STAR HardProbes PWG

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

Hello Helen,

Thank you for your email.
I agree with you and your suggestions.

As you mentioned, we need to be a bit careful on overstating and 
interpreting the physics conclusion at this stage.

Regards
Nihar


On 2022-10-10 19:00, Helen Caines via Star-hp-l wrote:
> Hi Nihar, All,
>
> We have all agreed that we should not be presenting results that pop
> up a few days before a conference, but from memory Tristan has been
> presenting to HP regularly that he sees a jet v2 in the Isobar data
> since back in August, not a week ago. So I believe he has been a good
> citizen and is following STAR’s procedures as best he can.
>
> Are the results ready for publication?, No, I believe we are all in
> agreement there. However, I at least have developed some faith in
> where the central values sit based on the cross-checks many of us have
> asked him to perform in the past month or so.
>
> We also want to be cautious about over interpreting, but I think there
> is a middle ground if Tristan uses very careful language. I would
> suggest something like
>
> “ Finite jet v2 combined with observed high pT charged particle RAA
> (Ref Tong) are consistent with naive expectations of path length
> dependent energy loss
>  [Sub bullet] - Need full systematics before drawing strong
> conclusions
>  [Sub bullet]  What if any role does surface biasing from HC jets
> play?
>  [Sub bullet]  What if any role do fluctuations of the medium play?
> “
>
> Maybe there are other cautions and/or possible interpretations we need
> to add? measurements of single particle v2 is finite at high pT?
>
> This allows Tristan to bounce some tentative interpretations off of
> the audience at the workshop - one of the key reasons to my mind of
> presenting preliminary results outside of STAR - while also being
> clear that they  aren’t definitive yet and we might back away from
> them if the uncertainties explode or discussions with the community
> trigger other more likely interpretations.
>
> Helen
>
> ***********************
> Yale University
> Physics Dept. - Wright Lab.
> PO Box 208120
> New Haven, CT 06520
> 203-432-5831
> ***********************
> she/her/hers
> "Life is not about waiting for the storms to pass.
> It's about learning how to dance in the rain." - Vivian Greene
>
> > On Oct 10, 2022, at 2:05 AM, Nihar Sahoo via Star-hp-l
> > <star-hp-l AT lists.bnl.gov> wrote:
> >
> > Hi Rosi,
> >
> > Please find my reply inline.
> >
> > On 2022-10-10 00:29, Rosi Reed wrote:
> > Hi Nihar,
> > A few comments-
> > My overall suggestion on Tristan's presentation is that due to
> > limited
> > time, let's only focus on the observation from this preliminary
> > results.
> > I agree that the time is limited so further analysis is not
> > possible,
> > but I would disagree that it is too limited to think about the
> > interpretation of the result.  I would even venture to say that most
> > of our thinking as a collaboration for what the results mean happen
> > in
> > the week or two before a conference presentation because this is
> > when
> > results are nailed down and people realize they need to say
> > something
> > about them.
>
> We don't have enough supporting results/study to draw any physics
> conclusion from these uncorrected preliminary results. These results
> were presented just 7-8 days before the conference and even we have
> not finished all systematic uncertainties and we did not have enough
> time to discuss and ask for further checks on it. I think we should
> not be hurry to make any physics conclusion keeping Hard probes2023 in
> mind.
>
> > > Sorry, I still don't understand your argument here.
> > > We don't have very good information about jet RAA/RCP in "isobar"
> > > collision mainly kinematic range in pT etc. I know we have BES RCP
> > which
> >
> > > is in Au+Au collision.
> > > Here the system size is smaller compared to Au+AU.
> > > Unless we measure Jet RAA/RCP in Isobar we should not make any
> > > conclusion/statement based on what we know from Au+Au measurement.
> > Actually - Tong is presenting the high pT hadron RAA in the isobars
> > at
> > this very conference, which extends into the pT range of the jets.
> > So
> > we know that the RAA will be ~0.6-0.7 for the kinematic range that
> > Tristan is reporting.  An RAA of less than 1 indicates quenching,
> > and
> > if there is quenching there must be a surface bias.  So I don't
> > think
> > it's fair to say that we don't have good information about the jet
> > RAA
> > as high pT hadrons have always been considered a good proxy for
> > jets.
>
> Tong's RAA results is upto pT 10 GeV/c. But here we are discussing
> about hard-core jet v2 (R=0.2) above jet pT > 10 GeV/c. Hence need to
> be careful.
