STAR Flow, Chirality and Vorticity PWG

["Wang, Fuqiang" <fqwang AT purdue.edu>]

Jagbir,

Thanks for the plot. So you interpret the leftmost points as from CME and 
extract a CME fraction from it. What physics would you interpret the 
rightmost data points where the signals appear negative?

Best regards,
Fuqiang



> -----Original Message-----
> From: jagbir <jagbir AT rcf.rhic.bnl.gov>
> Sent: Tuesday, December 15, 2020 8:55 AM
> To: Wang, Fuqiang <fqwang AT purdue.edu>
> Cc: STAR Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>; 
> star-cme-
> focusgroup-l AT lists.bnl.gov; aggarwal AT pu.ac.in
> Subject: Re: [Star-fcv-l] FCV PWG meeting, 18/Nov/2020 (Wed) 9:30am (New
> York time zone)
> 
> Dear Fuqiang,
> 
> Please find my replies below:-
> 
> ------------------------------
> 
>       1. because your selection is predominated by statistical fluctuations 
> yet
>       you're applying a cut on those statistical fluctuations.
> 
>       Our selection is not by statistical fluctuations but based on 
> fractional
>       Dumbbell charge separation in the data. However, similar type of 
> charge
>       separation can be due to statistical fluctuations, to account for that
>       we are using charge reshuffle. Now we are having about 160M events.
> It is
>       seen that observed delta gamma in the data is large beyond statistical
>       fluctuations than those of charge reshuffle for  the top 0-20%
> Db+-max
>       bins. The plot you asked is attached here with email.
> 
> ------------------------------
> 
>       2. I mean the max Dbmax_shuffle bin is a random collection of events 
> from
>       this centrality bin.
> 
>       The max Dbmax_shuffle bin is not a random collection of events from
>       this centrality bin. As explained earlier we generated charge 
> reshuffle
>       events by reshuffling charges of partices in the real data in a given
>       collision centrality. So, charge reshuffle events are completely 
> independent
>       sample from real data sample in  given centrality though number of
>       positive/negative charged partciles are kept same in each reshuffle 
> event
>       corresponding to real data event. Again  Dbmax_shuffle bins are made
>       according to the fractional Dumbbell charge separation in the charged
>       reshuffle event sample for a given collision centrality.
> 
> ------------------------------
> 
> Thank you,
> Jagbir Singh
> 
> 
> On 2020-12-14 22:46, Wang, Fuqiang wrote:
> > Jagbir,
> >
> > Please see my replies below.
> >
> > Best regards,
> > Fuqiang
> >
> >
> >
> >> -----Original Message-----
> >> From: jagbir <jagbir AT rcf.rhic.bnl.gov>
> >> Sent: Monday, December 14, 2020 11:18 AM
> >> To: Wang, Fuqiang <fqwang AT purdue.edu>
> >> Cc: STAR Flow, Chirality and Vorticity PWG
> >> <star-fcv-l AT lists.bnl.gov>;
> >> star-cme-
> >> focusgroup-l AT lists.bnl.gov; aggarwal AT pu.ac.in
> >> Subject: Re: [Star-fcv-l] FCV PWG meeting, 18/Nov/2020 (Wed) 9:30am
> >> (New York time zone)
> >>
> >> Dear Fuqiang,
> >>
> >>     Please find my replies below:-
> >>
> >> 1.   I understand your motivation doing that but I don't agree this is
> >> the right approach
> >>     (I think it causes biases).
> >>
> >>     Please let me know why this is not the right approach and what
> >> kind of biases you meant.
> > [Fuqiang Wang] because your selection is predominated by statistical
> > fluctuations yet you're applying a cut on those statistical
> > fluctuations.
> >
> > Can you plot (data-chrgR. Bkg) and (Correlated bkg) vs (Dbmax bin) on
> > slide 25 so we can see the details better?
