STAR Flow, Chirality and Vorticity PWG

["Tang, Aihong" <aihong AT bnl.gov>]

Hi CW,

The goal is not precise modeling of the background (we will move away from saying background “truth”, that was just convenient). The goal is use the “same” kaon pairs with and without detector effects. The differences in these two (folding and scaling) are due to detector effects/acceptance. We get the former from published phi data and decay them without cuts, and the latter is from real data with all analysis cuts.

Thank you for the quick response. Let me inquire once more, do you possess a derivation supporting the above procedure ? While I understand the necessity for having "same" kaon pairs for the convenience of taking ratios, it's important to note that this does not correctly reflect real-world scenarios.  In reality, kaons can travel in any direction, not just confined to the transverse plane. I reiterate, rotation in the transverse plane artificially distorts rho_00 in a non-straightforward way.    

To use an analogy, it's akin to trying to find a lost key under a lamppost simply because it's convenient, even though the key was likely dropped elsewhere. 

You haven't addressed my second question regarding why the correction involves multiplication (although I suspect it may be correct, I'd appreciate seeing the derivation).

I'm also perplexed by your characterization of the results as consistent between the current and previous ones. The green and cyan bands (numerator and denominator for your ratio) in your previous results largely overlapped, whereas in the new results, they diverge significantly by many sigma away.  I am not convinced that switching between full EP and sub EP can cause a such big difference. 

Thank you,

Aihong

On Apr 19, 2024, at 2:09 PM, Robertson, Charles William <rober558 AT purdue.edu> wrote:

Hello Aihong,

Please find my reply below in blue:

From reviewing your slides (https://drupal.star.bnl.gov/STAR/system/files/SpinAlignmentFCV041724__.pdf), my understanding is that you formed two kaon groups, one simulated from the decay of phi with a characteristic pt and rapidity, and the other consisting of background kaons. For the former group, there is no eta cut, meaning there is no loss due to finite acceptance in eta. However, for the latter, the eta cut is applied as their kinematics are matched to real data (which is with eta cut). Following this, you rotated kaons in both groups in the transverse plane, calculated <cos^2 theta*> for each group, and then took the ratio, claiming it as the correction factor on <cos^2 theta*>, correct ?

The first group is from simulated phi decay with published pt, v2(pt). This data is green and is labeled “data folding” on slide 11. There is no eta cut on these kaons in green. The red data on slide 11 is the data folding with eta cut on kaons.

The second group is from kaons in data, not simulation. These kaons are weighted to have kinematics as same as decay kaons in data, at single particle level. The decay kaon kinematics in data are identified on slides 8-9, the weighting is demonstrated on slide 10.  We then re-run the data with this weighting applied to each kaon in data.

Yes, for both groups one kaon is rotated in the transverse plane and we get <cos^2 theta*> for both and take the ratio or difference.

Your slides provide a clear overview of what you did, but I'm interested in understanding the rational behind each step. A comprehensive derivation would be helpful to clarify this further.  

For instance, could you elaborate on why you believe a rotation in the transverse plane would effectively generate "background truth", especially considering that in a realistic scenario, a daughter particle can move in any direction, not just restricted to the transverse plane ? Why you don't worry that a rotation in the transverse plane is an _artificial_ distortion of rho_00 ?  Additionally, I'd like to understand the reasoning behind your final step of multiplying by the ratio to obtain the correct <cos^2 theta*>. Why is it a simple multiplication by the ratio instead of a simple addition of the difference (you are probably right on this point, but I'd like to see a derivation for it)? 

The goal is not precise modeling of the background (we will move away from saying background “truth”, that was just convenient). The goal is use the “same” kaon pairs with and without detector effects. The differences in these two (folding and scaling) are due to detector effects/acceptance. We get the former from published phi data and decay them without cuts, and the latter is from real data with all analysis cuts.

Having a complete derivation alongside a breakdown of each term or component corresponding to what you measure would greatly assist in our understanding. Even as someone who considers themselves as expert, I'm finding it challenging to follow the progress, so any clarification would be beneficial. If anyone else feels they can understand and explain it more clearly, I'd greatly appreciate their input too.

Lastly, I noticed a significant difference in your correction factor if compared to one of your previous presentations (slide 9 and 10 in the link below)

https://drupal.star.bnl.gov/STAR/system/files/FCV081623_5.pdf

In these slides, your correction factor (green/cyan) differs significantly from what you presented on Wednesday, particularly at larger InvMass (~1.04-1.08). What is the cause of it ?

From my reading of those slides the folded data (green), from simulation, agree reasonably well between both presentations. For the cyan, which is from decay kaons in data, there can be some slight difference due to analysis cut difference since QM. But, there is at least one other difference that I’m aware of. The old presentation used full event Psi2 to identify and scale kaons in data because we were using the full event Psi2 for rho_00. We now use subevent Psi2 in order to compare with Nature.

Thank you,

-CW

---

From: Tang, Aihong <aihong AT bnl.gov>
Sent: Friday, April 19, 2024 11:41 AM
To: STAR Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>
Cc: Robertson, Charles William <rober558 AT purdue.edu>
Subject: Re: [Star-fcv-l] FCV PWG meeting on 17/April/2024 Wed. 9:30 AM EDT

 

---- External Email: Use caution with attachments, links, or sharing data ----

Hi CW,

I wanted to follow up our discussion from Wednesday. 

