Kaon_LT Experiment

                 Jul 31/24 PionLT/KaonLT Analysis Meeting Notes

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                                (Notes by GH)

                     Today: PionLT 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, Nacer Hamdi, Ali Usman, Alicia Postuma, Nathan Heinrich,

   Muhammad Junaid, Vijay Kumar, Zach Sullivan

Virginia - Richard Trotta

Ohio - Julie Roche

CUA - Tanja Horn

JLab - Dave Gaskell (last half)

Nathan & Zach

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- Zach had a problem w/ python script in ALMA9.  Nathan and Junaid have not

  been able to fix it

- Junaid thinks there has been a change in python syntax, but can't figure it

  out, stuck for now

- *NB* Richard will take a look, probably an incompatibility between versions

  of python and pyroot that needs to be fixed

  - the same problem is likely to also affect Richard's analysis, so this is a

    high priority for fixiing

Junaid

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PionLT Heep Study - 9 beam energies

- investigating two issues

1) some EM distributions are broad

  - for all 2021 data, EM peak is sharp

  - for all 2022 data, EM peak is broader

  - checked raster parameters, there are multiple raster calibs for 2021, but

    only one for 2022 that Mark Jones posted, based on run 14809 @ 7.950 GeV

  - no raster issues were noted for 2022 run, so presumably a single raster

    calib is sufficient

  - GH and Richard: *NB* try looking at EM versus raster_x, raster_y

    - if there is a problem, EM will be correlated (tilted line) with respect

      to these variables

    - the plots that Richard recommends are:

      2D: (S)HMS EM vs delta

          (S)HMS PM vs delta

          SHMS delta vs HMS delta

          raster_x/y vs PM/EM

          raster_x vs raster_y

      1D: BPM target x/y

2) calculation of Heep COIN error

  - checked error calculations, was using weighted SIMC yield instead of raw

    SIMC counts in the error calculation

  - this makes a huge difference, MC errors now much smaller

Nacer

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Heep error checks

- worked with Junaid, found the problem by checking numbers step-by-step

Comparing Heep models in progress, to establish uncertainty in the MC

  prediction

Comparison of Nacer and Richard Heep yield ratios

- it is important that we understand why the Heep ratios deviate from unity,

  and perhaps understanding the difference between Nacer and Richard's ratios

  will shed some light on this

- *NB* Richard will re-run some scripts to recheck and understand the

   discrepancy

Alicia

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BSA paper update

- B-G Yu happy with latest changes, paper is ready for submission

- filled out fields on PRL server, will be submitted later today

Ali

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piDelta BSA analysis

- Garth asked to show BSA plots for all settings

Q2=2.1, W=2.95

- 2 t-bins, data very smoothly follow sine-curve fits

- BSA amplitude ~0.12, small errors

  Julie: *NB* can you please make residual plots of data-fit?  The fit actually

  looks too good, Chi-square<1

Q2=3.0, W=3.14, 2 t-bins

- errors a bit lager, fluctuation about sine curve gives Chi-square<1

Q2=3.0, W=2.32, 1 t-bin

- right SHMS setting had mroe stats than left, so errors vary with phi-bin

Q2=4.4, W=2.74, 1 t-bin

- errors a bit bigger, BSA amplitude ~0.15

Q2=5.5, W=3.02, 1 t-bin

- errors bigger, Chi-square clearly <1 for ALL plots

- errors are statistical only, systematics not yet included

  Julie: *NB* can you please send me exactly how you calculate your error bars?

  - maybe your errors are over-estimated, do not follow 2/3-rule

Next steps

- work on systematic uncertainties in progress

  - syst unc due to 2 types of fits, 2 studies

  - syst unc due to cut-dependence, 2 studies

Richard

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KaonLT LT-iteration fitting

- updated sigT functional form

- added t-dependence, t-trend of Ratios more uniform now, but more iterations

  needed as Ratios ~0.4

- Tanja found an old Fpi-1 log entry by Jochen Volmer, dated Mar 16/2000:

  - he tried a functional form for sigT of the type:

    a+b*(W-Wc)+c*(Q2-Q2c)+d*(W-Wc)*(Q2-Q2c)

  - this seems like a very nice function that could describe the variation of

    the cross section across the diamond, where the diamond center is at

    (Q2c,Wc)

  - tried fitting it as sig_UNS at high,low epsilon, just to see what results

    - b & c terms have significant t-dependence, d more constant

    - curiously, b & c have opposite t-dependences, but they're in orthogonal

      directions on the diamond, so not sure if this results in cancellation or not

  - looks promising, GH suggests to try this form for sigL and sigT, perhaps

    could use a linear t-dependence for b & c, given their strong t-dependence

Vijay

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Low Q2 PionLT volume cut systematic uncertainties for L,T,LT,TT

- varied delta, xptar, yptar by +/-10%, 6 cut changes in total per spectrometer

- SHMS-delta

  - no variation in sigL,sigT

- SHMS-xptar,yptar

  - sigL varies 0.1-0.8%, depending on t-bin

  - sigT varies 0.1-1.2%

- HMS-xptar,yptar

  - variations are similarly small

- HMS-delta

  - variations are much larger, sigL 28-90%, sigT 40-90%

  - *NB* we need to better understand what is going on here, unexpected

    sensitivity

  Dave: *NB* you might need to increase the SIMC event generation limits

  - plot delta,xptar,yptar for +10% limits and check

  - another thing to keep in mid is that the HMS delta matrix elements are less

    understood past 8%, so the +10% cut is past the well-understood acceptance

    - 7.2% (-10%) cut is more reasonable, but your results look similar for

      8.8%

    - *NB* suggest to look at Vladis Tvaskis' PhD thesis:

       - Vladis and Henk found that a small correction to HMS-delta was

         necessary, affected things at the few percent level

       - if this correction is not implemented in the analysis, then we should

         look at adding it

   - *NB* please make plots of focal plane and physics variables for delta-10%

      cut, so we can see if there are any large discrepancies between them that

      could explain the unexpected variation

 Next Meetings

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- Note the special time:

  Wed Aug 7 @ 15:00 Eastern/13:00 Regina

  - KaonLT will go first

  - Dave and Julie can't attend then

  - Garth will be at Exclusive Reactions meeting @ Trento, will connect from

    hotel room

- Thur Aug 15 @ 15:00 Eastern/13:00 Regina

  - Dave will take notes

  - PionLT will go first