STAR HardProbes PWG

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

Date: 06/07/2024

Participants: Diptanil Roy, Sevil Selur, Hanna Zbroszczyk, Prithwish Tribedy, Isaac Mooney, Nihar Sahoo, ShinIchi Esumi, Ting Lin, Xiaoxuan Chu, Yi Yang, Sooraj Radhakrishnan, Barbara Trzeciak

Title: D0 Meson Tagged Jets In Au + Au Collisions at √sNN = 200 GeV

PAs: Diptanil Roy, Matthew Kelsey, Sevil Salur, Joern Putschke

Target journal: PRL + PRC

Proposal page: https://drupal.star.bnl.gov/STAR/blog/droy1/D0-Meson-Tagged-Jets-Au-Au-collisions-200-GeV

Presentation: https://drupal.star.bnl.gov/STAR/system/files/D0Jets_Diptanil_PWGCPreview.pdf

The PWGC panel previewed a paper proposal from HP PWG. The panel found that the analysis is mature and results are important and interesting, and the paper should move forward. The journal choice was also found to be appropriate. The following points were discussed.

Q: slide 9: Why is z larger than 1?

A:  It’s because of the average background subtraction.

Q: Figure 1 and 2: if we sum Figure 2 two cases we would get Figure 1 ? Then why the sys. unc. at low z are different?

A:  Yes, that’s correct. But the unfolding is done separately, and the sys. uncertainty can be driven by fluctuations. We can still look at this more closely. 

Q: When you do embedding, you don’t pass PYTHIA jets via embedding?

A:  We do, there are detector effects in jets. 

Q: What could be the impact compared to the usual embedding approach?

A: There shouldn’t be any, we don't embed so many particles.  

Q: What could cause the z dependence of the suppression? Are there similar measurements from LHC?

A:  There are no LHC measurements in HI collisions. There are two competing mechanisms, radiative and collisional energy losses which are differently mass dependent. But it’s more of a speculation. We are in contact with the theory people to gain more insight. 

Q: You should then get the average of a single D0 meson.

A:  It’s not exactly like this, as we have jet pT cut > 5 GeV/c. But without the jet cut the results are consistent and single D0 RAA and R_AA of D0-jet for R=0.2 are consistent.

Q: Have you looked at the radial profile with R=0.2?

A: The behavior is consistent but with large uncertainties.

Q: Figure 4: why to make the ratio w.r.t smaller radius? You have stat. better results for larger R.

A:  It’s just how LHC showed, but we can redo this.

Q: Have you tried to look at your observables vs centrality (N_part)?

A:  We haven’t explored that.

Q: Do the models describe the single D0 RAA?

A:  They should do a decent job, but we will cross check with them.

Q: Why do you compare to models only at the ratio (R_CP) level?

A: We will add them on the observable plots, theorists are working on correct normalization.

Q: Figure 3: maybe you can add ratios between different R values, to explore the non-perturbative effects ?

A:  We can look at this.

Q: There is no big distinction between your PRL and PRC physics. Can we make a strong PRL case, can we combine for one PRL submission, or go to PRL?

A: D0-jet z in heavy-ion collisions has never been measured. The fragmentation part is the novel part therefore we aim for PRL, and in PRC we’re providing measurements that were also done at LHC. We will make the physics arguments in the PRL submission very clear and strong.