STAR Flow, Chirality and Vorticity PWG

[Jiangyong Jia <jiangyong.jia AT stonybrook.edu>]

Hi, Prithwish,

The "official" definition of skewness is as what you say.

According to wikipedia, there are many other Pearson definition of skewness with different nomralization (mode skewness, median skewness). Then we also have "intensive skewness" <(\delta N)^3>*<N>/sigma^2 defined in a recent paper. 

<(\delta N)^3> is can be called third central moment or moment coefficient of skewness.

    I do not see it is a problem, as long as we add a descriptor, e.g.
    name it as normalized skewness (via k_1) then there is no confusion.

Cheers,

Jiangyong

On 10/25/22 11:57 AM, Prithwish Tribedy via Star-fcv-l wrote:

    Dear
      Chunjian,
      
         What you have written is not correct. In STAR we have been
      studying Skewness of distributions for more than a decade. See for
      example:
      
      
      https://arxiv.org/pdf/1004.4959.pdf
      
      https://arxiv.org/pdf/1309.5681.pdf
      
      https://arxiv.org/pdf/2001.02852.pdf
      
      https://arxiv.org/pdf/2101.12413.pdf
      
      
      Skewness = <(\delta N)^3>/\sigma^3 (where, \delta N =
      N-<N> & \sigma is the square root of variance)
      
      What you have is <(\delta N)^3>/<N>^3, they are not
      the same.
      
      
      Again, note that the quantity you have is related to Skewness but
      should be called scaled third order central moment and NOT
      Skewness. (Also, note the difference between moment & central
      moment here.)
      
      
      Where did you find this definition of Skewness? Is it from one of
      the method papers? Do you have a link?
      
      
      Best,
      
      Prithwish
      
      
      
      
      
      On 2022-10-24 15:01, ChunJian Zhang wrote:
      
