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star-fcv-l - Re: [Star-fcv-l] ICPPA proceedings from Egor

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Subject: STAR Flow, Chirality and Vorticity PWG

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  • From: Prithwish Tribedy <ptribedy AT rcf.rhic.bnl.gov>
  • To: egroker <egroker1 AT gmail.com>, "STAR Flow, Chirality and Vorticity PWG" <star-fcv-l AT lists.bnl.gov>
  • Subject: Re: [Star-fcv-l] ICPPA proceedings from Egor
  • Date: Mon, 12 Oct 2020 16:59:57 -0400

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




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