STAR HardProbes PWG

[Helen Caines <helen.caines AT yale.edu>]

Hi,

 Since I brought this up at the meeting, let me chip in where my question came from. The Spin group in the past made a detailed study of the pp (its 2012 data I think) and concluded that the tracking efficiency uncertainty was smaller than we usually quote. They were exploring this, to my memory, to try to beat down the uncertainty on the jet cross-section measurements. 

I’m sure many were involved, but Dmitri Kalinkin sticks in my mind as one of the lead analyzers of this study. Indeed his thesis (

https://drupal.star.bnl.gov/STAR/files/phd-thesis.pdf ) shows  around page 112 that the data-simulation match is very good and the uncertainty therefore less. This is in-line with a previous study that showed that for pp the uncertainty on the tracking efficiency is 3.3% (that was from another Spin/Cold QCD thesis from Texas A&M. These are statements from theses so maybe further studies showed a different final conclusion, but I thought we should check.

For Leszek’s study maybe this difference doesn’t matter, but it seems a shame to artificially inflate the uncertainties on our pp results by assuming uncertainties from Au-Au, which naively one can understand as  possibly being larger

Helen

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On Sep 29, 2023, at 1:05 PM, Sooraj Radhakrishnan via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hi Leszek, Nihar,

   The tracking efficiency task force has studied the efficiencies for 2018 and 2019 Au+Au datasets. Petr can comment more details and if other datasets were looked at. Also, as you can see from the links Nihar shared, for the 2018 case, the evaluations are limited by the smaller r range without the iTPC. For typical cuts used in analyses, the uncertainty is around 5% for the 2018 dataset. So for your case 5% uncertainty on tracking, that we typically use, is still a good choice 

Best,

Sooraj

On Thu, Sep 28, 2023 at 9:47 PM Nihar Sahoo via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hello Leszek,

After going through Petr's presentation slides, the uncertainty on
efficiency was calculated based on AuAu data and that has both DCA and
nhits dependence.
For DCA < 2 cm and nhits >15, that is 5%.
But we need to make sure if this number is true for pp data too.

Some of his presentation are here:
https://drupal.star.bnl.gov/STAR/system/files/TrkEff.pdf
https://drupal.star.bnl.gov/STAR/system/files/2023_PWG.pdf

Let's see if Petr can chime in, otherwise we can contact him offline to
know the details.

I believe this would be a minor correction to your data and that can be
fixed at the GPC level.
If you have paper and AN ready, then we can start looking at these.

I hope this helps you.

Thank you
Nihar



On 2023-09-29 00:39, Leszek Kosarzewski wrote:
> Hello Nihar
>
> Thanks for the feedback, I will update the paper page and finish the
> responses and I hope we can move on quickly with a GPC formation.
> Could you sent a link to that new estimate of the tracking efficiency
> systematic uncertainty in p+p?
>
> Best regards, Leszek
>
> czw., 28 wrz 2023 o 11:05 Nihar Sahoo via Star-hp-l
> <star-hp-l AT lists.bnl.gov> napisał(a):
>
>> Hello HP-pwg,
>>
>> Here is the link to the slides that I discussed.
>> Please note that we have included analyses those are STAR
>> preliminary
>> now.
>> If we have missed any, please inform us.
>>
>> https://drupal.star.bnl.gov/STAR/blog/nihar/HPpwg-analyses-status
>>
>> Thank you
>> Nihar for hp-pwg conveners
>>
>> On 2023-09-25 17:42, Nihar Sahoo via Star-hp-l wrote:
>>> Hello All,
>>>
>>> We will have our HP-pwg meeting this Thursday (28th Sep) at 10 AM
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>>>
>>> NOTICE: PAs are requested to update us their paper proposal plan
>> and
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>>
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>>> Join ZoomGov Meeting
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--

Sooraj Radhakrishnan

Research Scientist,

Department of Physics

Kent State University

Kent, OH 44243

Physicist Postdoctoral Affiliate

Nuclear Science Division
Lawrence Berkeley National Lab
MS70R0319, One Cyclotron Road

Berkeley, CA 94720

Ph: 510-495-2473

Email: skradhakrishnan AT lbl.gov

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