> >
> >>
> >>
> >> 2.   you have only one point left. Your f_cme is basically the
> >>       (Delta gamma of those events in that Dbmax bin)
> >>       - (Delta gamma of a random collection of events in the same
> >> centrality bin which happen
> >>       to have the same Dbmax_shuffle bin)
> >>       - (Delta gamma of those same random events calculated after the
> >> charges are shuffled)
> >>       Do I understand it correctly?
> >>
> >>     If only one point is left as you wrote, please see the
> >> explanation
> >> below:
> >>
> >>     Here, there is nothing like random collection of events in the
> >> same centrality bin.
> > [Fuqiang Wang] I mean the max Dbmax_shuffle bin is a random collection
> > of events from this centrality bin.
> >
> >>     We select events depending on Db+-max i.e., depending on the
> >> back-to-back charge
> >>     separation fDbCS = Db+-max-1. As you wrote only one point, in
> >> that case it is the
> >>     top 10% Db+-max events corresponding to maximum back-to-back
> >> charge separation events.
> >>     It is similar to selecting events in particular collision
> >> centrality depending on
> >>     the impact parameter or event multiplicity. As we have selected
> >> in the data top 10%
> >>     Db+-max corresponding to maximum back-to-back charge separation
> >> events, in  same way
> >>     we select events from charge reshuffle in the same collision
> >> centrality for top 10%
> >>     Db+-max(here Db+-max of charge reshuffle) corresponding to
> >> maximum
> >> back-
> >> to-back
> >>     separation. Now we get delta_gamma_data of real data events
> >> corresponding to top
> >>     10% Db+-max of data and delta_gamma_sta of charge reshuffle
> >> events corresponding to top
> >>     10% Db+-max of charge reshuffle for a given collision centrality
> >> which gives
> >>     us delta_gamma due to statistical fluctuations. Now for
> >> correlated background we
> >>     look for real events in the data corresponding to the top 10%
> >> Db+-max
> >>   of charge
> >>     reshuffle in a given centrality and get delta_gamma_cor from
> >> those real
> >>     data events.
> >>
> >>     Now the f_CME is obtained as
> >>
> >>     f_CME = N1*(delta_gamma_data - delta_gamma_sta -
> >> delta_gamma_cor)/(delta_gamma_data * N)
> >>
> >>     Where N1 is number of events in top 10% Db+-max and
> >>     N is total number of events in a given collision centrality.
> >>
> >> Thank you,
> >> With regards,
> >> Jagbir Singh
> >>
> >> On 2020-12-14 10:32, Wang, Fuqiang wrote:
> >> > Jagbir,
> >> >
> >> > Thanks for your answers.
> >> >
> >> > To your questions:
> >> >> Please clarify the following
> >> >>       Of course you've also removed the large charge-shuffle
> >> >> background which is basically
> >> >>       an autocorrelation effect (sort to speak) due to the Dbmax
> >> >> (and
> >> >> Dbmax_shuffle)
> >> >>       selection bias.
> >> > I was just saying it in passing, referring to the fact that you're
> >> > largely selecting on statistical fluctuations and trying to remove
> >> > the auto-correlation effect by shuffling. It wasn't a question.
> >> >
> >> >>       Please explain the following:
> >> >>       So is your finite signal really due to the difference
> >> >> between the average of ratios
> >> >>       and the ratio of averages (or perhaps also due to residual
> >> >> effect from shuffling)?
> >> > I was referring to the fact that if you had a single Dbmax bin (i.e.
> >> > taking average first and then ratio) then you'd get zero signal by
> >> > definition. You now have 10 bins and take ratios first in each bin
> >> > and then take average of the ratios, and get a positive signal.
> >> > During the focus meeting discussion, it was made clear that your
> >> > analysis required multiple Dbmax bins, not taking average of all
> >> > bins, but only those with Delta gamma > 0. So now I think I
> >> > understand technically how you did it. I understand your motivation
> >> > doing that but I don't agree this is the right approach (I think it 
> >> > causes
> biases).