> Dear Prithwish,
>         
>         
>         Thank you for the comments. Skewness is <(\delta p_T)^3>
>         which is also
>         
>         can be called moments since they are the same when one does it
>         from
>         
>         mean, variance to skewness. Note that kurtosis defined as
>         <(\delta
>         
>         p_T)^4> - 3<(\delta p_T)^2> is different from the
>         moments.
>         
>         
>         Others like <(\delta p_T)^3>/<p_T>^3  and
>         <(\delta p_T)^3>/<(\delta
>         
>         p_T)^2>^3/2 are different normalization ways.
>         
>         
>         So, here we call <(\delta p_T)^3> as skewness is
>         appropriate.
>         
>         
>         Best regards
>         
>         Chunjian
>         
>         
>         
> > On Oct 24, 2022, at 11:53 AM, Prithwish
> >           Tribedy via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:
> >           
> >           
> >           Dear Chunjian,
> >           
> >            Thanks for incorporating my comments. Please note that the
> >           quantity you are showing on slide#8 (lower right plot) is the
> >           ratio of <(\delta p_T)^3>/<p_T>^3 -- this quantity
> >           is not Skewness.
> >           
> >           
> >           In terms of your notations "Skewness" will be something like:
> >           "<(\delta p_T)^3>/<(\delta p_T)^2>^3/2. Since
> >           you're not plotting that so we should not be calling it
> >           Skewness.
> >           
> >           
> >           I think we should refer the quantity <(\delta
> >           p_T)^3>/<p_T>^3 as "Scaled third order moment" or
> >           "Normalized third order moment".
> >           
> >           
> >           On conclusion slide we can say:
> >           
> >           "enhancement in variance and skewness ratios" -->
> >           "enhancement in variance and third order fluctuation ratios"
> >           
> >           
> >           Best,
> >           
> >           Prithwish
> >           
> >           
> >           
> >           On 2022-10-24 09:50, ChunJian Zhang wrote:
> >           
> > > Dear Prithwish,
> > >             
> > >             Thank you for the helpful comments. With including all the
> > >             
> > >             suggestions, please find the new version at
> > >             
> > > https://drupal.star.bnl.gov/STAR/presentations/DNP-2022/Measurement-nuclear-deformation-high-energy-isobaric-96Ru96Ru-and-96Zr96Zr--0
> > >             
> > >             Please find the comments included and addressed as follows:
> > >             
> > > > Side#3:
> > > >               
> > > >               Define "0\nu\beta\beta" somewhere on this slide.
> > > >               
> > > >               "Rarely experimental measurements" --> "Few
> > > >               experimental
> > > >               
> > > >               measurements" or "Rarely explored in experiment”
> > > >               
> > > >             
> > >             Changed
> > >             
> > > > Slide#4: "based on N_{ch}^{offline}
> > > >               with" --> "based on uncorrected
> > > >               
> > > >               tracks (N_{ch}^{offline}) in”
> > > >               
> > > >             
> > >             Changed
> > >             
> > > > Slide#6: Some texts are overlapping,
> > > >               the page number is hidden.
> > > >               
> > > >             
> > >             Changed
> > >             
> > > > Miner & optional comment: the
> > > >               references are not written in
> > > >               
> > > >               conventional  formats (like Zhang and Jia, PRL 128, 022301
> > > >               (2022)).
> > > >               
> > > >             
> > >             Changed
> > >             
> > > > "cancelation" --> "cancellation"
> > > >               
> > > >             
> > >             Changed
> > >             
> > > > It is not clear what you mean by
> > > >               "cancellation expected in
> > > >               
> > > >               non-central collisions". What gets cancelled with what?
> > > >               Also, this
> > > >               
> > > >               is approximately true, right ? Then maybe say "approximate
> > > >               
> > > >               cancellation”
> > > >               
> > > >             
> > >             Added “approximate". The effect from Beta_3 canceled the v2
> > >             ratios.
> > >             
> > > > The 4th bullet is a bit confusing,
> > > >               right? What do you mean by this?
> > > >               
> > > >               It depends on how the size is defined. Larger neutron skin
> > > >               means
> > > >               
> > > >               large size, so there's an apparent contradiction between
> > > >               the 3rd and
> > > >               
> > > >               the 4th bullets.
> > > >               
> > > >             
> > >              added "R0"
> > >             
> > > > Slide#7:
> > > >               
> > > >               "non-linear" --> "Nonlinear" in title and everywhere
> > > >               
> > > >             
> > >             Changed
> > >             
> > > > "reflect nuclear structure" -->
> > > >               "reflects difference in nuclear
> > > >               
> > > >               structure”
> > > >               
> > > >             
> > >             Changed
> > >             
> > > > It's impossible to see what you're
> > > >               plotting on the two right
> > > >               
> > > >               figures. At least write in bigger fonts that you're
> > > >               plotting "Mean
> > > >               
> > > >               ratio" and "Third moment ratio”
> > > >               
> > > >             
> > >             Add large labels
> > >             
> > > > Slide#8: "Study nuclear structure"
> > > >               --> "Study of nuclear structure"
> > > >               
> > > >               "increase in central" --> "increase in central
> > > >               collisions"
> > > >               
> > > >             
> > >             Changed
> > >             
> > > > It is very difficult to read what is
> > > >               plotted on the
> > > >               
> > > >             
> > >             Add large labels
> > >             
> > > > Slide#9: Add "More investigation
> > > >               using STAR data is underway”
> > > >               
> > > >             
> > >             Added
> > >             
> > > > It is not clear what your conclusion
> > > >               is from the data-model
> > > >               
> > > >               comparison on the right. Can you please add a short
> > > >               sentence.
> > > >               
> > > >             
> > >             Add one more sentence.
> > >             
> > > > Slide#10: "identical for Ru and Zr
> > > >               in final state as expected" -->
> > > >               
> > > >               "consistent between Ru+Ru and Zr+Zr as expected"
> > > >               
> > > >               While talking do mention that "as is it driven by final
> > > >               state
> > > >               
> > > >               effects”
> > > >               
> > > >             
> > >             Changed and will follow your nice suggestions.
> > >             
