Kaon_LT Experiment

                 Jun 13/24 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 - Garth Huber, Vijay Kumar, Ali Usman, Muhammad Junaid, Zach Sullivan

JLab - Dave Gaskell

FIU - Pete Markowitz

Virginia - Richard Trotta

CUA - Tanja Horn

Vijay

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MM cut study for low Q2 PionLT data

- scanned MM cuts from 0.972 to 0.988 GeV

- reanalyzed both data and SIMC with these cuts

- reran LTsep script, but did no iterations with model

- computed variation in sigL and sigT compared to standard MM cut at 0.980

- results show nearly zero variation in lowest -t bin, rising to ~5% for

  highest -t bin

  - calculated RMS of deviations (in absolute units) for all 8 cuts

- Dave: if the deviation is systematic between different MM cuts, cannot

  use the RMS to determine the uncertainty

  - however, the deviation seems somewhat random, signs flip too, so maybe RMS

    is okay

- no one else has any other suggestions

- Vijay will also look at deviations for sigLT and sigTT

Next steps

- computing RadFlag On/Off systematic

- investigate variations in XPtar YPtar cuts

Ali

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- spent a lot of time this week making plots for thesis, calibs, efficiencies,

  PID

- completed MM shape study for piDelta BSA, to show results next week

  - extracted BSA for all settings

  - will extract LT'

- in parallel with this, computing some systematic uncertainties related to MM

  fitting

  - variation in neutron fit

  - MC to data normalization

  - still has to look at MM cut dep to BSA result

- worked w/Nacer last week on Heep analysis, will show some plots next week

  - at last meeting, Nacer's low Q2 analysis agreed well w/ Richard

  - worked on 6.2 GeV Heep, also compares well w/ Richard

  - still looking at Cherenkov efficiency

     - Junaid's Cherenkov eff (~99.8% vs 97%) helps the discrepancy compared to

       Ali's eff, but the discrepancy still reamins at 6.2 GeV

- Dicussion on things that might address the discrepancy

  - *NB* Alternate Heep cross section parameterizations are available,

    e.g. Bill checked multiple Heep parameterizations in his thesis, since the

    Heep cross sections are less reliable at higher Q2, it would be a god idea

    to switch parameterization in SIMC and see what the effect is

  - Dave: is proton absorption included in the Heep analysis?

     - SIMC does not correct for absorption, only scattering

     - *NB* need to apply the correction to the Exp data

     - it could be a 4-5% correction, depending on kinematics

     - *NB* we had discussed this before, but it was forgotten, Richard and

       Vijay need to also determine a correction for pi/K absorption and apply

       it to physics data prior to doing LT-separations

  - Junaid: Zach applied 3 different Cherenov cuts in his PionLT analysis, gets

    efficiencies similar to Junaid

     - need to check if Cherenkov gas pressure changed between KaonLT and

       PionLT, this could explain the reason why the inefficiency is 10x less

       for PionLT

     - Dave: the same gas was used, but the pressure was changed

       - Burcu identified a light leak in the J/psi data, which caused a large

         inefficiency issue

       - the light leak wouldn't have been fixed until much later

     - *NB* Ali/Zach(?) should search hclog for info on on when the leak was

       fixed and what gas pressures were set

     - if we can't explain the discrepancy, we might have to take the

       difference between them as a systematic, which would be undesirable

     - if we can explain the discrepancy, then we have a good reason to apply

       different efficiencies to KaonLT and PionLT data, and the assigned

       systematic is much lower

 Richard

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KaonLT LT-sep iterations

- 1st iteration w/ new functional form for Q2=5.5

  - 2nd t-bin has highest statistics

  - has 4 t-bins now, probably should reduce to 3 t-bins

- some discussion on what minimum #phi-bins is acceptable

  - too few phi-bins makes it impossible to separate LT from TT

  - has 6 phi-bins now, which is also the minimum number that Marco had

  - Garth: a good way to find out what is the true minimum #phi-bins is to do

    an MC study similar to what Alicia did, and see what results in a reliable

    separation of LT, TT for different #bins

  - *NB* Richard will look into revising #bins, will contact Alicia as well

Junaid

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PionLT Heep coin analysis, 9 settings

- rechecked all files, found there was a momentum offset applied to the data

  prior to determining offsets

  - renalyzed data w/o offsets, GH generated new offsets

    - new offsets very similar values to before

- checking what sign of offset to apply, tried +/- sign momentum offsets

  - wrong sign offset gives results nearly identical to correct sign offset,

    presumably because the applied momentum offset is very small

  - Garth: the beam energy offset and the momentum offsets should be applied

    the same way, so you probably should check changing all 3 in the same way

Zach

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Working on PionLT efficiencies for Lumi analysis

- will discuss results w/ Nathan before showing

 Next Meeting

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*NOTE THE SPECIAL TIME*

- Next meet: Wed June 19 @ 15:00 Eastern/13:00 Regina

  - PionLT will go first