STAR HardProbes PWG

[Yi Yang <yiyang0429 AT gmail.com>]

Hi Barbara,

Thanks a lot for the updated version and adding J/psi with jet activity in the slides.

I don't have any further comments.

Cheers,

Yi

On Tue, Aug 23, 2022 at 8:15 PM Barbara Trzeciak <barbara.trzeciak AT gmail.com> wrote:

Hi Sooraj, Yi,

thanks for the comments.

I've uploaded a new version of the slides:

https://drupal.star.bnl.gov/STAR/system/files/STARHFOverview_BTrzeciak_v3.pdf

And please see my replies below.

Yi

  - I think J/psi with jet activity is also the new preliminary from STAR, and it is the first result of this. Do you think that you will have space for this? 

Yes, I fully agree that's a new and important result. Initially I planned to also include the p+p new results, but then I noticed I have only 15+5 so I decided to focus more on heavy ions. 

Nevertheless, I added a slide on the J/psi with jet activity before the outlook. In case I don't have much time at the end, I will go quickly via it. 

Sooraj 

S16: small charm quark flow can be contested here, as we do observe large v2 for D0 mesons (in Au+Au at comparable N_part)

I agree that small regeneration is more probable giving the D0 v2 results. However, D0 v2 comes from both light and charm quarks, and we don't  yet know the precise degree of the charm quark thermalization. I think that with the current J/psi v2 uncertainties we might be consistent with a regeneration in case charm is not fully thermalized and has small flow - it would of course be better to have some models for this. 

This is also a conclusion that we've been making in other talks, so I think it's better to be consistent.

 

S17: Not just in peripheral collisions now from the lower right figure

 For Npart ~> 150 the RHIC and LHC Upsilon(2S) results look consistent. Hint of less suppression for Upsilon(2S) in peripheral collisions is a conclusion that we make in the paper. 

 

Cheers,

Barbara

On Mon, Aug 22, 2022 at 6:56 PM Yi Yang via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hi Barbara,

Thanks a lot for the nice slides, I only have a few comments for your consideration. 

  - p9: loose --> lose

  - I think J/psi with jet activity is also the new preliminary from STAR, and it is the first result of this. Do you think that you will have space for this? 

  

Cheers,

Yi

On Mon, Aug 22, 2022 at 11:59 PM Sooraj Radhakrishnan via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hi Barbara,

   Thanks for preparing these very nice slides. I dont have many comments. I sign off with the few comments below

S7: compared to

S16: small charm quark flow can be contested here, as we do observe large v2 for D0 mesons (in Au+Au at comparable N_part)

S17: Not just in peripheral collisions now from the lower right figure

S19: Since you show the Lc and Ds results it would be good to also have a bullet on coalescence hadronization

thanks

Sooraj 

On Fri, Aug 19, 2022 at 5:12 PM Nihar Sahoo via Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:

Hello Barbara,

Thank you for addressing my comment and answering my questions.
I don't have any further comment. I sign off.

