STAR HardProbes PWG

[Barbara Trzeciak <barbara.trzeciak AT gmail.com>]

Hi Rongrong,

nice slides. I have only a minor comment  sign off.

- s19: Indication of a global trend of RAA vs. Npart -  I would add: , for different colliding systems and energies

- Just a question, I guess you're going to explain it verbally, but for my understanding. What do you mean by "How about p+p at RHIC?" on s.17 ?

Cheers,

Barbara

On Mon, Jul 4, 2022 at 2:36 PM Rongrong Ma via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hello Nihar

Thanks for your further comments. I have updated my slides at the same link: https://drupal.star.bnl.gov/STAR/system/files/RMa_2022_RBRC_v2.pdf. 

Slide #8: done

Slide #9: I added "Scattering off medium constituents?". I am not sure about "Large vacuum radiation" since it should be included in the PYTHIA baseline. 

Thanks. 

Best

Rongrong

On Jul 3, 2022, at 10:52 PM, Nihar Sahoo via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hello Rongrong,

Thank you for addressing my comment and answering my questions.
I have remaining comment/suggestion, with this I sign off.

Slide#8: dN/pT (R=0.2) /dN/pT (R=0.5)  ->  dN/dpT (R=0.2) / dN/dpT (R=0.5)

"Effects of wake?" -> Do we need to point to this physics only here?
There are other physics also.

I agree with you, however, I think if you could mention along with this (Effect of wake) other three effects like "Rutherford Scattering off quasi-particle of QGP", "Multiple scattering and medium induced gluon radiation in QGP", and "Large vacuum radiation"; (In my view, one-two of these three effects are more feasible explanation of this observation ;) )
That could give a clear picture of possible effects of this observation.

SLide#10
_ Please mention "Delta R" somewhere
_Do we need to mention here the matching criteria?
Do you mean the Delta R between HardCore and Matched jets? I will
mention orally that they are matched geometrically

That is fine.

I am not sure about this. This is what is stated in the paper "We
observe a clear dijet imbalance indicating jet quenching effects in Au
+ Au collisions for all HardCore jets including the wide angle jets."
Essentially, we are saying that the shapes are different between p+p
and Au+Au for HardCore jets.

That is OK.

We have done a calculation of the total charm production cross
section in Au+Au, which was found to be compatible to p+p. See slide 5
of
https://drupal.star.bnl.gov/STAR/files/QM2022_poster_slides_Vanek_v09.pdf.
So there aren't more charm quarks produced in HI collision, but rather
more charm quarks form Lc and Ds, at least in the kinematic region we
are measuring, and consequently less for D0 and D+/-.

Thank you for this explanation.

Regards
Nihar

On 2022-07-02 20:14, Rongrong Ma wrote:

Hello Nihar
Thanks for your nice comments. A new version has been uploaded to
Drupal.
Please see my replies inline:

On Jul 2, 2022, at 1:17 AM, Nihar Sahoo via Star-hp-l
<star-hp-l AT lists.bnl.gov> wrote:
Hello Rongrong,
Thanks for sharing your nice HP talk.
Please find my comment and question below.
Slide#6: "high-pT leading particle "  -> "high-pT constituent
particle"

I changed to "high-pT leading constituent". I think it is important
to point out that the requirement is only for the leading particle,
otherwise, people might think we make such requirement for all the
constituents.

"single hadrons" -> "inclusive charged hadrons"

Done

Slide#7 "spectrum shape" I understand the reason to mention this
that jet pT spectra shapes are different for pi0 and gamma.
But not sure if it is ok to include this with color
factor and mean path length dependence.
"Spectrum shape" is after hadronization.
You may consider to include another bullet about "Jet
pT spectral shapes are different for pi0+jet and gamma+jet"

I added "Different spectrum shapes" as a sub-bullet now. I agree that
it is not a motivation as other two points, but rather a consequence
we need to deal with.

"Similar suppression for γ-jet and π0-jet" -> "Similar suppression
for γ-jet and π0-jet within uncertainty"

Done

You could also point out  that "for R=0.5, IAA(pt) shape is
different than R=0.2"

Done

SLide#8:
"Ratio of cross sections " -> in this context "Ratio of yield as a
function of jet pT"  (these are semi-inclusive measurement)

Changed to "Ratio of yields"

Slide#9:
Title "Inter-jet Broadening" -> "γ-jet and π0-jet acoplanarity" or
simply "Jet acoplanarity in heavy-ion collisions"

Changed to "Jet acoplanarity"

For this slides, I suggest to include p+p data and Pythia8
comparisons to convince people that both are consistent at 9-11 GeV
ET.
(For note: In case someone ask to have same kinematic comparison for
pp like 11-15 GeV, you could say that we have done that measurement
recently; but not shown here And for pi0+jet they are also
consistent within uncertainty; we are working for publication.)

This is a good point. Replaced the left plot with pp figure.
I moved R = 0.2 results to backup

"Effects of wake?" -> Do we need to point to this physics only here?
There are other physics also.

This is one mechanism which seems to be able to explain both R = 0.2
and R = 0.5. I think it would be interesting to discuss a bit about
this. I put a question mark there to indicate it is not the only
explanation.

SLide#10
_ Please mention "Delta R" somewhere
_Do we need to mention here the matching criteria?

Do you mean the Delta R between HardCore and Matched jets? I will
mention orally that they are matched geometrically

Slide#11
"< AJ > " -> Do you mean average AJ ?

Yes

Another important info from this measurement was "No significant
difference between p+p and Au+Au of jet substructure with hardcore
selection"
Do you want to point this out?

I am not sure about this. This is what is stated in the paper "We
observe a clear dijet imbalance indicating jet quenching effects in Au
+ Au collisions for all HardCore jets including the wide angle jets."
Essentially, we are saying that the shapes are different between p+p
and Au+Au for HardCore jets.

Slide#17
"Redistribution of charm quarks in HI collisions?" Not sure but is
not that "More production charm quarks in HI collisions?"
Trying to understand "Redistribution of charm…"

We have done a calculation of the total charm production cross
section in Au+Au, which was found to be compatible to p+p. See slide 5
of
https://drupal.star.bnl.gov/STAR/files/QM2022_poster_slides_Vanek_v09.pdf.
So there aren't more charm quarks produced in HI collision, but rather
more charm quarks form Lc and Ds, at least in the kinematic region we
are measuring, and consequently less for D0 and D+/-.

Slide#25
"Inter-jet broadening" -> "Jet acoplanarity"

Done

Slide#27:
Just curious: Do you know why we do not have projection of J/psi v1
between pT:9-14 GeV/c  where we have projection for v2 upto pT:14
GeV/c?
Is this just we don't show or any reason?

My guess is that the v1 measurement is much more challenging compared
to v2.

Just a suggestion to include STAR HP kinematic coverage BUR plot for
RUn23+25, good to show at the end.

Done.
Best
Rongrong

Regards
Nihar
On 2022-07-02 01:56, Rongrong Ma via Star-hp-l wrote:
Hello All
This is an invited talk on sPHENIX relevant STAR results and plans
at
the Predictions for sPHENIX RBRC Workshop
(https://www.bnl.gov/sphenix2022/index.php). I focus mainly on jets
and HF results. Please send me your comments. Thanks.
Best
Rongrong
On Jul 1, 2022, at 4:22 PM, webmaster--- via Star-hp-l
<star-hp-l AT lists.bnl.gov> wrote:
Dear Star-hp-l AT lists.bnl.gov members,
Rongrong Ma (marr AT bnl.gov) has submitted a material for a review,
please have
a look:
https://drupal.star.bnl.gov/STAR/node/60153
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