sPHENIX discussion of physics

[Cameron Thomas Dean <cameron.dean AT cern.ch>]

Dear all,

 

I’ve written up the minutes of today’s meeting:

 

sPHENIX December workfest, commissioning analyses – Cameron Dean

 

• On HF&Q modules proposed to be developed at the workfest

 

Jin – We would require a large DCA on tracks for the K-short and Lambdas as their pT is lower

Cameron – This could be added as a selection. I thought we already had some functions in the track fitting that calculate this for us but we can always add functions to the module

 

Jin – It could be useful to have a D0 study as well

Cameron – I thought about putting this down as a 5^th analysis but my worry was the statistics would be too low for “commissioning”

 

Jin – We could also filter for low centrality to reduce the amount of combinatorial

Cameron – Yes, this is a good suggestion. I thought about adding the centrality value for each event to the pico-DST so we could make centrality-dependent distributions but this could be useful for the initial studies to only look at low central events.

 

Jin – How about looking at converted photons to help quarkonia

Cameron – (I misunderstood the question and thought we were discussing pi0 for the calorimeter calibration). Jin clarified it was for quarkonia

 

Marzia – There is a large difference between a pico-DST for upsilons and for K-shorts. Upsilons need electron-ID and we see good separation for electron pT > 2 GeV, a factor of 100 reduction from e-ID and a further 10 from pT. There will be lots of pairs made for a K-short analysis from pion pairs and the low mass.

Tony – That’s true but the DCA cut will reduce a lot of the combinations so the file size would be similar.

 

Chris – You will need PID for all these analyses.

               Also, what is “one week of data”? For commissioning we will have a much lower rate than 15 kHz.

Cameron – (OFFLINE) I should look at the cross sections and expected run time/delivered lumi over the commissioning to understand rough expected yields for all channels

 

Tony – A K-short and Lambda analysis would fit somewhere between our alignment and high lumi running

             We need to look at our tracking for K-shorts, it’s important to understand how the large DCA requirement will affect our tracking efficiency.

 

Marzia – It will take months to build up large statistics but we need the pDST to build those statistics to avoid running over the full DST data set.

Tony – We can always come back later to realign if we have the right information in the pDST for this. We would make the pDST with cuts but what are those cuts? Do we know they’ll be good while we’re also figuring out the alignment.

 

V0 analyses - Daniel Lis, Dennis Perepelitsa

 

• On the K-short peak

 

Tony – Do you apply any cuts here or is this all combinations. We’ve looked at K-shorts and seen a huge signal-to-background ratio

Dan – There are some cuts added

Cameron – The flight distance chi2 and track IP chi2 cuts here will reduce a lot of the prompt background and combinatorial.

 

Dennis – How did you decide on the cut values?
Dan – There was a KFParticle tutorial on D0 and I used that with an understanding that K-shorts would be further from the PV

Joe – It would be useful for the tracking group to see the distributions of the variables you are using

 

• On the decay length distributions

 

Tony – The decay length distribution indicates that the K-short is decaying too quickly.

Cameron – Is this the raw output of the KFParticle decay length branch?

Dan – Yes

Cameron – I’ve never been convinced on the units for the decay length from KFParticle

Tony – If this is mm then this may be OK

Cameron – (OFFLINE) I checked the code and an example output file. The units are in cm

 

Zhaozhong – Could you use the relative ratio between the K-short and Lambda to check that they are decaying correctly?

Cameron – That’s a good suggestion

Tony  – You cut off the true distribution due to the MVTX hit requirement so it’s not as simple a check

 

Jin – It would be useful to study the tracking and acceptance efficiencies similar to what Thomas Marshall has done for D0.

      – The decay length difference could make sense as you have a different boost between K-short and Lambda

             –  It could be useful to look at the AuAu central and peripheral simulations to figure out what we expect to see in real data

 

EvtGen update – Zhaozhong Shi

 

       Jin – The QA module here looks at the truth variables so we will accept only perfect agreement for this

             – We can follow up on the EvtGen errors offline

 

     Chris – You should talk to Anthony  about the simulations. He put a macro together that uses a simulation without having the whole sPHENIX           detector and framework in it. He found some decay particles go along z = 0 so you can lose them if you take a set of the sPHENIX setup which could cause some of the effects you see with events in the 0^th bin

 

      Cameron – Slide 4, is the decay time distribution inclusive or exclusive D0 decays?

      Zhaozhong - Inclusive

 

From: Cameron Thomas Dean <cameron.dean AT cern.ch>
Date: Thursday, November 10, 2022 at 8:58 AM
To: "sphenix-physics-l AT lists.bnl.gov" <sphenix-physics-l AT lists.bnl.gov>, "sphenix-hf-jets-l AT lists.bnl.gov" <sphenix-hf-jets-l AT lists.bnl.gov>, "sphenix-upsilons-l AT lists.bnl.gov" <sphenix-upsilons-l AT lists.bnl.gov>
Subject: FW: HF/Q topical group meeting tomorrow, Thursday November 10th, at 10 am EDT

 

Dear colleagues,

This is a reminder that we will have a quarkonia and heavy flavor meeting in approximately 1 hour (10am ET)

Cheers,

Cameron, Jin, Tony and Marzia

 

From: Cameron Thomas Dean <cameron.dean AT cern.ch>
Date: Wednesday, November 9, 2022 at 11:40 AM
To: "sphenix-physics-l AT lists.bnl.gov" <sphenix-physics-l AT lists.bnl.gov>, "Huang, Jin 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: HF/Q topical group meeting tomorrow, Thursday November 10th, at 10 am EDT

 

Dear friends,

 

Our joint HF/Quarkonium TG meeting will be tomorrow, Thursday November 10th, at 10:00 AM ET.

 

We have the following talks on the agenda:

• Introduction: co-convenors
• sPHENIX December workfest, commissioning analyses - Cameron Dean
• V0 analyses - Daniel Lis, Dennis Perepelitsa
• EvtGen update - Zhaozhong Shi

 

For those at BNL, we have booked room 2-219 in building 510 for the meeting.

 

For those that are remote or want to connect on zoom, please join us via:

https://indico.bnl.gov/event/17739/

https://bnl.zoomgov.com/j/1613938007?pwd=QjYzUnpYQ2xNZWZLSy9qd3Z4dFpzZz09

 

We look forward to meeting you then.

 

Cameron, Jin, Tony and Marzia