> >> > So let me try to understand better:
> >> > On slide 9 of your focus meeting presentation
> >> > https://drupal.star.bnl.gov/STAR/system/files/CME_FOCUS.pdf, you
> >> > state:
> >> > (1) If Delta gamma_bkg. is negative then it is taken as zero.
> >> > (2) If gamma_SS is not negative and gamma_OS is not positive then
> >> > delta gamma = 0.
> >> > Now to slide 25, let's take one centrality say 40-50%, you have the
> >> > blue points (signal) and red+green points (bkg). The 8 points to
> >> > the right of this centrality: all of them have negative bkg and
> >> > negative Delta gamma, so they are not counted in your calculation
> >> > of CME fraction. Now you're left with the two leftmost points. Do
> >> > both points satisfy (2) above? I know both points seem to have
> >> > bkg>0 & Delta
> >> > gamma>0 but it's unclear if they satisfy SS<0 & OS>0. Assume they
> >> > gamma>do,
> >> > then you're taking average of these two data points. For the sake
> >> > of simplicity, let me say you have only one point left. Your f_cme
> >> > is basically the (Delta gamma of those events in that Dbmax bin)
> >> > - (Delta gamma of a random collection of events in the same
> >> > centrality bin which happen to have the same Dbmax_shuffle bin)
> >> > - (Delta gamma of those same random events calculated after the
> >> > charges are shuffled) Do I understand it correctly?
> >> >
> >> > Best regards,
> >> > Fuqiang
> >> >
> >> >
> >> >
> >> >> -----Original Message-----
> >> >> From: jagbir <jagbir AT rcf.rhic.bnl.gov>
> >> >> Sent: Sunday, December 13, 2020 10:12 AM
> >> >> To: Wang, Fuqiang <fqwang AT purdue.edu>
> >> >> Cc: STAR Flow, Chirality and Vorticity PWG
> >> >> <star-fcv-l AT lists.bnl.gov>;
> >> >> star-cme-
> >> >> focusgroup-l AT lists.bnl.gov; aggarwal AT pu.ac.in
> >> >> Subject: Re: [Star-fcv-l] FCV PWG meeting, 18/Nov/2020 (Wed)
> >> >> 9:30am (New York time zone)
> >> >>
> >> >> Dear Fuqiang, all,
> >> >>
> >> >>    Sorry for not answering your email. Infact, I did not look this
> >> >>    email. Please go through my replies below:
> >> >> ------------------------
> >> >>
> >> >>   1. A few events do not satisfy this cut so not including in it
> >> >> Db+-max
> >> >>      but in overall calculations all events are included.
> >> >>
> >> >>   2. Yes
> >> >>
> >> >>   3. We reshuffle charges in each event. We donot randomize charges
> >> >>      according to the positive/negative charge ratio of the given
> >> >> event.
> >> >>      In fact, we pick up one event and reshuffle positive/negative
> >> >> charges
> >> >>      keeping theta,  phi, number of postive charges and number of
> >> >> negative
> >> >>      charges as such. After this we calculate gamma correlator.
> >> >> This procedure
> >> >>      is repeated for each event. The Db+-max of reshuffle  is a
> >> >> bit bit wider
> >> >>      than the  real distribution which may be due to some
> >> >> correlations in the
> >> >>      real data whereas reshuffle is purely randomize. Db+-max
> >> >> binning is
> >> >>      done on the basis of same fractions.
> >> >>
> >> >>   4. Let me explain this point
> >> >>
> >> >>      We pick up a real data event and calculate following
> >> >>      i)  Dbmax+- of real data event
> >> >>      ii) reshuffle charges in an event
> >> >>
> >> >>      iii) again calculate Dbmax+- and termed it Db+-max of charge
> >> >> reshuffle
> >> >>      iv)  calculate gamma of real data event
> >> >>      v)   calculate gamma of reshuffle event
> >> >>
> >> >>      Now for a given centrality
> >> >>      Steps i) to v) repeated for each event. Db+-max (data) and
> >> >> Db+-max(reshuffle)
> >> >>      sliced into ten percentile bins.
