STAR HardProbes PWG

[Youqi Song <youqi.song AT yale.edu>]

Hi Nihar,

Thanks for the comments. I have updated my slides here: https://drupal.star.bnl.gov/STAR/system/files/star_collab_meeting_030623.pdf. In addition to Raghav's comments, please find my response below:

Best,

Youqi

Slide 4: 

Where is "PYTHIA6 STAR" on left side "Delta M" plot? And same for Fig.2 right.

We think that a comparison with the PYTHIA8 Detroit tune should be sufficient and better since it is a tune that includes newer RHIC data.

What is "Delta_M" distribution for q vs g jet for this collinear drop jet measurement? Can we say something here on this? It would be an important information. 

Can we add some PYTHIA simulation for the q vs g jet for these plots?

Please see slide 5 in the updated slides for these.

Slide07
"       "Observed an anti-correlation between the amount of early-stage
radiation and the angular scale of a later-stage splitting, where a
large groomed jet radius indicates small or no branching prior to the
SoftDrop splitting "
This statement is not clear what exactly it says.

I think this conclusion is coming from the statement (Slide-5) of "the
dM/M distributions anti-correlated with Rg"
Then it is not clear how do we know these are "early-stage radiation"
and "later-stage splitting".
More explanation or better paraphrase is needed to make it clear.

Raghav answered this in his response to slide 6 question 3: "the early splits are defined via the definition of the formation time in QCD which is inversely prop to angle and energy - taken from the splitting functions." I think the cartoon on slide 16 (of the new version) also helps illustrate this point.

"Agreement/disagreement with MC event generators (pending finalizing
systematic uncertainties)" -> Figures 1,2, and 3 show that MC event
generators are in agreement with the data. Is not that?
Then why "/disagreement"?

We think it's possible that after finalizing the systematics, the error bars in the figures would become smaller and not cover some of the MC curves. In any case, the main physics message of this measurement (correlations between dM vs zg and Rg) is drawn from the data themselves, and wouldn't be affected by the comparison with the MC.

Slide-11

Are we going to include Jet M distribution as one of supplementary
figures?
If yes, then it is not clear why do we need this figure as supplement
material? Particularly "M vs Q".
It sounds like a bit arbitrary.
Could you explain here?

We don't plan to include the jet M distributions in supplementary material. As for whether to include "M vs Q", I will leave that decision to Helen and Raghav.

 

Slide-18,19:

It shows "hadronization" has biggest effect on the collinear drop.
Then how reliable is it to say about early and later splitting as we
mention in Slide 6-7?

Like we have mentioned on slide 19 (slide 20 of the new version), "hadronization smears/shifts the distributions, but the correlation with and without hadronization is the same." For example, in the top left figure of slide 20, when we turn off hadronization, in the dashed curves, dM/M decreases with increasing Rg (as we move from blue to green to orange). This is the same trend as the solid curves with hadronization on. Similarly, for the top right figure, the flattening of zg with increasing dM/M is the same trend between the dashed and solid curves.

 

On Mon, Mar 6, 2023 at 1:17 PM Raghav Kunnawalkam Elayavalli via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hi Nihar, 

Please find a few quick answers from the airport to your questions below. I will respond to the rest later today after i land and get to my destination. 

Cheers
Raghav 


**************************************
First Name - Raghav 
Last Name - Kunnawalkam Elayavalli
email - raghav.ke AT vanderbilt.edu 
website - https://www.raghavke.me 

RHIC/AGS UEC member
Assistant Professor of Physics
Stevenson Center 6410
Physics & Astronomy Department
Vanderbilt University 
Nashville, TN 37235-1807
<they/them>

**************************************

On Mar 2, 2023, at 7:07 AM, Nihar Sahoo via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hello Youqi,

As I mentioned we will discuss with Rongrong to find a nearest date for PWGC review.

In the mean time, Please find my comments below on these nice results.


SLide-4:

What is the extra information we get from the right side plot of obeservable "a"? Is not that the left plot "Delta M" is sufficient to measure Collinear drop observables?

The quick answer for us is that - theorists are able to calculate ‘a’ as opposed to ‘\delta M’ because a is normalized by the jet pT. this makes the calculation in SCET doable and easier on the theoretical uncertainties as they don’t need to vary the energy scale. 

Where is "PYTHIA6 STAR" on left side "Delta M" plot? And same for Fig.2 right.

We can certainly add it to the plots as we have done in the past. Given that we have the pythia 8 detroit tune here, it more or less covers the variation. 