Cheers
Nihar


On 2022-08-19 14:06, Barbara Trzeciak wrote:
> Hi Nihar,
>
> thanks for the comments. I've uploaded a new version:
> https://drupal.star.bnl.gov/STAR/system/files/STARHFOverview_BTrzeciak_v2.pdf
>
> Please see my replies inline below.
>
>> Slide-2:
>> _Initial hard scattering, m_Q >> L_QCD -> I think this should be
>> "Initial hard scattering,  Q >> Λ_QCD" (here Q is momentum
>> transfer; Δt
>> << 1 fm)
>
> Here the argument is about heavy quarks' masses - since the mass is
> larger than the typical non-perturbative QCD scale, the quark quark
> production cross section is calculable with pQCD.
> I modified this bullet a bit.
>
>> _"negligible thermal production, mQ >> T_QGP" -> is not that heavy
>> quark
>> mass m_Q >> T_QGP? I think there is no thermal production of
>> heavy-quark. Am I correct?
>
> There can still be some thermal production, from processes like
> gg->ccbar in the QGP.
> This should depend on the initial temperature and for RHIC, where
> temp. is of the order of 350-400 MeV, it's expected to be negligibly
> small - PHYSICAL REVIEW C 77, 024901 (2008).
>
>> Slide-6
>> Can you please point out if there is any relation between D^0 RAA
>> and
>> D^(+/-)/D^{0} yield ratio?
>> Is there any physics link between Strong suppression of D^0 RAA and
>> D^(+/-)/D^{0} Au+Au same with Pythia8?
>> (Just for my understanding as you put these two figures on one
>> slide)
>
> Here indeed it might not be so obvious. I've put back the plot with
> both D0 and D+ Raa.
> It should be more clear now.
>
>> SLide-8
>> What are these "*" and " ** " in the uncertainty?  [Please mention
>> it]
>
> Explained, thanks for catching it.
>
>> Slide-13:
>> "…unity → suppression…".  I would remove "arrow" and replace
>> "and";
>> (It reads like RpA unity  indicate RAA Strong suppression in AA; I
>> this
>> these are two separate physics: cold vs hot QCD)
>
> Here the point is that the suppression in AA can be not only due to
> the hot nuclear matter effects, but also cold nuclear matter effects
> can play a role.
> In order to quantify the CNM we measured R_pAu, since at high pT it's
> consistent with 1 we can conclude that the suppression seen in AA is
> due to the QGP related effects.
> So I wouldn't say there are two separate physics, CNM effects are
> present in AA collisions as well.
>
>>> Slide-16:
>>> "small regeneration or/and small charm quark flow."
>>> For my understanding,   "small regeneration creates zero v2" Or "
>>> Zero
>>> v2 hence small regeneration" ?
>>> I think latter is true. Right?
>
> Yes, zero v2 points to a sall regeneration effect (in case charm
> quarks flow) or charm quarks' flow is small.
>
>> Outlook:
>> I would suggest to include BUR HF kinematic coverage plot for
>> different
>> observables.
>>
> https://drupal.star.bnl.gov/STAR/system/files/OnlyHPProjectionBUR.pdf
>
> The kinematic coverage is nice, but I think that it doesn't show the
> physics performance as good as the statistical project plots.
> So I would prefer to  leave the plots that I have now and since I have
> only 15+5min (not 20+5 as initially suggested by the organizers) I
> have to skip many things in the presentation.
> I will keep it in the backup.
>
> Cheers,
> Barbara
>
> On Fri, Aug 19, 2022 at 8:12 AM Nihar Sahoo via Star-hp-l
> <star-hp-l AT lists.bnl.gov> wrote:
>
>> A small correction on Slide16 comment:
>>
>> Slide-16:
>> "small regeneration or/and small charm quark flow."
>> For my understanding,   "small regeneration creates zero v2" Or "
>> Zero
>> v2 hence small regeneration" ?
>> I think latter is true. Right?
>>
>> Regards
>> Nihar
>>
>> On 2022-08-19 11:40, Nihar Sahoo wrote:
>>> Hello Barbara,
>>>
>>> Please find my comments and questions below on your nice
>> presentation.
>>>
>>>
>>> Slide-2:
>>> _Initial hard scattering, m_Q >> L_QCD -> I think this should be
>>> "Initial hard scattering,  Q >> Λ_QCD" (here Q is momentum
>> transfer;
>>> Δt << 1 fm)
>>> _"negligible thermal production, mQ >> T_QGP" -> is not that heavy
>>> quark mass m_Q >> T_QGP? I think there is no thermal production of
>>> heavy-quark. Am I correct?
>>>
>>> Slide-6
>>> Can you please point out if there is any relation between D^0 RAA
>> and
>>> D^(+/-)/D^{0} yield ratio?
>>> Is there any physics link between Strong suppression of D^0 RAA
>> and
>>> D^(+/-)/D^{0} Au+Au same with Pythia8?
>>> (Just for my understanding as you put these two figures on one
>> slide)
>>>
>>> SLide-8
>>> What are these "*" and " ** " in the uncertainty?  [Please mention
>> it]
>>>
>>> Slide-13:
>>> "…unity → suppression…".  I would remove "arrow" and replace
>> "and";
>>> (It reads like RpA unity  indicate RAA Strong suppression in AA; I
>>> this these are two separate physics: cold vs hot QCD)
>>>
>>> Slide-16:
>>> "small regeneration or/and small charm quark flow."
>>> For my understanding,   "small regeneration" due to zero v2 Or "
>> Zero
>>> v2 hence small regeneration" ?
>>> I think latter is true. Right?
>>>
>>> Outlook:
>>> I would suggest to include BUR HF kinematic coverage plot for
>>> different observables.
>>>
>>
> https://drupal.star.bnl.gov/STAR/system/files/OnlyHPProjectionBUR.pdf
>>>
>>>
>>> Regards
>>> Nihar
>>>
>>> On 2022-08-18 15:29, webmaster--- via Star-hp-l wrote:
>>>> Dear Star-hp-l AT lists.bnl.gov members,
>>>>
>>>> Barbara Trzeciak (barbara.trzeciak AT gmail.com) has submitted a
>> material
>>>> for a
>>>> review, please have a look:
>>>> https://drupal.star.bnl.gov/STAR/node/60559
>>>>
>>>> Deadline: 2022-08-30
>>>> ---
>>>> 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

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