STAR HardProbes PWG

["Mooney, Isaac" <isaac.mooney AT yale.edu>]

Hi Neil and PAs,

For now I’m focusing my comments on the analysis note (see below), since I will be the PWG rep for this analysis and can give detailed comments on the paper after GPC formation. Hopefully this saves a bit of time getting the ball rolling due to Neil’s time constraints. I did do a quick read-through of the short paper as well just to make sure that it’s acceptable for GPC formation. I had some comments, but nothing preventing it moving to the next step, so I’ll hold off for now until I do a more detailed read-through at that time. We’ll see if Qian or Nihar have any major comments, but mine on the analysis note can be addressed in parallel with GPC formation which I think the analysis is ready for.

Thanks, and congratulations on advancing this high-quality analysis to this stage,

Isaac

79. How was 600 MeV chosen for the D0 daughters?

83. What is the nhitsdEdx cut used?

139. Sorry, just to make sure I understand, do you mean "all the jet constituents" except the D0 candidate, or really "all" jet constituents? I'm not sure why we wouldn't assign the proper mass in a situation where we're fairly sure of that particle's identity.

Fig. 1.5. I'm a little surprised that the weights are quite this negative in the background regions. But I guess this is due to a negative covariance and may not be a problem as long as the sum of sWeights in a given control variable bin is non-negative? Are there any such bins in the analysis where the sum is negative?

168. Is the reason there is any discrepancy at all entirely due to sPlot? Or are there any other differences (e.g. selection criteria, binning, failed jobs, different random seed, etc.)?

189. When you apply the hadronic correction, have the K and pi already been removed from consideration so that their track pTs are not subtracted from the tower ETs, or do you include them for this correction and remove them later? I would assume the latter except you've already mentioned in the text that they are removed.

Fig. 1.10. I can understand that because sequential recombination algorithms in general don't have to have an exact cone shape at the jet radius (although anti-kT is fairly circular), you could technically get D0s beyond DeltaR = R_jet. But DeltaR = 0.6 would be pretty surprising to me. Or do the entries in the bin stop at just a hair past 0.4, and the bin is just wider than necessary?

Figs. 1.10 - 1.12. I'm a bit surprised the z_jet^uncorrected plots look identical between Figs. 1.11 and 1.10. Looking at the 40-80% distributions as an example, I'm not able to spot the difference. I would have thought in the tails, either positive or negative, there should be some difference, despite the much lower counts of D0jets with D0 pT > 5 GeV, since the D0 pT being larger should contribute to a larger z. I see from Fig. 1.12 that actually the tails drop off much more dramatically for the larger D0 pT so I guess my intuition was wrong. Should I think of this as being caused by the fact that jets with a large pT D0 are much less likely to be background jets, which decreases counts both for negative and large-positive z? 

Corollary 1: is the jet pT fixed for the D0 z plot, or is it integrated over jet pT? [Whatever the answer, it would be good to specify somewhere in the analysis note, similarly for the DeltaR as well].

Corollary 2: is there any requirement on number of jet constituents? Is it possible to have a jet that is just the D0 if it passes all other requirements? I think we talked about this during a PWG meeting and you mentioned that these one-particle jets were included (so there's a separate category included in the 0.9 - 1 z bin which are identically 1.0) [I just read the paper and see this is the case]. Have you checked the effect that it has on the results (pT, z, DeltaR) to disallow these jets?

Fig. 1.14. I think I understand why the distribution in raw z is bimodal for the 40-80% centrality selection for the previous plots, but do you have a good intuition for why it isn't continuous in the 10-40% case for R = 0.2? And where are the bins just below 0 for the 40-80%?

275. When you say "already corrected for the D0 reconstruction efficiency at this stage" do you mean there is a step between the previous and this one of applying D0 efficiency?

278. I'm a little confused -- you say the D0 is reconstructed at detector-level but the daughters are not? And then you use momentum resolution to reconstruct it? Can you clarify what you mean here?

Fig. 1.20 - 1.22. It would be great if the y-axis of the ratio plots could be zoomed in a bit so any potential shapes could be observed. Something like 0.5 - 1.5 should work in all cases given how excellent the agreement is.

374. Are fakes also weighted by this factor? What, if anything, is done for misses?

390. Can this statement be quantified somehow? Can you show the correlations between the three observables: pT, z, and DeltaR for example? Or show the 3D unfolding result even though statistics are poor? Or some other way.

415. Hijing -> Pythia? Or is Hijing used somehow?

431. "DCA < 3 cm", yes? 0.2 cm seems like a fairly minimal variation. Do statistics really significantly suffer for e.g. a 2 cm cut as a variation?

462. You say that only the uncertainty on R1 is quoted but also say the uncertainty is given by the second term on the RHS of eq. 1.7. How are these both true?

Fig. 1.32.

This probably demonstrates that I'm not as familiar as I should be with the previous D0 analysis, but can you explain why you have uncertainties related both to D0 reconstruction efficiency with and without vertex correction?

When you say "peripheral (right)", you actually mean "bottom" in this case, right? Since the plot has wrapped to the next row. Just want to make sure I'm not mixing up midcentral and peripheral.

Fig. 1.65. Shouldn't the full jet pT spectrum be harder than the charged jet spectrum? It looks like it is until the last one or two bins in all cases, which is a bit odd to me.

On Nov 9, 2024, at 14:49, Diptanil Roy <roydiptanil AT gmail.com> wrote:

Dear conveners and HP-pwg,

We now have a proposed version of the STAR D0 Meson Tagged Jets paper drafts available. The links for the paper drafts, analysis notes, and the paper webpage are below. We request to form a GPC to get this work over the line.

Please send your comments and feedback.

Paper Drafts

 

Short Paper: Link 

Long Paper: Link

Analysis Note Link

Paper Webpage Link

PWGC Preview Link

Thank you to everyone who helped with this analysis since the beginning.

--

~ Neil on behalf of the PAs (Neil, Matt, Sevil, Joern)