> >> >>      Now average gamma is found in every sliced Db+-max (data) and
> >> >> Db+-max(reshuffle)
> >> >>      from the respective event samples. It should be noted that
> >> >> events in the top
> >> >>      say 10% Db+-max(data) are not the same as in the top 10%
> >> >> Db+-max(reshuffle) i.e,
> >> >>      real events in the top 10% Db+-max(data) are different from
> >> >> those top 10%
> >> >>      Db+-max(reshuffle). Now the correlated background is
> >> >> caculated from the real events
> >> >>      corresponding to the top 10% Db+-max(reshuffle) events.
> >> >>
> >> >>       Please clarify the following
> >> >>
> >> >>       Of course you've also removed the large charge-shuffle
> >> >> background which is basically
> >> >>       an autocorrelation effect (sort to speak) due to the Dbmax
> >> >> (and
> >> >> Dbmax_shuffle)
> >> >>       selection bias.
> >> >>
> >> >>   5.  Db+-max distribution is sliced in to ten percentile bins
> >> >> which represent
> >> >>       different amount of charge separation in each sliced db+-max
> >> >> bin.
> >> >> Let us
> >> >>       say we have Db+-max = 2, in this case fractional dumbbell
> >> >> charge separation
> >> >>       f_DbCS = Db+-max-1=1 i.e., 100% back-to-back charge
> >> >> separation i.e.,
> >> >>       positive charged particles on one side of the dumbbell and
> >> >> negative charge
> >> >>       particles on other side of the dumbbell. So, computing gamma
> >> >> in different
> >> >>       Db+-max and calculating things is different from just making
> >> >> a single wide
> >> >>       bin as you mentioned. This method is designed to get
> >> >> CME-like enriched sample
> >> >>       in given collision centrality as one divides all events into
> >> >> different collision
> >> >>       centralities depending on either the impact parameter or
> >> >> event multiplicity but
> >> >>       one does not study all events taken together without making
> >> >> different
> >> >>       collision centrality classes. However, for a single wide
> >> >> Db+-max bin as you
> >> >>       wrote we will get zero signal.
> >> >>
> >> >>       Please explain the following:
> >> >>
> >> >>       So is your finite signal really due to the difference
> >> >> between the average of ratios
> >> >>       and the ratio of averages (or perhaps also due to residual
> >> >> effect from shuffling)?
> >> >>
> >> >>
> >> >> Thank you,
> >> >>
> >> >> with regards,
> >> >> Jagbir Singh
> >> >>
> >> >>
> >> >>
> >> >> On 2020-11-18 23:18, Wang, Fuqiang wrote:
> >> >> > Hi Jagbir,
> >> >> >
> >> >> > Your results are quite interesting. I have a few further
> >> >> > questions about the details of your analysis:
> >> >> > 1. For each event you have Dbmax with the condition of |Dbasy|<0.25.
> >> >> > You bin events of each centrality in Dbmax. You use all events
> >> >> > in your analysis (i.e. you're not throwing away events based on
> >> >> > Dbmax or Dbasy), right?
> >> >> > 2. In your calculation of gamma=<...>/v2c for a particular Dbmax
> >> >> > bin of a given centrality, the v2c is calculated using those
> >> >> > events only, right?
> >> >> > 3. For the charge reshuffle, you reshuffle the charges of all
> >> >> > events, and repeat your analysis from step 1 (i.e. you treat
> >> >> > this as a completely separate "new" data sample), right? Did you
> >> >> > "randomize" the charges according to the positive/negative
> >> >> > charge ratio of the given event? On s11, the Dbmax_shuffle
> >> >> > distribution is a bit wider than the real distribution, do you
> >> >> > understand why? How do you bin the Dbmax and Dbmax_shuffle into
> >> >> > 10 bins, respectively (same bin edges or same fractions)?
