sPHENIX discussion of physics

["Dean, Cameron" <cdean AT bnl.gov>]

Hi all,

Here are the minutes of todays meeting:

Introduction – Conveners

Cameron – We’re seeing the first collisions in sPHENIX so we should start preparing to see the first data. Chris has been reprocessing our simulations with the latest tracking software. Zhaozhong has also fixed a bug in KFParticle for the magnetic field which was merged this week.

D0-jets – Xuan

Slide 6 – Jin – In the double Crystal Ball, the core is very sharp. My guess is they are track-dominated jets which probably have an associated calorimeter component. The peak of this distribution is capturing the track resolution. Also, the tail is to the left of the peak which means there is less truth than reco energy.

                Xuan – Your thoughts are the same as my ones here

                Antonio – On the tail, there could be pileup in the reco containers but not in the truth so the larger reco. momentum could be due to this.

                Xuan – I selected simulations without pile-up but we can check the setup again to confirm

                Jin – We can also go through the truth record to see what is in the jet

 

Slide 7 – Jakub – We see the tail in the p_truth – p_reco distribution in the lower jet momentum bins. Do we apply a D0 pT cut?

                Xuan – Yes, we have a cut of D0 pT > 1.5 GeV

                Jakub - What about applying an upper cut at the maximum of the bin so D0 pT <= jet pT in both the truth and reco values.

               

                Jakub – Do we see the same effect in the pT distributions that we see in the p distributions?

                Xuan – Yes

 

Slide 12 – Aditya – The peak position of the low pT is lower than the intermediate and high pT distributions. Do we understand why?

                Xuan – I think this is mainly from the generator where we have softer low pT components.

 

Slide 13 – Zhongling – The points on the plots are the mean of the fit results?

                Xuan – No, they’re from the mean of the histograms

 

                Jakub – To Jin and Cameron. Could the bias come from the simulation setup?

                Cameron – In the pythia steering card, we do have a min. pT-hat requirement on the D0 but I can’t think of how this would translate to a bias in the jet pT as well

                Jin – There is always a bias in a D0-jet sample. We need to be very careful. In this plot though, we should not be so sensitive to the bias. We have a truth trigger jet cut of R > 0.4 and pT > 7 GeV. We don’t have any statistics below these values. We do have a q-hat cut as Cameron mentioned but we should be capturing a large sample of the phase space. I think what we see is a genuine detector effect that shows up at low pT.

                Joe – We need to invest some effort into what the particle flow algorithm is doing. We may be double counting at low pT

 

Summary – Dillon – I have plans to work on something similar with D0-jets over the summer (Dillon has joined the D0-jet mattermost channel to get up to speed since the meeting). Do you reconstruct the D0 first before handing them to the jet algorithms?

                Xuan – We first loop through the tracks to select kaon and pion candidates then combine them to make a D0 and apply more cuts. This D0 is used as a seed and jets are formed around it.

 

                Antonio – It is possible that we’ll have to cut at a higher pT than we would like but we should still keep working on the low pT reach

 

                Cameron – There is a peak in the truth jT for both the high and low pT jet samples which isn’t there in the reco distribution. Is this understood?

                Xuan – You can also notice a peak at the edge of the z_proj distribution so we may be cutting on the edge of something. We can investigate further.

 

                Jin from Dennis – As we move to data taking, our WG will need to make strong contributions to the commissioning, such as with K_s0 reconstruction. D0-jet will be a good candidate for commissioning and we may get a shot at it this year but certainly needs to be in good hsape for next year. Our first D0-jet measurement will likely be with calo. jets and matching tracks. We should get a group together for calo-based jets.

 

From: "Dean, Cameron" <cdean AT bnl.gov>
Date: Friday, May 19, 2023 at 12:13 PM
To: "sphenix-physics-l AT lists.bnl.gov" <sphenix-physics-l AT lists.bnl.gov>, Rosi Reed via sPHENIX-HF-jets-l <sphenix-hf-jets-l AT lists.bnl.gov>, Anthony Frawley via sPHENIX-upsilons-l <Sphenix-upsilons-l AT lists.bnl.gov>
Subject: Reminder: 05/19/23: Next Heavy Flavor and Quarkonia meeting

 

Dear all,

We will meet in a few hours at 3pm ET.

Speak to you all soon,
Cameron, Jin, Marzia and Tony

 

From: "Dean, Cameron" <cdean AT bnl.gov>
Date: Wednesday, May 17, 2023 at 5:11 PM
To: "sphenix-physics-l AT lists.bnl.gov" <sphenix-physics-l AT lists.bnl.gov>, Rosi Reed via sPHENIX-HF-jets-l <sphenix-hf-jets-l AT lists.bnl.gov>, Anthony Frawley via sPHENIX-upsilons-l <Sphenix-upsilons-l AT lists.bnl.gov>
Subject: 05/19/23: Next Heavy Flavor and Quarkonia meeting

 

Dear quarkonia and heavy flavor enthusiasts,

We will have our next topical group meeting on Friday, May 19^th 2023 at 3pm ET. On the agenda we have:

 

• D0 jet update – Xuan Li, Los Alamos National Lab

 

The indico link is https://indico.bnl.gov/event/19548/
You can join the meeting from https://bnl.zoomgov.com/j/1613938007?pwd=QjYzUnpYQ2xNZWZLSy9qd3Z4dFpzZz09

We look forward to talking to everyone on Friday,

Thanks,
Cameron, Jin, Marzia and Tony