From reviewing your slides (https://drupal.star.bnl.gov/STAR/system/files/SpinAlignmentFCV041724__.pdf), my understanding is that you formed two kaon groups, one simulated from the decay of phi with a characteristic pt and rapidity, and the other consisting of background kaons. For the former group, there is no eta cut, meaning there is no loss due to finite acceptance in eta. However, for the latter, the eta cut is applied as their kinematics are matched to real data (which is with eta cut). Following this, you rotated kaons in both groups in the transverse plane, calculated <cos^2 theta*> for each group, and then took the ratio, claiming it as the correction factor on <cos^2 theta*>, correct ?

Your slides provide a clear overview of what you did, but I'm interested in understanding the rational behind each step. A comprehensive derivation would be helpful to clarify this further.  

For instance, could you elaborate on why you believe a rotation in the transverse plane would effectively generate "background truth", especially considering that in a realistic scenario, a daughter particle can move in any direction, not just restricted to the transverse plane ? Why you don't worry that a rotation in the transverse plane is an _artificial_ distortion of rho_00 ?  Additionally, I'd like to understand the reasoning behind your final step of multiplying by the ratio to obtain the correct <cos^2 theta*>. Why is it a simple multiplication by the ratio instead of a simple addition of the difference (you are probably right on this point, but I'd like to see a derivation for it)? 

Having a complete derivation alongside a breakdown of each term or component corresponding to what you measure would greatly assist in our understanding. Even as someone who considers themselves as expert, I'm finding it challenging to follow the progress, so any clarification would be beneficial. If anyone else feels they can understand and explain it more clearly, I'd greatly appreciate their input too.

Lastly, I noticed a significant difference in your correction factor if compared to one of your previous presentations (slide 9 and 10 in the link below)

https://drupal.star.bnl.gov/STAR/system/files/FCV081623_5.pdf

In these slides, your correction factor (green/cyan) differs significantly from what you presented on Wednesday, particularly at larger InvMass (~1.04-1.08). What is the cause of it ?

Thank you.

Aihong

On Apr 17, 2024, at 9:25 AM, Robertson, Charles William via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:

Hello Convenors,

My slides for today can be found here:

https://drupal.star.bnl.gov/STAR/system/files/SpinAlignmentFCV041724__.pdf

Thanks,

-CW

---

From: Star-fcv-l <star-fcv-l-bounces AT lists.bnl.gov> on behalf of Cameron Racz via Star-fcv-l <star-fcv-l AT lists.bnl.gov>
Sent: Tuesday, April 16, 2024 10:16 PM
To: STAR Flow, Chirality and Vorticity PWG <star-fcv-l AT lists.bnl.gov>
Cc: Cameron Racz <cracz001 AT ucr.edu>
Subject: Re: [Star-fcv-l] FCV PWG meeting on 17/April/2024 Wed. 9:30 AM EDT

 

---- External Email: Use caution with attachments, links, or sharing data ----


Hello Conveners,

My slides for the meeting can be found at this link

https://nam04.safelinks.protection.outlook.com/?url="https%3A%2F%2Fdrupal.star.bnl.gov%2FSTAR%2Fblog%2Fcracz%2FProton-Purity-Results-FXT-Energies-Part-3&data=05%7C02%7Crober558%40purdue.edu%7Cef41a2124ea045bd955808dc5e84815d%7C4130bd397c53419cb1e58758d6d63f21%7C0%7C0%7C638489170418467690%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=8%2FFP%2Fodot1s3wZfRhik8lKpsqTg00O5bKJ8u8YgaAts%3D&reserved=0

Cameron Racz
Ph.D. Candidate
Heavy-ion Physics Group
University of California, Riverside






> On Apr 15, 2024, at 10:20 PM, Cameron Racz <cracz001 AT ucr.edu> wrote:
>
> Hello conveners,
>
> I would like to give another update on "Proton purity for v3 at FXT energies – Part 3”. I will send out the link to slides later.
>
> Thank you,
>
> Cameron Racz
> Ph.D. Candidate
> Heavy-ion Physics Group
> University of California, Riverside
>
>
>
>
>
>
>> On Apr 14, 2024, at 11:00 PM, subhash via Star-fcv-l <star-fcv-l AT lists.bnl.gov> wrote:
>>
>> Dear All,
>>
>> We shall have our weekly FCV PWG meeting this Wednesday (17/Apr/2024) at 9:30 AM EDT. If you wish to present please let us know. The agenda will be collected at: https://nam04.safelinks.protection.outlook.com/?url="https%3A%2F%2Fdrupal.star.bnl.gov%2FSTAR%2Fblog%2Fjjiastar%2Fbulkcorr&data=05%7C02%7Crober558%40purdue.edu%7Cef41a2124ea045bd955808dc5e84815d%7C4130bd397c53419cb1e58758d6d63f21%7C0%7C0%7C638489170418474260%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C0%7C%7C%7C&sdata=SCSx6%2FGL2ExLmn1jsq%2FB1h3Ll8BRs%2BPFjd4pWnIpxn4%3D&reserved=0
>> Please send us your slides by Tuesday. Zoom details are copied below.
>>
>>
>> Please take a note of the STAR internal deadlines for CPOD and SQM. Presenters are requested to give regular updates in the PWG.
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>> Prithwish, Zhenyu and Subhash
>>
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