What is "Delta_M" distribution for q vs g jet for this collinear drop jet measurement?
Can we say something here on this? It would be an important information.

from a purely conceptual basis - we know that the jet mass distinguishes q vs g jets, we also know that groomed mass distinguishes q vs g less but we can assume that the discriminative power is probably less. Therefore, delta-m, i would naively assume has a much weaker ability to distinguish between q vs g jets. In our sample of jets, the q vs g fraction steadily increases from about 60-40 for the 20ish GeV jets. so increasing the jet pT does change 

Can we add some PYTHIA simulation for the q vs g jet for these plots?

I think we had truth level quark and gluon jet curves for the m vs charge back during the preliminary discussion. Based on the discussion i mentioned above, we can produce this curve but i hope it doesnt hold up the forward progress on the paper. 

Slide-6:

1. Do you have a plot to show for different "Delta_M/M" what is the distribution of "Rg"?
You could add another panel plot with Fig.3 to show Rg distribution (Similar to Zg distribution).

It is important to show for different "Delta_M/M" regions later splitting dominates by showing Rg distribution in this measurement.

So you want to see the other axis projection on figure 2 then? it is possible sure but isnt the information already available in the dM/M vs Rg? 

2. "Similar trend for higher pT range" ->Where do you get this conclusion? There is only one pT range 20-30 GeV/c is shown. (Same for Slide-5)

we have analyzed the other pT bins and maybe we can show it in the appendix. 

3. "Suggests how the amount of initial wide and soft emission …" ->How do we know these are "wide angle" emission?

this is also an answer for the question below - the early splits are defined via the definition of the formation time in QCD which is inversely prop to angle and energy - taken from the splitting functions. 

Slide07
" "Observed an anti-correlation between the amount of early-stage radiation and the angular scale of a later-stage splitting, where a large groomed jet radius indicates small or no branching prior to the SoftDrop splitting "
This statement is not clear what exactly it says.

I think this conclusion is coming from the statement (Slide-5) of "the dM/M distributions anti-correlated with Rg"
Then it is not clear how do we know these are "early-stage radiation" and "later-stage splitting".
More explanation or better paraphrase is needed to make it clear.


"Agreement/disagreement with MC event generators (pending finalizing systematic uncertainties)" -> Figures 1,2, and 3 show that MC event generators are in agreement with the data. Is not that?
Then why "/disagreement"?

Slide-11

Are we going to include Jet M distribution as one of supplementary figures?
If yes, then it is not clear why do we need this figure as supplement material? Particularly "M vs Q".
It sounds like a bit arbitrary.
Could you explain here?


Slide-18,19:

It shows "hadronization" has biggest effect on the collinear drop.
Then how reliable is it to say about early and later splitting as we mention in Slide 6-7?


Thank you
Nihar

On 2023-03-02 03:19, Nihar Sahoo via Star-hp-l wrote:

Hello Youqi,
Thank you for this paper proposal.
Yes, results and the physics conclusions look good to me.
We can move forward for the PWGC review and we will discuss with
Rongrong to find a date.
Cheers
Nihar
On 2023-03-01 21:40, Youqi Song via Star-hp-l wrote:

Hi conveners,
Here are the slides for the presentation yesterday where we updated
the paper proposal
https://drupal.star.bnl.gov/STAR/system/files/star_collab_meeting_022823_1.pdf.
We think we are ready to move to PWGC review and Barbara is also happy
with us moving forward. Please let us know if you have any questions
or comments. Thank you!
Best,
Youqi, Raghav and Helen
On Thu, Feb 16, 2023 at 1:18 PM Youqi Song <youqi.song AT yale.edu>
wrote:

Hi HP conveners,
I would like to follow up on the paper proposal I presented at our
PWG meeting last week. I have updated my slides here

https://drupal.star.bnl.gov/STAR/system/files/paper_proposal_021023.pdf

based on the feedback I got from the meeting:
Slide 12 - I've made the conclusions in a bullet point form.
Hopefully this highlights our physics messages more crisply.
Slide 17 - I included an example of a large dM jet from a PYTHIA
event.
As mentioned last week, we have been talking to some theorists who
agreed to provide some predictions for the collinear jet mass. I am
also finalizing the systematic uncertainties so that we can arrive
at a more concrete comparison with the MC generators.
We would like to know if this analysis could be pushed to PWGC
review soon or if there is anything else that people would like us
to prepare for. Please let us know if you have any questions or
comments. Thanks!
Best,
Youqi

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