>
> > Yes, Isobars are smaller than Au+Au, but there is actually a fair
> > amount of data on even smaller systems out there.  For example, we
> > know that the RAA < 1 for Cu+Cu published by STAR in
> > https://arxiv.org/pdf/0911.3130.pdf [2].  There are a number of
> > results out of PHENIX as well.  Just as Zr/Rb is ~1/2 of Au, Cu is
> > ~1/2 of Zr/Rb.
> > I think that it is well established that there is quenching in these
> > smaller systems - what we're working out now is quantifying the
> > details.
> >
> > > We can't say anything more on "jet modification is path-length
> > > dependent" in Isobar collisions; simply because in this
> > > measurement
> > we
> >
> > > have not done any jet modification study.
> > The jet v2 IS a jet modification study. If jets were not modified,
> > the
> > v2 would be nearly zero.
> >
> > > For that we need to explicitly perform jet suppression study for
> > > this
> >
> > > system.
> > With Tong's charged hadron RAA, I think this has been explicitly
> > measured.  However, I would push back here - the very first jet
> > quenching measurements were done long before we measured high pT
> > RAA.
> > This is one analysis, and while I would agree that it is useful for
> > a
> > full understanding of jet quenching in a given system, it's
> > certainly
> > not required.  For that matter, we only published our first jet RAA
> > paper last year.....
>
> We need a detail study on jet RAA/RCP in Isobar collisions for good
> undersanding.
>
> > > A further study is warranted to comment on path-length dependent
> > > jet
> >
> > > modification which we can discuss after HQ.
> > I completely disagree.  We can make a statement that we see
> > path-length dependent modification based on this single measurement.
> > We can't say whether it is dominated by radiative or collisional
> > energy loss, whether MPI effects are larger than LPM effects, what
> > the
> > surface bias is, etc. There's a lot we can't say - but this
> > statement
> > is an incredibly low bar in terms of interpreting the data.
> >
> > > As I mentioned above, we have not done any Aj measurement in this
> > small
> >
> > > system Isobar collisions.
> > > And we do not have enough time to have this discussion before HQ
> > which
> >
> > > we can discuss after the conf.
> > > Using same process/cuts may not imply the jets we find are also
> > surfaced
> >
> > > biased in small system, for this concern we can discuss in details
> > > later.
> > I agree we have not done AJ measurements.  I disagree that the AJ
> > measurement is necessary to state anything about surface bias. AJ as
> > an observable was only invented in 2010 after the start of the LHC
> > runs simply because there was not sufficient theory to compare the
> > new
> > LHC HI jet results to.  The discussions over the surface bias of
> > hard
> > probes date from at least the early 90s.  So we're simply stating a
> > fact, especially in light of Tong's results, that quenching causes a
> > surface bias.  Precisely how much it is, how it compares to Au+Au,
> > and
> > so forth, we don't comment on and can not at this time.
>
> Unless we have Aj measurement in Isobar collision, I will not say
> anything on it.
> Aj in Au+Au we know, but we don't know what will be the result in
> Isobar (relatively smaller system).
>
> > Now, I completely agree that the selections from Au+Au may not map
> > directly onto the Isobars - there is a lot of post-HQ work to do
> > here.
> > We should repeat Nick's very nice differential checks with the v2.
> > I
> > think we can also at least for internal consumption create a raw Aj
> > measurement to compare to Kolja/Nick's results that can allow us to
> > make additional comments.
> > I really don't think we're pushing the boundaries on what can be
> > said
> > here with this measurement, these are incredibly safe statements.
>
> You might be right, but we should do the measurement and show the
> results first in order to make any statement.
>
> Thank you
> Nihar
>
> > Regards,
> > Rosi
> > On Sun, Oct 9, 2022 at 12:02 PM Nihar Sahoo <nihar AT rcf.rhic.bnl.gov>
> > wrote:
> > Hello Rosi,
> > Thank you for your reply.
> > My overall suggestion on Tristan's presentation is that due to
> > limited
> > time, let's only focus on the observation from this preliminary
> > results.
> > for Any physics conclusion we need time to understand and discuss
> > for
> > that we don't have time now.
> > Please find my response inline.
> > On 2022-10-09 20:09, Rosi Reed wrote:
> > Hi Nihar,
> > Just a few comments here:
> > 1. You don't need to put description of "ALCIE sys bands like
> > correlated
> > and uncorrelated etc" One green circle is enough to represent
>  ALICE
>
> > > results.
