STAR Flow, Chirality and Vorticity PWG

[egroker <egroker1 AT gmail.com>]

Dear Conveners,

If you don't have more comments, I'd like to ask you for approval of my proceeding to the next step.

Thank you,
Egor Alpatov

On Tue, Oct 13, 2020 at 1:19 AM egroker <egroker1 AT gmail.com> wrote:

Hello Prithwish,
Thank you for your comments, I implemented them in my proceeding, please have a look: 
https://drupal.star.bnl.gov/STAR/system/files/ICPPA_Proceeding_Alpatov_V4.pdf

About some global changes:

>line 74: This line starting with “Global polarization” is not clear What is used as a part of systematics? Just two ways of hyperon reconstruction (traditional vs KF particle) or/and variation other cuts— it’s not clear, be specific.

I moved systematics description to the Results section.

Thank you,
Egor Alpatov

On Tue, Oct 13, 2020 at 12:00 AM Prithwish Tribedy <ptribedy AT rcf.rhic.bnl.gov> wrote:

Hello Egor,
Please consider my comments on your nice proceedings :
https://drupal.star.bnl.gov/STAR/system/files/ICPPA_Proceeding_Alpatov_V3.pdf

With these include I sign off.

At many places, I suggest you either use: "Polarization", "Ionization"
and "Behavior" or use "Polarisation", "Ionisation" and "Behaviour"
consistently.

Abstract line 6:
nuclear-nuclear
—>
nucleus-nucleus

Abstract line 7:
Spin-orbit coupling alignes
—>
Spin-orbit coupling aligns

Abstract line 8:
directions of produced particles with system angular momentum, known as
vorticity
—>
directions of produced particles with system angular momentum, through
the creation of local vorticity

line 18:
quark-gluon plasma
—>
the quark-gluon plasma

line 19:
since their creation
—>
since their early days of operation

line 19:
Collective behaviour
—>
The collective behavior of QGP

line 20:
to speculation
—>
to the possible conclusion

line 21:
main part of these
—>
main features of these

line 22 (optional change):
however, directed azimuthal
—>
however, observations such as directed azimuthal


line 22:
anizotropic flow
—>
anisotropic flow

It is not clear how the current second para in the introduction is
relevant to your proceedings and measurement of global polarization. Why
bring the context of “directed flow” here ? Is there a connection — you
need to be specific. Therefore, I suggest the following change:

line 23:
for flow understanding could be the initial conditions
—>
to understand directed flow measurements could be an improved knowledge
of initial conditions — particularly along the longitudinal or rapidity
direction.

After line 24 you need to add a sentence, something like “Measurements
such as global polarization of hyperon can lead to better understanding
of both the fluid properties of the medium and the longitudinal
structure of the initial state”.

line 25:
The studies of non-central collisions suggested to evidences of QGP
vortical structure
—>
Model studies of non-central collisions suggested evidences for vortical
structure in the QGP.

line 26-27:
As a result, globally polarized  particles were observed in the STAR
experiment [6].
—>
This provides a possible explanation of the globally polarized particles
that were observed by the STAR experiment [6].

line 36:
While most of theoretical calculations
—>
While most of the theoretical calculations

line 42:
  at sNN = 27 GeV
—>
at √sNN = 27 GeV

line 54:
plane angle calculations.
—>
plane angle calculations, as proxies for the reaction plane angle.


line 56:
“should be” —> “can be”,
“first-order event plane, Ψ1” —> “the true first-order event plane, Ψ1”

line 57: Here, please provide the acceptance of EPD (2.1<η<5.1) and BBC
(3.3<|η|<5.1).

line 62:
“a measured event plane”
—>
“the measured event plane”

line 63:
EPD resolution is about 1.5 times larger than that for BBC
—>
EPD resolution is about 1.5 times larger than that for BBC due to wider
acceptance and better granularity

line 68:
tracks lay
—>
tracks to lie

line 69:
were reconstructed via it’s decay to
—>
candidates were reconstructed via their decays to


line 74: This line starting with “Global polarization” is not clear What
is used as a part of systematics? Just two ways of hyperon
reconstruction (traditional vs KF particle) or/and variation other cuts
— it’s not clear, be specific.