> >> >> > 4. Your correlated background gamma is calculated for the Dbmax
> >> >> > bin where Dbmax is from the charge-shuffled events, but using
> >> >> > restored charges, right? If so, then you're effectively taking
> >> >> > gamma difference between Dbmax_i events and Dbmax_shuffle_i
> >> >> > events (which are different events), right? Of course you've
> >> >> > also removed the large charge-shuffle background which is
> >> >> > basically an autocorrelation effect (sort to
> >> >> > speak) due to the Dbmax (and Dbmax_shuffle) selection bias.
> >> >> > 5. You divide Dbmax (and Dbmax_shuffle) into 10 bins and do your
> >> >> > analysis in each bin separately, and then take the weighted
> >> >> > average for your f_cme result. You could just use a single wide
> >> >> > Dbmax (and
> >> >> > Dbmax_shuffle) bin, then in principle you should get zero signal
> >> >> > because the correlated "background" is your real signal since
> >> >> > they are now identical event sample. So is your finite signal
> >> >> > really due to the difference between the average of ratios and
> >> >> > the ratio of averages (or perhaps also due to residual effect from
> shuffling)?
> >> >> >
> >> >> > This is a complicated analysis. It would be really good to have
> >> >> > more discussions so the details can flesh out better.
> >> >> >
> >> >> > Thanks,
> >> >> > Fuqiang
> >> >> >
> >> >> >
> >> >> >
> >> >> >> -----Original Message-----
> >> >> >> From: Star-fcv-l <star-fcv-l-bounces AT lists.bnl.gov> On Behalf
> >> >> >> Of jagbir via Star- fcv-l
> >> >> >> Sent: Tuesday, November 17, 2020 10:49 AM
> >> >> >> To: ShinIchi Esumi <esumi.shinichi.gn AT u.tsukuba.ac.jp>; STAR
> >> >> >> Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>
> >> >> >> Subject: Re: [Star-fcv-l] FCV PWG meeting, 18/Nov/2020 (Wed)
> >> >> >> 9:30am (New York time zone)
> >> >> >>
> >> >> >> Dear ShinIchi, Prithwish and Jiangyong,
> >> >> >>
> >> >> >> I would like to give "Update on event by event charge
> >> >> >> separation in
> >> >> >> Au+Au collisions at 200GeV with STAR detector"
> >> >> >>
> >> >> >> Please add me to agenda.
> >> >> >> I will post my slides later.
> >> >> >>
> >> >> >> Thankyou,
> >> >> >> Jagbir Singh
> >> >> >>
> >> >> >> On 2020-11-16 15:57, ShinIchi Esumi via Star-fcv-l wrote:
> >> >> >> > Dear FCV PWG colleagues
> >> >> >> > We will have our weekly FCV PWG meeting on coming Wednesday
> >> >> >> > 18/Nov/2020
> >> >> >> > 9:30AM (in BNL) at our usual time and place. So if you have
> >> >> >> > anything to present, please let us know and please post your
> >> >> >> > slide by
> >> >> Tuesday.
> >> >> >> > We'll talk about the "HLT express productions" in the
> >> >> >> > beginning of the meeting as you see in the agenda page.
> >> >> >> > Jiangyong, please send a link to your slide from last week.
> >> >> >> >
> >> >> >> > The zoom room link, ID and password are in our usual drupal
> >> >> >> > agenda page below.
> >> >> >> > Please also keep in mind that all the preliminary plots
> >> >> >> > should have already been there in the summary area below.
> >> >> >> > Best regards, Jiangyong, Prithwish and ShinIchi
> >> >> >> >
> >> >> >> > Meeting agenda page with zoom link :
> >> >> >> > https://drupal.star.bnl.gov/STAR/blog/jjiastar/bulkcorr
> >> >> >> >
> >> >> >> > Preliminary page :
> >> >> >> > https://drupal.star.bnl.gov/STAR/pwg/bulk-correlations/bulkco
> >> >> >> > rr-
> >> >> >> > pre
> >> >> >> > lim inary-summary
> >> >> _______________________________________________
> >> >> >> > 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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