> > I think it's better to keep their descriptions here - otherwise it
>  is
>
> > STAR telling ALICE what their data should look like.  The
>  correlated
>
> > vs uncorrelated is important for making a statement about the
> > comparison, if everything was uncorrelated the significance of the
> > apparent agreement is much stronger, so I would be worried that by
> > changing their results we would be misleading our audience a
>  little on
>
> > this very interesting result.
>  That is fine and it is just PAs choice.
>
> > > Can you please elaborate how we draw the conclusion of " jet
> > > modification is path-length dependent" in Isobar ?
> > > We don't have any hard-core jet RAA/RCP measurement in isobar. Do
>  we
>
> > > have?
> > We don't have RAA/RCP, but I don't see why this is necessary for
>  the
>
> > statement, we know that jet RAA will < 1 in the isobar system due
>  to
>
> > other measurements made by STAR (and PHENIX).  You could have a
> > path-length dependent modification that averages out to precisely
>  RAA
>
> > = 1, though that would be unlikely in a collision with a center of
> > mass energy greater than ~40 GeV judging by the RCP measurement
>  made
>
> > by Stephen from the BES data.  With a signal at 3.5 sigma, we can
> > state that there is evidence for non-zero jet v2 at RHIC.  There
>  must
>
> > be some geometrical physics process causing this - if there was
>  not,
>
> > then the v2 would be close to zero.  In the paradigm of heavy ion
> > collisions we have a choice of initial state effects (so some
>  MPI),
>
> > pressure gradients and path-length dependent suppression (i.e LPM
> > effect).  We know we can exclude the middle term due to the high
>  Q^2
>
> > and the QGP formation time.  There is no evidence for the former
>  term
>
> > as of yet, so within the paradigm of jets in heavy ion collisions
>  the
>
> > latter is the assumption for the interpretation of the data that
> > remains.  I certainly don't think we can overturn a decades long
> > paradigm on the basis of a single statistics hungry measurement.
>  Sorry, I still don't understand your argument here.
> We don't have very good information about jet RAA/RCP in "isobar"
> collision mainly kinematic range in pT etc. I know we have BES RCP
> which
> is in Au+Au collision.
> Here the system size is smaller compared to Au+AU.
> Unless we measure Jet RAA/RCP in Isobar we should not make any
> conclusion/statement based on what we know from Au+Au measurement.
> But it is fine for me with the statement "there is evidence for
> non-zero
> jet v2 at RHIC in Isobar collision."
> We can't say anything more on "jet modification is path-length
> dependent" in Isobar collisions; simply because in this measurement
> we
> have not done any jet modification study.
> For that we need to explicitly perform jet suppression study for
> this
> system.
> So I suggest to remove "Suggests that jet modification is
> path-length
> dependent, even in medium sized systems!" on slide#18.
> and replacing  this "there is evidence for non-zero jet v2 at RHIC
> in
> Isobar collision." is very important conclusion here which is
> apparent
> from the figure.
> A further study is warranted to comment on path-length dependent jet
> modification which we can discuss after HQ.
>
> > > I would be careful on this statement, as I mentioned we have not
> > done
> >
> > > any dijet Aj study in Isobar to support of the surfaced bias jet
> > > selection. It could be correct but we have not done any
>  measurement
>
> > so
> >
> > > we should abstain mentioning this.
> > I don't believe that we have to measure AJ to state this basic
>  fact of
>
> > nuclear physics.  The surface bias of selecting hard fragmentation
>  has
>
> > been discussed since the earliest papers on jet quenching
>  
> (https://physics.fjfi.cvut.cz/files/predmety/02RQGP/zs1617/GyulassyPluemer.pdf
>
> > [1]
> >
> > > [1] for example), and has been mentioned many times by STAR itself
> > in
> >
> > > a variety of high pt and jet based measurements.  In fact, not
> > > mentioning it after STAR spent so much time discussing jet
> > geometry
> >
> > > evolution in the earlier AJ measurements would actually be akin to
> > > walking back our earlier statements since we're using the same
> > process
> >
> > > in this measurement.
> > As I mentioned above, we have not done any Aj measurement in this
> > small
> > system Isobar collisions.
> > And we do not have enough time to have this discussion before HQ
> > which
> > we can discuss after the conf.
> > Using same process/cuts may not imply the jets we find are also
> > surfaced
> > biased in small system, for this concern we can discuss in details
> > later.
