STAR HardProbes PWG

[Nihar Sahoo <nihar AT rcf.rhic.bnl.gov>]

Dear Peter,

Thank you for bringing this topic.
I agree that this is a new direction of work to extract the medium 
properties by comparing the data with theoretical model calculations 
using Bayesian Inference.
ANd agree that this is a synergy between theory and experimentalists, 
and this direction of work should be discussed.

we certainly need to include this in the white paper at least one para.

Do you think it is Ok if we could discuss and mention this in the 
section of the STAR's future measurements and extraction of the QGP's 
transport properties? Or do you think we can include that discussion in 
the STAR highlight section?
Any suggestion in this direction would be helpful.

If you agree, could you please provide one paragraph on it?

Please have a look at the updated version here: 
https://drupal.star.bnl.gov/STAR/system/files/STAR_Hot_QCD_White_Paper_Sep12.pdf

Thank you
Nihar for the conveners


On 2022-09-12 00:36, Peter Jacobs wrote:
> Hi everyone,
>
> I would like to reiterate my proposal that the White Paper and
> recommendations make explicit mention of the growing role that
> Bayesian Inference is playing in our field. In my view this approach
> is essential for heavy-ion physics going forward, to enable us to
> fully understand the complex multi-messenger data we have recorded and
> are rapidly generating (much) more of. Simple 1-d comparison to a
> bunch of model curves ("this one is good, this one not so much,
> recoils-off doesn't work, etc.") is interesting up to a point, but
> very limited in scope. I therefore advocate adding a brief paragraph
> on this topic.
>
> Also, Recommendation 3 says "Continued strong funding of the RHIC Hot
> and Cold QCD theoretical groups and collaborations..." However,
> JETSCAPE, Trajectum, etc are not theory collaborations, nor are they
> experimental collaborations - they are a third kind of "Computational"
> collaboration in our field. I advocate some change of wording to
> reflect that.
>
> Note that this concept - that a new kind of "Computational NP" is
> emerging based on Bayesian Inference and ML approaches - got good
> traction at the Computational NP pre-Town Hall meeting last week at
> SURA headquarters, and this point will be reflected in the
> recommendations that that group will present to each of the topical
> Town Meetings. Similarly, there is ongoing discussion within the HEP
> Snowmass process of the emergence of a new subfield of "Computation
> HEP" that is neither experiment nor theory but an amalgam, utilizing
> ML, Bayesian Inference, and related tools.
>
> It is I think important for the Agencies to hear this message from
> multiple directions, including consumers of this development (i.e.
> experimental collaborations) and not just its primary advocates.
>
> Regards,
>
> Peter
>
> On Sun, Sep 11, 2022 at 11:44 AM Raghav Kunnawalkam Elayavalli via
> Star-hp-l <star-hp-l AT lists.bnl.gov> wrote:
>
> > Dear Nihar, Barbara, Yi, Sooraj, all
> >
> > Apologies for the delay from my side. I have a few comments on the
> > current writeup of our hot qcd white paper on the jet section and
> > the few sentences in promised related to the time/temperature
> > dependence. Based on the discussion during last week’s meeting, I
> > also discuss a few words on a general paragraph related to jets that
> > we can present as a bigger picture. Your thoughts and comments are
> > most welcome.
> >
> > Line numbers are based on the pdf attached below.
> > L 62 - instead of ’shorter and shorter length scales’ ->
> > ‘varying scales, from the macroscopic to microscopic lengths’
> > L 63 - the QGP’s transport properties
> > L 63-66- you mention the usefulness of jets and then in the next
> > sentence describe what they are… so maybe reverse this order?
> > L 66 - loses a fraction of its energy
> > L 69-71- this sentence seems a bit redundant here, especially when
> > considering the next sentence.
> > L 75 - jet quenching -> jet-medium interactions (of which quenching
> > is a part)
> > L 76 and later on - I think we should fold in our studies on pp
> > substructure as a necessary prerequisite towards quantitative
> > studies of the QGP evolution in both its perturbative description
> > and hadronization (which is still unknown). The way its currently
> > written seems a bit like its something else that we do on the side
> > with the connection unclear.
> > It would be good to emphasize here that one of the next steps in
> > studying the QGP is to quantify its properties during its evolution.
> > And one way in which we can do that is to use jets via their
> > multi-scale evolution from pQCD to npQCD and hadronization. This
> > provides a natural timescale that one can exploit in heavy ion
> > collisions to then extract a temperature dependence of the transport
> > parameters such as \hat{q}. This is the reason why we want to
