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  • From: Nihar Sahoo <nihar AT rcf.rhic.bnl.gov>
  • To: Youqi Song <youqi.song AT yale.edu>
  • Cc: STAR HardProbes PWG <star-hp-l AT lists.bnl.gov>
  • Subject: Re: [Star-hp-l] Paper proposal for collinear jet mass measurement
  • Date: Fri, 10 Mar 2023 22:19:08 +0530

Hi Youqi,

2D plot doesn’t present the results very well as you can see in the projection plot. I would suggest to add these two plots as two panels of Fig2.

would agree that from slide 35, we see that dM=0 jets have on average
a larger angular scale for the first splitting, and vice versa. But
I'm not sure why you think that's related to the zg plot in figure 3.
Are you trying to make a connection to Monika's measurement where we
see that large Rg jets have a more steeply falling zg?

Yes, along the same line. The physics should be the same.
In my perspective, all these results are connected and we are just trying to interpret in different ways.

Cheers
Nihar


On 2023-03-10 22:02, Youqi Song wrote:
Hi Nihar,

We aren't planning to include this projection on slide 35 in figure 2,
since the information is contained in the left hand side 2D plot. I
would agree that from slide 35, we see that dM=0 jets have on average
a larger angular scale for the first splitting, and vice versa. But
I'm not sure why you think that's related to the zg plot in figure 3.
Are you trying to make a connection to Monika's measurement where we
see that large Rg jets have a more steeply falling zg?

Best,
Youqi

On Fri, Mar 10, 2023 at 11:09 AM Nihar Sahoo
<nihar AT rcf.rhic.bnl.gov> wrote:

Hi Youqi,

Thank you for preparing this plot in slide 35.
Do you want to include this figure as one panel of Fig2?

Now if I compare Zg of fig -3 and Rg plot on slide 35, it looks like
no
grooming (dM=0) case jets have wider angle and vice versa. Is that
correct?

I will send email request to Rongrong by tomorrow, I am traveling.

Cheers
Nihar

On 2023-03-10 17:35, Youqi Song wrote:
Hi Nihar,

In case my other email got lost in the thread for this week's PWG
meeting, I would like to point you to slide 35 of


https://drupal.star.bnl.gov/STAR/system/files/prelim_request_030923.pdf.
This might answer your question regarding:

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.

Please let us know when you put in the request for PWGC review to
Rongrong. Thank you!

Best,
Youqi

On Mon, Mar 6, 2023 at 2:34 PM Youqi Song <youqi.song AT yale.edu>
wrote:

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 [1] [1]

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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