> >
> > > I have also made some comments on Tristan's talk that he'll follow
> > up
> >
> > > on, and the official practice of his talk before the council
> > member
> >
> > > will happen on Monday so there will be a little bit of tweaking,
> > even
> >
> > > after he submits a draft v5.  One quick point on the
> > uncertainties,
> >
> > > Rongrong was quite correct in the meeting on Thursday that the
> > > uncertainty on the tracking efficiency only plays a role in the
> > > uncertainty if we're unfolding.  So there are no further effects
> > that
> >
> > > will change the systematics for this non-unfolded measurement -
> > rather
> >
> > > we're waiting on this as a last cross-check.
> > Looking forward to seeing Tristan's updated version.
> > Cheers
> > Nihar
> > Cheers,
> > Rosi
> > On Sun, Oct 9, 2022 at 4:14 AM Nihar Sahoo via Star-hp-l
> > <star-hp-l AT lists.bnl.gov> wrote:
> > Hello Tristan,
> > Thank you for implementing my comments and your reply.
> > Please find my further comments and reply to your response.
> > All my comments on your recent version (v4).
> > Please don't remove your old version; that can be done after
> > finishing
> > our discussion otherwise it is difficult to follow the slide
>  numbers
>
> > > with new version.
> > > 1) Have you updated your remaining sys uncertainty that we were
> > > waiting
> > > for?
> > > 2)Comments on Figures:
> > > Slide18 fig:
> > > 1. You don't need to put description of "ALCIE sys bands like
> > > correlated
> > > and uncorrelated etc" One green circle is enough to represent
>  ALICE
>
> > > results.
> > > 2. Please include instead STAR sys box's description  in legend
> > > Slide17 fig:
> > > _ Can you include v2 value (with uncertainty) in this figure that
> > > you
> > > get from the fitting?
> > > 3) Additional comment:
> > > I think EPD is used for the first time in jet v2 measurement.
> > > It would be good to include EP resolution plot that you get from
> > > this
> > > measurement.
> > > For that you can combine slide15-16 to make a story for EPD and
>  EP
>
> > > calculation.
> > > 4) Slide18(in vesrion4):
> > > "Suggests that jet modification is path-length dependent, even in
> > > medium
> > > sized systems!"
> > > Can you please elaborate how we draw the conclusion of " jet
> > > modification is path-length dependent" in Isobar ?
> > > We don't have any hard-core jet RAA/RCP measurement in isobar. Do
>  we
>
> > > have?
> > > We can only say so far (from this preliminary study) what you
>  have
>
> > > mentioned in conclusion slide19 (with slight modification
>  "hint…")
>
> > > "Hint of non-zero v2^ch jet is observed in a medium sized system
>  "
>
> > > Please bring this statement in slide18
> > > 5) Slide19(v4 version)
> > > _"A very different system!" -> "A very different kinematic range
>  and
>
> > > system size"
> > > _"v2ch jet is observed despite the introduced surface bias" ->
>  "v2ch
>
> > > jet
> > > is observed despite the possible surface bias"
> > > I would be careful on this statement, as I mentioned we have not
> > > done
> > > any dijet Aj study in Isobar to support of the surfaced bias jet
> > > selection. It could be correct but we have not done any
>  measurement
>
> > > so
> > > we should abstain mentioning this.
> > > If you want, then need to do Aj measurement for this hard core
>  jet
>
> > > selection in Isobar.
> > > _"Our picture of jet quenching is not complete - there is still
>  much
>
> > to
> > discover"
> > Sounds a vague statement. Please mention 1) what is not
> > completed
> > relating to jet quenching? 2) what do you think that needs to be
> > discovered?  Please elaborate this.
> > Remaining reply can be found inline.
> > On 2022-10-09 07:56, Tristan Protzman via Star-hp-l wrote:
> > Hello Nihar,
> > A new draft has been uploaded to Drupal.
> > Note: it should be written as $p$+$p$ and $p$+Au, etc, which is
> > different from the guidance.
> > Fixed.
> > Slide:2
> > _Second bullet seems out of context here. Coupling is large at
>  low
>
> > Q^2
> > then why  is it relevant for the QGP and your jet anisotropy
> > measurements? This part is not clear here.
> > It motivates the need for a perturbative object like jets to
>  probe
>
> > what we actually want to study, the QGP.  Changed text to
>  clarify.
>
> > > Still it is not clear and confusing for 1st and 3rd bullets.
