STAR HardProbes PWG

[Sooraj Radhakrishnan <skradhakrishnan AT lbl.gov>]

Hi Rongrong,

   Thanks for preparing this nice presentation. I only have a few comments/questions

S6: Is that a conclusion drawn in the paper on different pT dependence? The error bars are large

S7: Might be useful to define I_AA here

S9: of acoplanarity distributions for .... in Au+Au collisions 

S16: regenerated J/Psi v2 seems rather abrupt here and is also not the major takeaway from the measurement

S18: What is the tagging you refer to here? Selecting on smaller R_AA? Or the HFT capability is mentioned?

S18: I would swap the order for S17 and S18

S19: Could add some physics motivation or conclusion on this slide

S22: Can constrain

S28: Wouldnt sPHENIX be able to do the measurement? Is the claim of first needed?

S29: Are these plots with the (to be) published results now?

S30: New channels? what do you refer to here?

S33: I wouldnt say no sign of broadening here, There is deviation from the PYTHIA case

thanks

Sooraj 

On Mon, Jul 4, 2022 at 8:28 PM Nihar Sahoo via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hello Rongrong,

Thank you.

> 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.

That’s fine.
But “vacuum radiation “ I mean here is that Contribution from NLO effect
which is not present in PYTHIA.
Although vacuum (sudakov) radiation is relatively less at RHIC than LHC.

Regards
Nihar

Sent from iPhone



On 2022-07-04 18:05, Rongrong Ma 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
>>> ---
>>> If you have any problems with the review process, please contact
>>> webmaster AT www.star.bnl.gov
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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