Kaon_LT Experiment

                Apr 13/23 PionLT/KaonLT Analysis Meeting Notes

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                              (Notes by GH)

                    Today: KaonLT will be discussed first

Please remember to post your slides at:

https://redmine.jlab.org/projects/kltexp/wiki/Kaon_LT_Meetings

Present

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Regina - Ali, Alicia, Love, Junaid, Vijay, Garth

CUA - Tanja, Richard

FIU - Pete

At GHP: Stephen, Nathan, Dave G

Regrets: Julie, Jacob

Richard Updates

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PID investigation

- now doing a proton subtraction, but normalizing to the beam charge

- getting a large over-subtraction of the data

   - GH: need to normalize to the size of the omega+p peak, not the charge

   - the idea is to use the data to understand the MM-shape of the proton

     leakthrough

   - the efficiency of the proton cut can be low, need a clean proton sample to

     be sure you aren't subtracting Kaons

   - the differing cut efficiency for K+ (with leakthrough) and protons (with

     minimal contamination) can be large, so normalizing only to beam charge

     won't work

- deal with pion leakthrough subtraction the same way, normalizing to the pi+n

  peak

- Ali and Richard meeting tomorrow at 16:00 Eastern to discuss PID

Lumi Issues

- no report today, will wrap up loose ends soon

Ali Updates

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Pion PID study for all Q2>2.0 data, five settings in total

- uses HGC to remove K+ leakthrough (keep NPE>1.5 events)

   - other cuts: acceptance, e-pi cointime, aerogel

- analyzed so far: low epsilon (spring 2019), high epsilon (fall 2018) still

  running

- MM spectra look clean, even up to Q2=5.5, looks like no K+ leakthrough

  subtraction will be needed, which is good news

- GH: it will be important to study PID cut efficiencies as well, so that we

  are sure we aren't using a cut that leads to a large systematic uncertainty

   - AU: HMS Cer+Cal have stable effs

         SHMS aerogel efficiency also good

         Tracking has rate-dep efficiency we will calculate run-by-run

   - The real issue is the HGC efficiency, no hole cut applied yet

      - need to implement the HGC hole cut, meeting tomorrow will discuss this

      - two possibilities:

        a) divide HGC into 2 sections, remove hole with eff<75-80%, correct the

           rest for inefficiency

        b) divide HGC into 3 sections, remove eff<50%, correct 50-80%, 80-100%

           regions separately

      - it would be easier to implement 2 sections, at least for pi+ analysis

        but we need to do study to check

      - also need to apply same hole cut to SIMC

      - RT: we have the algorithm from Peter B, need to implement it

   - once the HGC hole cut is implemented, it will be interesting to see if

     Alicia notices any BSA difference with it, particularly the 2nd t-bin,

     which always looks anomalous

- CoinTime also used to select PID

   - GH: maybe we need to apply a CT cut efficiency

   - use the HGC and aerogel to get a clean event sample, then plot CT for

     these events to get a better idea of a good cut for pi+, K+ analyses

   - so far, the CT plots that were made were without HGC cut, so the

     contamination from other channels is larger

   - the cleaner sample will enable the CT cuts to be optimized, particularly

     for K+ analysis, which has contamination from both pi+ and proton sides

- TH: in Fpi-2 she did a study, and determined that a correction wasn't

     required.  Need to do a similar study here.

   - CT resolution is worse than in Fpi-2

- For K+ almost certainly we need to apply a correction

- For Vijay's low Q2 pi+ analysis, the study needs to also be done, but should

  be quick and the correction small (if at all)

- Ali will have to do separate studies for low and high epsilon data, due to

  differing conditions

- GH: Also we should do a quick check if RF cut needed or not

   - AU should check if pi+ MM spectrum changes shape (particularly in Delta

     region) with and without RF cut

   - if shape does not change, irrespective of yield change, then RF cut

     probably not needed

   - K+ may be a different situation than pi+

Vijay Updates

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Data/SIMC plots for each t-bin

   - 8 t-bins, 16 phi-bins

   - mid epsilon at Q2=0.38 shown

- Plots of Data/MC ratio versus phi-bin for each t-bin

   - see clear oscillations (interference terms wrong in model), but overall

     surprisingly close to R=1

- GH: don't worry about the ratios for now, we need to be check instead if the

  code is working properly

   - for example, do the error bars propagate correctly from one SHMS setting

     to combined 5 SHMS settings

   - at higher -t, we see phi-bins which have much worse statistics than

     others.  This is presumably due to incomplete phi-coverage at higher -t,

     but we should be sure

   - plot R vs phi-bin for each SHMS setting separately, and compare to the

     combined phi distribution to see if it all makes sense

Shows a few sample SHMS xptar, yptar plots

   - Green=Data, Blue=SIMC

   - general agreement looks good

   - still working on other plots

- GH: you will find it more convenient to make a PDF of several plots on a

  page, sorted by theme

   - this will let you more quickly investigate if things are looking okay as

     you do the iterations

Next 2 week plan is to finish the plots and initial yield study

EIC Meson WG Discussion

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- TH: next meeting is Thur April 20 @ 9:00 Eastern

   - we should discuss next plans, including a future paper

- GH: has some questions on how new ePIC WG structure will work

   - seems to be more detector focused, less on the physics than before

   - in that scenario, the Meson WG will become even more important

- should include JLab 22 GeV as well as 2nd detector issues, not just ePIC

Next Meeting

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- Thur Apr 20 @ 16:00 Eastern/14:00 Regina/13:00 Pacific

- PionLT will go first