> > > If you want to motivate jet (which pQCD calculable) and this is
>  used
>
> > > to
> > > probe QGP (which is asymptotic region of coupling); then what is
>  the
>
> > > point to mention "alpha_s ~ O(1) at low Q^2."
> > > I would suggest to rephrase;
> > > "Since running coupling is asymptotically small at high Q^2,
>  pQCD
>
> > calculable probes are used to study the QGP medium"
> > Then you don't need 3rd bullet.
> > _ Give reference to the running coupling plot. And you could
> > replace
> > with most updated version where LHC measurements (very highQ2
> > region)
> > are included if you want to start with it.
> > Changed.
> > __GIve a reference or credit for left cartoon._
> > Figure removed, I felt it did not add to the message.
> > Slide:4
> > _3rd bullet: "Leads to path length…"  this is not the only
> > effect;
> > it
> > could be various other contributions like color factor, Temp of
> > QGP,
> > initial gluon density, etc. But you need to mention Your
> > motivation is
> > to study "path length dependence".
> > __ same comment for 4th bullet_
> > I have adjusted this section to clarify that the aspect of jet
> > modification I am trying to study is the path length dependent
> > nature
> > of jet energy loss
> > Slide4 (current  v4)
> > _ "We are interested in understanding the path-length dependence
>  of
>
> > > these processes" -> "We are interested in understanding the
> > > path-length
> > > dependence of jet quenching"
> > > _"Both collisional and radiative" -> "Both collisional and
>  radiative
>
> > energy loss" or "Parton energy loss via both collisional and
> > radiative
> > processes"
> > _ 5th Bullet ("Both collisional and radiative") you need to
> > provide
> > reference to the theory calculation for this L/L^2 dependence.
> > These
> > are
> > model calculations.
> > Slide4 (current v4)
> > _"Both collisional and radiative" -> "Both collisional and
>  radiative
>
> > energy loss" or "Parton energy loss via both collisional and
> > radiative
> > processes"
> > Removed L/L^2 statements as I am not comparing to any models in
> > this
> > presentation
> > _ This slide only focus on jet and jet quenching, but it doesn't
> > motivate your measurement like why jet anisotropy measurement is
> > required? Need to include some text on it.
> > I suggest you need to motivate jet anisotropy before you go to
>  any
>
> > jet
> > analysis details like in Slide5  underlying event discussion
> > The way I have structured my talk is to first motivate that we
> > have
> > observed jet quenching.  I am using the dijet analysis to this
> > end.  I
> > then want to contrast that with azimuthal anisotropy, which is
>  not
>
> > a
> > dissimilar measurement in that it probes jet modification, but
>  it
>
> > does
> > so in a new way.  Therefore, I think it makes sense to talk
>  about
>
> > jet
> > measurements and then the dijet measurement before introducing
>  the
>
> > idea of anisotropy and motivating how that can get us towards
>  the
>
> > missing path length dependence of a dijet analysis.
> > SLide:5
> > _Not clear, what is that right side plot? Is this data or MC
> > simulation.
> > What is pT, of track or jet? What is Delta phi?
> > I agree, this plot was not particularly clear.  I have removed
>  it.
>
> > __"Soft processes produce a fluctuating background" what is
>  that_
>
> > _background? Is it track or _combinatoric_ jet background?_
> > I'm not quite sure I understand what you are asking, it is the
> > tracks
> > from soft processes which produce the combinatorial jet
> > background, so
> > I suppose both?
> > Then it would good to mention, "Soft processes produce a
>  fluctuating
>
> > > uncorrelated background for jet measurement in heavy-ion
>  collisions"
>
> > > Here "uncorrelated" is important.
> > > Slide5 (current v4), right figure is from STAR data or any model?
>  No
>
> > description mentioned there.
> > __3rd _bulltet_ (Estimated…) it should _be sub-bullet_ of 2nd
> > bullet
> > (Soft_
> > _process…)_
> > Changed.
> > __ what is kT?_
> > The k_T jet finding algorithm, clarified.
> > __ Jet area -> Jet area(A)_
> > Changed.
> > Slide6:
> > _Not clear, what is that right side plot? Is this data or MC
> > simulation?
> > What is pT, eta, and phi?
> > This is the total track momentum for eta/phi bins for a
>  collision.
>
> > __"A jet finder… had scattering and other processes" ->" had
> > scattering_
> > _and combinatorial background in heavy-ion collisions"_
> > _2nd bullet is not required if you mention above.