> > > > "variance and skewness" --> You
> > > >               didn't show skewness, maybe say
> > > >               
> > > >               "variance and third order moment”
> > > >               
> > > >             
> > >             We showed the skewness  in the right lower plot on slide 8th
> > >             
> > > > Add "more studies underway" in the
> > > >               last bullet.
> > > >               
> > > >             
> > >             Added
> > >             
> > >             Best regards
> > >             
> > >             Chunjian
> > >             
> > > > On Oct 23, 2022, at 6:43 PM,
> > > >               Prithwish Tribedy via Star-fcv-l
> > > >               
> > > >               <star-fcv-l AT lists.bnl.gov> wrote:
> > > >               
> > > >               Dear ChunJian,
> > > >               
> > > >               Very nice slides. Here are my comments. With these
> > > >               included, I sign
> > > >               
> > > >               off.
> > > >               
> > > >               General comment: some of the fonts you have used are too
> > > >               small.
> > > >               
> > > >               Side#3:
> > > >               
> > > >               Define "0\nu\beta\beta" somewhere on this slide.
> > > >               
> > > >               "Rarely experimental measurements" --> "Few
> > > >               experimental
> > > >               
> > > >               measurements" or "Rarely explored in experiment"
> > > >               
> > > >               Slide#4: "based on N_{ch}^{offline} with" --> "based on
> > > >               uncorrected
> > > >               
> > > >               tracks (N_{ch}^{offline}) in"
> > > >               
> > > >               Slide#6: Some texts are overlapping, the page number is
> > > >               hidden.
> > > >               
> > > >               Minor & optional comment: the references are not
> > > >               written in
> > > >               
> > > >               conventional  formats (like Zhang and Jia, PRL 128, 022301
> > > >               (2022)).
> > > >               
> > > >               "cancelation" --> "cancellation"
> > > >               
> > > >               It is not clear what you mean by "cancellation expected in
> > > >               
> > > >               non-central collisions". What gets cancelled with what?
> > > >               Also, this
> > > >               
> > > >               is approximately true, right ? Then maybe say "approximate
> > > >               
> > > >               cancellation"
> > > >               
> > > >               The 4th bullet is a bit confusing, right? What do you mean
> > > >               by this?
> > > >               
> > > >               It depends on how the size is defined. Larger neutron skin
> > > >               means
> > > >               
> > > >               large size, so there's an apparent contradiction between
> > > >               the 3rd and
> > > >               
> > > >               the 4th bullets.
> > > >               
> > > >               Slide#7:
> > > >               
> > > >               "non-linear" --> "Nonlinear" in title and everywhere
> > > >               
> > > >               "reflect nuclear structure" --> "reflects difference in
> > > >               nuclear
> > > >               
> > > >               structure"
> > > >               
> > > >               It's impossible to see what you're plotting on the two
> > > >               right
> > > >               
> > > >               figures. At least write in bigger fonts that you're
> > > >               plotting "Mean
> > > >               
> > > >               ratio" and "Third moment ratio"
> > > >               
> > > >               Slide#8: "Study nuclear structure" --> "Study of
> > > >               nuclear structure"
> > > >               
> > > >               "increase in central" --> "increase in central
> > > >               collisions"
> > > >               
> > > >               It is very difficult to read what is plotted on the
> > > >               
> > > >               Slide#9: Add "More investigation using STAR data is
> > > >               underway"
> > > >               
> > > >               It is not clear what your conclusion is from the
> > > >               data-model
> > > >               
> > > >               comparison on the right. Can you please add a short
> > > >               sentence.
> > > >               
> > > >               Slide#10: "identical for Ru and Zr in final state as
> > > >               expected" -->
> > > >               
> > > >               "consistent between Ru+Ru and Zr+Zr as expected"
> > > >               
> > > >               While talking do mention that "as is it driven by final
> > > >               state
> > > >               
> > > >               effects"
> > > >               
> > > >               "variance and skewness" --> You didn't show skewness,
> > > >               maybe say
> > > >               
> > > >               "variance and third order moment"
> > > >               
> > > >               Add "more studies underway" in the last bullet.
> > > >               
> > > >               Best,
> > > >               
> > > >               Pritwish
> > > >               
> > > >               On 2022-10-14 15:41, webmaster--- via Star-fcv-l wrote:
> > > >               
> > > > > Dear star-fcv-l AT lists.bnl.gov
> > > > >                 members,
> > > > >                 
> > > > >                 ChunJian Zhang (chun-jian.zhang AT stonybrook.edu) has
> > > > >                 submitted a
> > > > >                 
> > > > >                 material for
> > > > >                 
> > > > >                 a review, please have a look:
> > > > >                 
> > > > >                 https://drupal.star.bnl.gov/STAR/node/61340
> > > > >                 
> > > > >                 Deadline: 2022-10-27
> > > > >                 
> > > > >                 ---
> > > > >                 
> > > > >                 If you have any problems with the review process, please
> > > > >                 contact
> > > > >                 
> > > > >                 webmaster AT www.star.bnl.gov
> > > > >                 
> > > > >                 _______________________________________________
> > > > >                 
> > > > >                 Star-fcv-l mailing list
> > > > >                 
> > > > >                 Star-fcv-l AT lists.bnl.gov
> > > > >                 
> > > > >                 https://lists.bnl.gov/mailman/listinfo/star-fcv-l
> > > > >                 
> > > > >               
> > > >               _______________________________________________
> > > >               
> > > >               Star-fcv-l mailing list
> > > >               
> > > >               Star-fcv-l AT lists.bnl.gov
> > > >               
> > > >               https://lists.bnl.gov/mailman/listinfo/star-fcv-l
> > > >               
> > > >             
> > >           
> >           _______________________________________________
> >           
> >           Star-fcv-l mailing list
> >           
> >           Star-fcv-l AT lists.bnl.gov
> >           
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> >           
> >         
>       
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