Kaon_LT Experiment

                Oct 23-24/25 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

Thursday: Present

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Regina - Garth Huber, Nathan Heinrich, Muhammad Junaid, Alicia Postuma,

   Nermin Sadoun, Vijay Kumar

CUA - Chi Kin Tam, Tanja Horn, BC Manoj

JLab - Dave Gaskell

Virginia - Richard Trotta

Ohio - Julie Roche

Richard

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KaonLT - checking phi calculation in SIMC

- SIMC version of phi_lab goes from -pi to +pi

  - if phi<0, add 2pi.  It's important not to add pi to all angles, as this

    screws up the 0 to pi part.

  - thetapq, thetapqi - reconstructed and vertex theta_pq quantities

  - thetacm - vertex angle in CM frame

- many thetacm values are zero or NaN even though other variables are fine

  - still investigating

  - Vijay: saw the same thing, seems that thetacm is not output for every event

  - Junaid: does not see this problem

    - *NB* it's important to add this variable to results_write.f in SIMC

    - check with Junaid for instructions, if needed

- Peter Bosted's email about phi

  - Dave did a quick test, the difference between old and new phi calcs is very

    small, both definitions appear to be consistent

Chi Kin

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Q2=4.4 data analysis

- comparing #counts after cuts w/Richard

  - purposefully removed pion and random subtractions, still have a yield

    difference

  - effective chage is same for Left, Center but different for Right

    - looks like some runs were missed in the replay

  - have not yet compared HGC hole cut effects

Alicia

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u-channel analysis

- PYTHIA simulations

  - found that Pythia does a poor job for the Q2=3.0, W=2.32 setting

  - MM distributions have extra structures not seen for higher W settings

  - looked at correlations of MM with other variables

    - e.g. additional lines appear in MM vs hsyptar

    - it really looks like a resonance or some exclusive process is included

- *NB* Garth: suggest to compare Pythia to data, perhaps the data have the same

  structrues at this W?

  - if not, then try comparing to Xphsp simulation, at this lower W the MM

    coverage of the simulatino might be sufficient

Junaid

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PionLT analysis

- replayed all PionLT data after Nathan's new report files (for CoinBlocking

  corr)

- will look into phi issue next

Nathan

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PionLT Lumi analysis

- working on a write-up of the results, hopes to share a draft next week

--

Friday: present

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Regina - Garth Huber, Alicia Postuma, Nathan Heinrich, Nermin Sadoun,

   Muhammad Junaid, Vijay Kumar, Nacer Hamdi

York - Stephen Kay

Glasgow - Kathleen Ramage, Rachel Montgomery

JLab - Dave Gaskell

CUA - Sameer Jain, Tanja Horn, BC Manoj

JMU - Gabriel Niculescu

Ohio - Julie Roche

Virginia - Richard Trotta

FIU - Pete Markowitz

Nacer

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KaonLT Q2=0.5 analysis

- following up on last week's discussion about high sensitivity to

  phi-dependence when adding interference terms to LT-separation

  - compared phipqi to phipq from SIMC

  - for Center setting, distributions are fairly similar, except that big pekas

    in phi-dists are shifted away from 90deg, 270deg

  - for Left, Right settings, distributions are offset from each other by

    180deg

  - *NB* this is because pi was added to all angles, instead:

    - for phi<0 add +2pi

    - for phi>0 leave unchanged

- working on Sigma yields

Gabriel

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KaonLT - looking at CoinBlocking correction

Sameer

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KaonLT - showed plots for CoinBlocking correction

- *NB* Nathan: need to get rid of weird peaks at -300 first, they look like

  they're due to a bad RefTime cut

  - look at T.coin.pTRIG1_ROC1_tdcTimeRaw, keeping in mind that triggers are

    different between KaonLT and PionLT

    pTRIG1(PionLT)=pTRIG4(KaonLT)

  - suggest to start by plotting the raw timing variables and selecting proper

    cuts

  - only after that is done should you select the cuts for the CoinBlocking

    correction

  - the wide cut needs to select the base of the full distribution

Vijay

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Summer 2019 PionLT analysis

- CoinBlocking correction: using a 135ns window

  - correction varies 87%-98% plotted vs Run Number

  - *NB* Garth: please plot it vs CoinRate, so we can verify the correction

    makes sense

    - Nathan: if the correction is good, it should go to unity at zero rate

- presents GH's fit of VGL model to initial results

  - sigT is much larger than Ackermann Q2=0.35 data

  - sigLT is opposite sign to Ackermann as well

    - Fpi-1 Q2=0.60 has same sign LT as Vijay, so difference appears to be

      Ackermann

  - VGL poorly describes the t-dependence of the sigL data

    - GH followed steps similar to Fpi-1 analysis in dealing with this, a

      significant model dependence uncertainty will have be assigned to the Fpi

      extraction as a result

- these preliminary results do not yet have:

  - CoinBlocking corr

  - pion absorption corr

  - *NB* Vijay also has to check aerogel tray cut in SIMC

    - Junaid: the data cuts might be buried in the replay script

Next Meeting

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New 2-meeting/week structure

- Thurs: Oct 30 @ 16:00 Eastern/14:00 Regina

  - PionLT will go first

- Fri: Oct 31 @ 11:00 Eastern/9:00 Regina

  - we will continue where we left off