> > _ _I have merged this with slide 5 and changed this wording
> > SLide:7
> > I would suggest to use jet pT as $p_{\rm T, jet}$ throughout
>  your
>
> > presentation.
> > Changed.
> > __Used in other STAR analysis -> Proved references_
> > __Provide _referecen_ to ALICE measurement_
> > Done.
> > Slide:8
> > _Move this slide or Isobar jet pT distribution after your
>  slide14
>
> > where
> > you discuss about Isobar dataset. It seems the left side plot
>  just
>
> > pop-up. This plot should be part of you results discussion even
>  if
>
> > it
> > is
> > a STAR performance plot.
> > Figure removed
> > __"Statistically unlikely for soft processes…" Please rephrase
> > this… not_
> > _clear._
> > Changed to clarify that it is unlikely for soft processes to
> > produce
> > high pt hadrons which look like jets
> > __"May bias jet selection towards surface" Not sure the
>  motivation
>
> > of_
> > _this bullet. _why it is_ important? You are not doing jet
>  RAA/RCP
>
> > study_
> > _and you do not study trigger jet v2 then why it is important if
> > this
> > jet_
> > _is trigger biased or not. These jets should be treated as
> > inclusive
> > _jet_._
> > Is it not important to understand the biases we introduce into
>  our
>
> > measurements?  By requiring the high pT hadrons the selected
>  jets
>
> > are
> > biased towards the surface of the QGP.  This is the motivation
>  for
>
> > one
> > of the items we would like to explore next in this analysis, the
> > variation of the hard core threshold.
> > Slide:9
> > This slide is not relevant. You could put in Backup. (A
> > distraction)
> > I disagree, the story I am hoping to tell with this talk is that
> > we
> > saw signs of jet quenching with measurements like dijet
>  imbalance,
>
> > but
> > that it doesn't tell the complete story.  We can continue our
> > understanding of jet quenching from dijet measurements to jet v2
> > measurements.
> > slide8(in v4)
> > _ we are doing inclusive hard-core jet v2 measurement here. Is
>  not
>
> > > it?
> > > _I am not convinced to motivate with dijet measurement here. Are
>  we
>
> > > going to do any dijet measurement in isobar?
> > > _Selecting a hard-core jet may not imply you select surface
>  biased
>
> > jet.
> > For that you need to show the same dijet Aj measurement in isobar
> > like
> > in Au+Au. If you have any result to demonstrate that you are
> > selecting
> > surfaced bias jet in Isobar, please show those results.
> > I think we have not done that study.
> > Slide:10
> > _ 1st bullet: Why it is important for Dijet imbalance discussion
> > here?
> > You are doing inclusive jet v_n measurement. Not clear to me.
> > See above.
> > Please see above my concerns.
> > SLide12
> > _"A jet in plane interacts with less medium than one out of
>  plane"
>
> > ->
> > "A
> > jet interacts less with medium in plan than out of plane"
> > Changed.
> > __"Since jet production is isotropic, differences in yields are
>  a
>
> > result_
> > _of medium interactions" Not sure, _what you_ want to say here?
> > Please_
> > reprhase_._
> > Changed.
> > __" like flow" Remove this._
> > I included this to help give context for the measurement to an
> > audience who may be familiar with flow studies, but not jet
> > anisotropy
> > studies.  If you feel this is misleading I will remove it.
> > __ you do not discuss what is v_{2}^{jet} is?_
> > Changed equation to remove \Delta\phi -> \Psi_2 - \Phi_jet
> > __"Not a flow effect though!" Can you elaborate this?_
> > I am stating that although it may be described using the same
> > framework as flow measurements, jet v2 is a different process.
> > I would suggest to give a clear idea what could be that different
> > process, For example...?
> > Otherwise do not create unnecessary doubt or make statement just
>  for
>
> > a
> > buzz?
> > SLide13
> > _RHIC produces a different, cooler QGP -> "RHIC produces a
>  cooler
>
> > QGP
> > medium than the LHC"
> > Changed.
> > __"Down to 10 _GeV"_ -> But you are not going to show down to 10
> > GeV.
> > So_
> > _just remove this extra quantifier _subbullet. Main bullet is
> > fine.
> > I do show down to 10 Gev though, my first point is 10-12.5 GeV/c
> > jets.
> > Slide15:
> > - Jet trigger -> You don't use any jet trigger and BEMC info in
> > your
> > measurement. If yes, just remove.