line 76:
“spectator nucleus”
—>
“spectator nucleons”

line 78:
“with taking into account”
—>
“after incorporating the”

line 79:
“could is estimated”
—>
“could be estimated”

line 80: You have already introduced α_H in line 30. Also, you’ve
introduced Ψ^obs and Res(Ψ1) before in section 2.1. Edit this sentence
accordingly.


line 84: Before this line add “Two methods that were used to measure the
Ξ polarization are as follows.”


line 88:
daughters pair
—>
daughter’s pair

line 90:
is the background fraction at the invariant mass, M_inv
—>
is the invariant mass distribution of the background fraction


line 94:
the mean sine of the
—>
the mean sine-component of the

line 94:
assumed to be zero due the high purity of the hyperons and, 95 hence,
neglected.
—>
assumed to be zero due the high purity of the hyperons sample.

line 98:
“of Λ with Ξ polarization”
—>
“of Λ with the new measurements of Ξ polarization”

line 100:
“and presented at Quark Matter 2019 results”
—>
“and the preliminary results presented at the Quark Matter 2019
conference”

line 102:
“was measured”
—>
“was measured as a part of this study”

line 102-103:
“polarization in the dependence on the collision centrality”
—>
“polarization as a function of collision centrality”

line 103:
“in comparison with Λ polarization”
—>
“with the same for Λ polarization”

Fig.5:
“via Λ daughter”
—>
“(via Λ daughter)”

Line 108: Both the methods are done via Λ daughters, so to clarify I
suggest we write:
“via Λ daughters”
—>
“via transfer to decay daughters”

Line 109:
“Weak centrality”
—>
“A weak centrality”

line 111: I am not sure what to say here. “Within 2σ” of what ?

line 113:
“consistent with P_Λ trend”
—>
“consistent with that of Λ hyperon measurements”