> > quantify jet topologies and that requires us to understand the
> > substructure and clustering tree in pp collisions. So I would
> > rephrase the sentence in L 76 with something along the lines of what
> > i mentioned above and head into the next paragraphs.
> > L 99 - I understand the point here but i would probably rephrase
> > this as a feature than a bug (which is how its written with the
> > emphasis on a measurement ‘bias’). Different jets lose energy
> > differently and potentially same jets lose energy differently
> > (depending on the strength of fluctuations vs path length for
> > example). Such a system essentially forces us to make all possible
> > types of measurements at varying kinematics and selections so that
> > one can put the pieces of the puzzle together.
> > L 101 - this paragraph seems overly technical, especially with the
> > comparison of pp data to pythia which doesnt really add much to the
> > discussion here.
> > L 113 - This can just be on jet substructure or something like
> > jet-qgp space-time evolution where the pp is not only a reference,
> > but a necessary step to comprehend before we move to heavy ions. We
> > have measured the evolution of jet substructure along its shower and
> > found deviations from perturbative description of the splitting
> > kinematics for later emissions/splits. This points to significant
> > non-perturbative contribution to the description of jet substructure
> > along the jet where at a particular formation time which can be
> > experimentally measured.
> > So this is where we can bring back a bigger picture to summarize -
> > From our measurements, we have two sets of studies which are
> > complementary to each other with the scattering tomography and the
> > space-time evolution picture. Both of which are necessary and have
> > extensions to heavy flavor, such as heavy flavor jets and
> > resonances, and other aspects we are yet to study about the medium
> > such as hadron production affected by jet quenching etc.
> >
> > Cheers
> > Raghav
> >
> > **************************************
> > First Name - Raghav
> > Last Name - Kunnawalkam Elayavalli
> > email - raghav.ke AT vanderbilt.edu
> > website - https://www.raghavke.me [2]
> >
> > RHIC/AGS UEC member
> > Assistant Professor of Physics
> > Stevenson Center 6410
> > Physics & Astronomy Department
> > Vanderbilt University
> > Nashville, TN 37235-1807
> > <he/them>
> > **************************************
> >
> > > On Sep 5, 2022, at 6:43 AM, Nihar Sahoo via Star-hp-l
> > > <star-hp-l AT lists.bnl.gov> wrote:
> > >
> > > Hello All,
> > >
> > > We will have our regular HP-pwg meeting this Thursday (Sep 8th) at
> > > 10 AM BNL time. Let us know if you want to present and update your
> > > analysis.
> > >
> > > As you may know from the minutes of last week pwgc meeting
> > > (Rongrong's email), currently conveners from all pwg are preparing
> > > a first draft of STAR Hot QCD white paper which should be ready by
> > > Sep 7-9; then that will be sent to the collaboration for comments
> > > during the weekend before the collaboration meeting. And the final
> > > white papers is aimed to be ready by Sep. 21st. It is very tight
> > > schedule.
> > >
> > > Hence, this week we will discuss on the STAR Hot QCD white paper
> > > and also STAR contribution for next LRP. So please try to join
> > > this week to discuss more on this topic and it would be helpful
> > > for us to get your inputs. If you are interested in to contribute,
> > > please let us know.
> > >
> > > HP working group weekly meeting info:
> https://drupal.star.bnl.gov/STAR/pwg/Hard-Probes/Weekly-HP-PWG-meeting
> > > Join ZoomGov Meeting
> https://bnl.zoomgov.com/j/1611419615?pwd=VW1hNm43ZDd5d2EvK2R4aEJsQ2ZNZz09
> > > [1]
> > >
> > > Meeting ID: 161 141 9615
> > > Passcode: 744968
> > >
> > > Regards,
> > > Barbara, Yi, Sooraj, and Nihar
> > > _______________________________________________
> > > Star-hp-l mailing list
> > > Star-hp-l AT lists.bnl.gov
> > > https://lists.bnl.gov/mailman/listinfo/star-hp-l
> >
> > _______________________________________________
> > Star-hp-l mailing list
> > Star-hp-l AT lists.bnl.gov
> > https://lists.bnl.gov/mailman/listinfo/star-hp-l
>
> --
> Peter Jacobs
> pmjacobs AT lbl.gov
>
> Nuclear Science Division,
> Lawrence Berkeley National Laboratory,
> 1 Cyclotron Road,
> Berkeley, California,
> U.S.A. 94720
> Tel. (510)486-5413
> Cell: (510) 688-0055
>
>
>
> Links:
> ------
> [1] 
> https://urldefense.com/v3/__https://bnl.zoomgov.com/j/1611419615?pwd=VW1hNm43ZDd5d2EvK2R4aEJsQ2ZNZz09__;!!P4SdNyxKAPE!H-t6abboxeouQc5VWJiyh0r7W5HMUtUGBDNK_iG-oic5FAsOfkrX2sGnEM5MLIlRpcbyHNa-dxQoZzEye1n9EBtDAxVoIVFaZQ$
> [2] 
> https://urldefense.com/v3/__https://www.raghavke.me__;!!P4SdNyxKAPE!H-t6abboxeouQc5VWJiyh0r7W5HMUtUGBDNK_iG-oic5FAsOfkrX2sGnEM5MLIlRpcbyHNa-dxQoZzEye1n9EBtDAxX-GJuWNg$