> > I do use the barrel high tower trigger in my analysis, as
>  detailed
>
> > in
> > the preliminary figure request.  I have clarified this as high
> > tower
> > trigger rather than jet trigger.
> > _- Right side STAR detector, please indicate where is TPC, BEMC,
> > EPD_
> > _- Mention kinematic acceptance of these detectors_
> > See updated slides, Yi mentioned this as well
> > Slide16:
> > _you did not discuss what is Delta_phi?
> > I did not, but I am not sure I need to on this slide.  I will
> > discuss
> > it on the next slide.
> > __right side plot, _make title_/_lable_ of x-, y-axis bigger so
> > that
> > it will_
> > _be visible. And also legends _in side_ the plot._
> > Changed, made entire plot larger as well
> > Slide18
> > Move this slide after Slide15
> > Changed.
> > Slide19
> > _INside fig, mention "red line" is fit fun.
> > Added.
> > __ inside fig, p_T^reco -> p_{\rm T, jet}^{reco} ; 12.5 -> 12.5
> > GeV/c_
> > Changed.
> > __ you did not mention anywhere before what is "R"? And what jet
> > _R
> > you
> > are_ going to _do measurement_?_
> > It is labeled on the plot, and I will discuss it further on the
> > following slide.
> > __ what is v_{2}^ch? Need to mention _it charged_ jet v2. I
>  would
>
> > suggest_
> > to use $v_{2}^{\rm ch, jet}$; And the same about v_{2}^ch,abs
> > Changed.
> > Slide20:
> > Before slide20, you need to discuss different jet v2 (all, hard
> > core,
> > matched jet) and their spectra showing side-by-side
> > I'm not sure I understand why?  I think that was a good check to
> > make
> > and certainly worth having in the backup, but the measurement
> > being
> > presented is jet v2 using the hard core matching criteria, the
> > need
> > for which is motivated earlier in the talk.
> > Slie21:
> > _  "Jet v2 is a exciting measurement for determining the
> > path-length
> > dependence of jet quenching" -> This statement is fine to
> > motivate.
> > But
> > for your conclusion this may not be relevant. Because we don't
> > have
> > jet
> > v2 measurement for different path length/system size with the
>  same
>
> > kinematic coverage. And you did not discuss what is the strategy
> > for
> > your measurement unless you plan to do the same in AU+AU.
> > _"Jets which are in plane interact with a different amount of
>  the
>
> > QGP
> > than those out of plane" Not sure how do you get this conclusion
> > from
> > your measurement.
> > I have updated my conclusions to better reflect the points I
>  wish
>
> > to
> > make and where I will go next with this analysis.
> > Thank you
> > Nihar
> > On Thu, Oct 6, 2022 at 1:34 PM Yi Yang <yiyang0429 AT gmail.com>
> > wrote:
> > Dear Tristan,
> > Thanks a lot for the reply and the updated version.
> > They look very good to me.
> > Let's wait for your study and the decision on the preliminary
> > results!
> > Cheers,
> > Yi
> > On Thu, Oct 6, 2022 at 3:26 AM Tristan Protzman
>  <tlp220 AT lehigh.edu>
>
> > > wrote:
> > > Hi Yi,
> > > Thank you for the feedback!  I have uploaded an updated version
>  and
>
> > > addressed your comments below.
> > > - p4: Are the sub-bullet for the 3rd bullet and the 4th bullet
>  the
>
> > > same?
> > > Yes, I have removed that redundancy.
> > > - p6: toy mode --> toy model
> > > Fixed.
> > > - p9: Just for my own education, could you please tell me why
>  A_j
>
> > can be less than 0 (I am assuming pT^1 and pT^2 are leading and
> > subleading jet pT, respectively, is it correct)?
> > Yes, (pT^1, pT^2) is the (leading, subleading) jet pT.  The red
> > points are the measurement of A_j using only hard cores.  This
>  is
>
> > where leading and subleading are determined, thus no points
>  below
>
> > 0.
> > However, after matching is done, leading and subleading are not
> > recalculate, so it is possible for the subleading hard core to
>  match
>
> > > to a jet with more momentum than the leading hard core does,
> > > resulting in negative A_j.  There are a few ways this could
>  happen.
>
> > > The subleading jet could contain a larger soft component than
>  the
>
> > leading jet, thus when added to the hard core the magnitudes
>  flip.