Best,
Prithwish







On 2020-10-12 14:43, egroker via Star-fcv-l wrote:
> Dear Conveners,
>
> Thank you for your feedback
> I implemented comments from Jiangyong, please have a look at new
> version:
> https://drupal.star.bnl.gov/STAR/system/files/ICPPA_Proceeding_Alpatov_V3.pdf
>
> I guess, in future I'll try to use EP method as main option for
> KFParticle calculations, and I'll be back to PWG with KFParticle with
> helices comparison ASAP.
>
> Thank you,
> Egor Alpatov
>
> On Mon, Oct 12, 2020 at 7:10 PM ShinIchi Esumi
> <esumi.shinichi.gn AT u.tsukuba.ac.jp> wrote:
>
>> Dear Egor
>> Your comment about the following is indeed interesting and it might
>> mean the
>> invariant mass method is not really adequate for the KF particle
>> method, since
>> the relative BG contribution is not really determined by the
>> “random” combinatorial
>> contribution. This is also seen just by looking at the Minv
>> distribution, which does
>> not look like the single gaussian from the detector resolution +
>> random combinatorial
>> BG, which should have a smooth function with Minv, which is most
>> likely not the
>> case and might even have a weak peak at the lambda mass, because of
>> the way
>> how it is done in KF. I hope you will come back to the PWG with more
>> detailed
>> studies on these points. Thank you very much.
>> Best regards, ShinIchi
>>
>> “When we were doing this for the traditional helix method, we had
>> a big background
>> with some proton-pions pairs with random proton's phi, BUT in
>> KFParticle these particles
>> are also fitted into the decay point, which, as we see from the fact
>> that their invariant mass
>> doesn't correspond with Lambda, doesn't even exist. While for
>> particles of interest in mass
>> window (Lambda and Xi) we probably get something like "true" angle
>> between particles from
>> these fit, it also creates "false" angles for tracks in the
>> background. This leads to the possibility
>> of some "big background polarization", which doesn't really exist.
>> So for now my opinion is
>> that we SHOULD assume background polarization to zero, because these
>> are our expectations
>> from physics."
>>
>>> On Oct 12, 2020, at 1:50, egroker <egroker1 AT gmail.com> wrote:
>>>
>>> Dear Conveners,
>>>
>>> I've already written about implementation of Shinichi's comments,
>> but I guess it could be lost in this dialogue.
>>> Please have a look at my proceeding and comment it if necessary:
>>
> https://drupal.star.bnl.gov/STAR/system/files/ICPPA_Proceeding_Alpatov_V2_0.pdf
>>>
>>> Thank you,
>>> Egor Alpatov
>>>
>>> On Thu, Oct 8, 2020 at 11:30 AM egroker <egroker1 AT gmail.com>
>> wrote:
>>> Dear Shinichi,
>>>
>>> Thank you for comments, I implemented almost all of them. Here is
>> the link:
>>>
>>
> https://drupal.star.bnl.gov/STAR/system/files/ICPPA_Proceeding_Alpatov_V2_0.pdf
>>>
>>> And some comments and answers:
>>>
>>>> L20-23 connection from flow to vorticity
>>> I just realised, that in text I didn't mention vorticity yet, and
>> talking about global polarization bit later, so i removed it from
>> here. Now the logic is "flow understanding->initial
>> conditions->global polarization, dependent on these conditions too"
>>> Hope it fits well....
>>>
>>>> L57 optical fibers in BBC
>>> From documentations we have much more optical fibers in EPD, but
>> they also are used in BBC
>>>
>>>> Fig.3 Fit of <sin> vs Minv: background polarization
>>> The effect from making parameter free is ~ 2% both for Lambdas and
>> Xi, but I didn't include it yet in systematics. I'll try to say why.
>>> When we were doing this for the traditional helix method, we had a
>> big background with some proton-pions pairs with random proton's
>> phi,
>>> BUT in KFParticle these particles are also fitted into the decay
>> point, which, as we see from the fact that their invariant mass
>> doesn't correspond with Lambda, doesn't even exist.
>>> While for particles of interest in mass window (Lambda and Xi) we
>> probably get something like "true" angle between particles from
>> these fit, it also creates "false" angles for tracks in the
>> background.
>>> This leads to the possibility of some "big background
>> polarization", which doesn't really exist
>>> So for now my opinion is that we SHOULD assume background
>> polarization to zero, because these are our expectations from
>> physics.
>>> I could make picture wider, so there'll be more observable big
>> fluctuations around zero for Lambdas, but I'm afraid in this case
