STAR HardProbes PWG

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

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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