claude Pruneau and I will
                  update the PWG. 
               
               
              How is sigma_delta_eta(G2) defined? Is
                  this defined as RMS or Gaussian fitting of
                  G2(delta_eta) distribution? How did you treat the
                  baseline that we see in G2 as a function of delta_eta?
                  I remember we’ve discussed this sometime ago in the
                  PWG, but not yesterday. The baseline could also be
                  defined from a0^pT parameter from azimuthal fitting at
                  large delta_eta or even in 2D... The sigma (or RMS)
                  would largely be affected by the method how we define
                  the baseline, so we need to make sure what we do and
                  what we observe. 
              >> (1)  sigma_delta_eta(G2)
                  = RMS, I added this to the slides
                  >> (2) The baseline is defined from the from
                  azimuthal fitting at different delta_eta
                  >> (3) The baseline decrease with increasing the
                  Nch (i.e. it will not impact the linear increase of
                  the  RMS with Nch)
              >> (4) Now I’m working with the
                  SBU and WSU groups on a paper proposal and we will
                  include all this information in our analysis note
               
              Related to this, several different
                  cuts on delta_phi to look at delta_eta shape, as well
                  as, several different cuts on delta_eta to look at
                  delta_phi shape, would be important, 2D analysis could
                  even be better as we discussed at the end of PWG
                  yesterday.
              >> Now I’m working with the SBU
                  and WSU groups on a paper proposal and we will include
                  all this information in our analysis note.

Thanks,
Niseem

On 7/8/21 2:12 AM, ShinIchi Esumi via Star-fcv-l wrote:

Dear Niseem

It could be informative, if you could plot "v2,3,4 vs centrality” on top of the 
plot ”a2,3,4 vs centrality” at the bottom-left of page 3 with some scaling 
constant (better to be common for all the orders) in order to show the 
centrality dependent shape (which does not have to be in the talk, maybe 
in the analysis note later). 

The top-left formula of page 3 does include offset parameter a0^pT, which 
also seems to show a possibly interesting centrality dependence, that you 
could consider showing (maybe in the analysis note...) 

I was still thinking about the point I raised yesterday in the PWG related to 
above points, how we can define the an^pT parameter to be able to compare 
this with vn. Since G2 is defined as pT square after subtracting the baseline 
that is the average pT square, so that the a0^pT parameter is a kind of 
measure of "non-flow" with a dimension of (GeV/c)^2 and an^pT parameters 
are the measure of "flow" with a dimension of (GeV/c). 

G2’ = G2 / baseline
      = (pT_correlation - baseline) / baseline

If we think about using modified G2’ as above in stead of your current G2, one can plot 
(1) an^pT/<pT>, which is more comparable definition to the "non-flow subtracted vn”, 
and/or (2) an^pT/sqrt(baseline + a0^pT), where the baseline is the average pT square, 
this is could even be more reasonable to be compared with vn measurement. 
In this definition, (1)"non-flow subtracted vn" is even larger the other one (2), 
which is similar to the difference between reference fitting(or c1_subtraction) and 
template fittings for the small system vn analysis. 

How is sigma_delta_eta(G2) defined? Is this defined as RMS or Gaussian fitting 
of G2(delta_eta) distribution ? How did you treat the baseline that we see in G2 as 
a function of delta_eta? I remember we’ve discussed this sometime ago in the PWG, 
but not yesterday. The baseline could also be defined from a0^pT parameter from 
azimuthal fitting at large delta_eta or even in 2D... The sigma (or RMS) would largely 
be affected by the method how we define the baseline, so we need to make sure 
what we do and what we observe. 

Related to this, several different cuts on delta_phi to look at delta_eta shape, as well 
as, several different cuts on delta_eta to look at delta_phi shape, would be important, 
2D analysis could even be better as we discussed at the end of PWG yesterday. 

Best regards, ShinIchi

> On Jul 8, 2021, at 4:41, webmaster--- via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:
>
> Dear star-fcv-l AT lists.bnl.gov members,
>
> Niseem Magdy Abdelwahab Abdelrahman (niseemmagdy AT yahoo.com) has submitted a  
> material for a review, please have a look:
> https://drupal.star.bnl.gov/STAR/node/55552
>
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