>> this picture will become just a mess, cause I need to keep the same
>> y-axis range for Xi and Lambda <sin>.
>>>
>>> Anyway, I remember my promise to show differences between
>> KFParticle and Helices methods, and I will do it ASAP and look at
>> this point more precisely.
>>>
>>> Thanks,
>>> Egor Alpatov
>>>
>>> On Thu, Oct 8, 2020 at 6:31 AM ShinIchi Esumi via Star-fcv-l
>> <star-fcv-l AT lists.bnl.gov> wrote:
>>> Dear Egor and all
>>> I send you my comments on your nice proceeding, which would need
>> to be submitted almost
>>> simultaneously just after your talk during the conference, this is
>> almost impossible for us to
>>> review both your talk and proceedings at the same time, it is not
>> your fault though… I would
>>> sign off with the following comments implemented.
>>> Best regards, ShinIchi
>>>
>>> L11-12: It would be better to say why this is important.
>>> L20-23: It would be better to have some connection from flow to
>> vorticity like directed flow and global polarization etc, between
>> the two sentences.
>>> L25-26: You are missing a word after polarized or remove "by
>> this..."
>>> L37: ... differential measurements like pT, rapidity and azimuthal
>> dependences etc?
>>> L38: , and this could be achieved by additional measurements using
>> ...
>>> L57: I thought optical fibers are used only for EPD, not for BBC,
>> maybe I’m wrong, please make sure.
>>> Eq.4: I know people uses tan^-1, but I would choose to write
>> atan2(Qy, Qx)...
>>> L66: TPC B-field (parallel to Z) would limit the pT, not the total
>> momemtum...
>>> L67: The number of hits per track automatically limits the eta
>> acceptance, but you can do the additional cut on eta, so you can
>> select eta, so it sounds odd to say "should".
>>> L89-90 and Eq.6 : superscript is changing "Bg" and "bckg", I would
>> prefer just "bg". "sgn" can be spelled out as "signal".
>>> Fig.3: Are there better choice of figures? The BG region could
>> have even a larger polarization than the signal region especially
>> for Lambda, so the zero polarization assumption would not hold here.
>> I hope your systematic error would include at least free constant
>> parameter fit for the BG polarization, right?
>>> L102 and 107: A weak centrality dependence could possibly be seen,
>> "observed" might even be too strong, or?
>>> L103: would require
>>> L109: Non-zero sigal with ~2sigma ...
>>>
>>>> On Oct 7, 2020, at 21:28, Takafumi Niida <niida AT bnl.gov> wrote:
>>>>
>>>> Dear Jiangyong and all,
>>>>
>>>> Now this proceedings is under FCV PWG review.
>>>>
>>
> https://drupal.star.bnl.gov/STAR/presentations/icppa-2020/global-hyperon-polarization-auau-collisions-√snn-27-gev-star-experiment
>>>>
>>>> I checked the conference page and it seems they request to
>> submit proceedings just after the conference (by October 11):
>>>>
>>
> https://urldefense.com/v3/__https://indico.particle.mephi.ru/event/35/page/46-conference-proceedings__;!!P4SdNyxKAPE!S09R-z82LnJa6M8RC0xP_jWUpFOKPaFoFtFDx9H02oegCbnRY9y3eWiRTqsZQLP8edefjrzZ$
>>
>>>>
>>>> Best regards,
>>>> Takafumi
>>>>
>>>>
>>>>> On Oct 7, 2020, at 9:07 PM, Jiangyong Jia
>> <jiangyong.jia AT stonybrook.edu> wrote:
>>>>>
>>>>> I confused this as a talk and pressed button by accident, and I
>> did not
>>>>> understand why they need to post proceedings now.
>>>>>
>>>>> Can we restart the process?
>>>>>
>>>>> Jiangyong
>>>>>
>>>>> On 10/7/20 4:31 AM, Takafumi Niida wrote:
>>>>>> Dear FCV and CF conveners,
>>>>>>
>>>>>> I notice that participants for ICPPA (Egor, Eugenia, Petr)
>> posted their proceedings while we went through the talk slides
>> (except Petr). One of them (Egor’s one in FCV) came to star-talks
>> but I didn’t see you made any comment on it. Just in case you
>> overlooked or mixed with the talk slides, I just wanted to ask you
>> to take a look and make comments. It’s also possible that I missed
>> the discussion. If so could you send me the link to the email
>> thread?
>>>>>>
>>>>>> Egor’s proceedings:
>>>>>>
>>
> https://drupal.star.bnl.gov/STAR/presentations/icppa-2020/global-hyperon-polarization-auau-collisions-√snn-27-gev-star-experiment
>>>>>>
>>>>>> Eugenia’s proceedings:
>>>>>>
>>
> https://drupal.star.bnl.gov/STAR/presentations/icppa-2020/pion-femtoscopy-pau-and-dau-collisions-sqrtsnn-200-gev-star-experiment-1
>>>>>>
>>>>>> Petr’s proceedings: Not yet posted
>>>>>>
>>>>>> Thank you.
>>>>>>
>>>>>> Best regards,
>>>>>> Takafumi
>>>>>>
>>>>>
>>>>
>>>
>>> _______________________________________________
>>> 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