>
> > > Additionally, because of the fluctuating background the leading
>  jet
>
> > > could be over subtracted and the subleading jet under
>  subtracted,
>
> > again flipping the relative magnitude.  This would not affect
>  the
>
> > hard core since background subtraction is not done on that
> > collection.
> > - p15: It would be good if you can provide more information for
>  the
>
> > > subdetectors, for example eta and phi coverage...
> > > I added more information about each system and labeled the
>  picture.
>
> > > - p18: Jet v2 not feasible --> Jet v2 is not feasible
> > > Changed to Jet v2 was not feasible
> > > Cheers,
> > > Tristan
> > > On Wed, Oct 5, 2022 at 1:59 PM Yi Yang <yiyang0429 AT gmail.com>
>  wrote:
>
> > > Hi Tristan,
> > > Thanks a lot for the nice slide. I have some
>  suggestions/comments
>
> > for your consideration.
> > - p4: Are the sub-bullet for the 3rd bullet and the 4th bullet
>  the
>
> > > same?
> > > - p6: toy mode --> toy model
> > > - p8: Title: Hardcore --> Hard core
> > > - p9: Just for my own education, could you please tell me why
>  A_j
>
> > can be less than 0 (I am assuming pT^1 and pT^2 are leading and
> > subleading jet pT, respectively, is it correct)?
> > - p15: It would be good if you can provide more information for
>  the
>
> > > subdetectors, for example eta and phi coverage...
> > > - p18: Jet v2 not feasible --> Jet v2 is not feasible
> > > - Since we are not settled with your preliminary results yet, I
> > > will comment on p20 and p21 later. :-)
> > > Cheers,
> > > Yi
> > > On Thu, Oct 6, 2022 at 12:36 AM Tristan Protzman via Star-hp-l
> > > <star-hp-l AT lists.bnl.gov> wrote:
> > > Hi All,
> > > I submitted this material for review last week, but it seems to
>  have
>
> > > been lost somehow, so I am resending it.
> > > Cheers,
> > > Tristan
> > > On Wed, Oct 5, 2022 at 12:33 PM webmaster--- via Star-hp-l
> > > <star-hp-l AT lists.bnl.gov> wrote:
> > > Dear Star-hp-l AT lists.bnl.gov members,
> > > Tristan Protzman (tlp220 AT lehigh.edu) has submitted a material
>  for
>
> > a
> > review,
> > please have a look:
> > https://drupal.star.bnl.gov/STAR/node/61264
> > Deadline: 2022-10-11
> > ---
> > If you have any problems with the review process, please
>  contact
>
> > webmaster AT www.star.bnl.gov
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> > https://lists.bnl.gov/mailman/listinfo/star-hp-l
>  _______________________________________________
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> --
> Rosi Reed
> RHIC/AGS UEC member
> Associate Professor, Physics Department
> Lehigh University
> (610)758-3907
> 16 Memorial Drive East Office 406
> Bethlehem, PA 18015
> she/her/hers
> Links:
> ------
> [1]
> https://urldefense.com/v3/__https://physics.fjfi.cvut.cz/files/predmety/02RQGP/zs1617/GyulassyPluemer.pdf__;!!P4SdNyxKAPE!Ez8frSqNJbBBgywunqqEJilI-3bnKgpyx5zAD_HBfZVBjsvOPutfr1MohqqCsvBHTEzGzKHaD71BzzjqNgYSMSxtUg0$
> --
> Rosi Reed
> RHIC/AGS UEC member
> Associate Professor, Physics Department
> Lehigh University
> (610)758-3907
> 16 Memorial Drive East Office 406
> Bethlehem, PA 18015
> she/her/hers
> Links:
> ------
> [1]
> https://urldefense.com/v3/__https://physics.fjfi.cvut.cz/files/predmety/02RQGP/zs1617/GyulassyPluemer.pdf__;!!P4SdNyxKAPE!DAjTvNqBnrDN15MQ9KFyfzsr7tyaPU93FxKstErQdeUayvJRIOKJqvPWleLmN7577Py7tYbZP1_UGMeIwR6tJr93nKs$
> [2]
> https://urldefense.com/v3/__https://arxiv.org/pdf/0911.3130.pdf__;!!P4SdNyxKAPE!DAjTvNqBnrDN15MQ9KFyfzsr7tyaPU93FxKstErQdeUayvJRIOKJqvPWleLmN7577Py7tYbZP1_UGMeIwR6tF1O-DZQ$
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