Kaon_LT Experiment

                 Feb 27/25 PionLT/KaonLT Analysis Meeting Notes

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                                (Notes by GH)

                     Today: KaonLT will be discussed first

Present

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Regina - Garth Huber, Ali Usman, Alicia Postuma, Muhammad Junaid,

   Nathan Heinrich, Nacer Hamdi

FIU - Pete Markowitz

Ohio - Julie Roche

Virginia - Richard Trotta

JLab - Dave Gaskell

Alicia

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pi+n BSA revisions

- please send your comments ASAP!

- comments received so far from Dave Mack and Vijay

- minor changes will be made to one figure and the text

Simonetta Liutti comtacted GH that she is starting to work on pion GPDs and

requests data

- Alicia is helping put together a spreadsheet of sig0,L,T,LT,TT,LT' cross

  sections for exclusive pi+,pi-,pi0,K+ reactions

- Julie also received a request for pi0 data, will coordinate with Alicia

- Simonetta also requested exclusive eta data

  - Pete will make some inquiries regarding the CLAS eta data tables

Vijay

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Unfortunately, I cannot make the meeting today. I'm changing my apartment and

fully busy. However, I've decided to report my update through email.

1) I've implemented the new diamond cuts in the analysis that determined for

   the Q^2 =0.42 GeV^2.

2) I've started the changing t binning for the analysis. It's a critical to

   have similar statistics (including all settings) in all t bins.

3) I want to check the ftave equation in the SigT cross-section for this

   analysis.

Hopefully, I'll have some plot from data and MC comparisons in the next

meeting.

Richard

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KaonLT High Q2 L/T-separations

- Q2=4.4 after 10 iterations using same parameterization as last week

  - highest -t bin has oscillations in R=Data/MC but lowest -t bin looks flatter

    - GH: this indicates the parameterized t-dependence is probably different

      than the data at high -t

  - noted for some time that sigT is strongly negative for lowest -t bin

    - this has been traced to a single phi bin with tiny errors

    - if this point is removed, sigT is not so negative

    - will do some investigation of this point, maybe there's some pion

      contamination sneaking in that is driving the errors

- Q2=5.5 after 10 iterations, same parameterization

  - high epsilon has large R=Data/MC while small epsilon has small R

  - similar issue with negative sigT in lowest -t bin, will check contamination

    here as well

- Pete: Q2=4.4, 5.5 both have nearly zero sigL,T for -t~0.75, is the cross

  section really nearly zero there, seems puzzling that the cross section is so

  small there

  - Richard: not sure yet that's so believable.  Notice also that LT,TT are

    fairly large for these bins

Junaid

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PionLT Heep analysis

- GH followed Dave's idea from last week and made two new sets of offsets

  1) global fit of 9 settings from 5.5-9.9 GeV beam energy:

     dthe  0.7000   dpe  1.0000   dthp  1.8000   dpp -0.8500

     dE: -0.3000 -0.2000 -0.2000 -0.2000 -0.3778 -0.1556 -0.6000 -0.4889  0.4000

  2) fit of just 10.6 GeV setting, where the HMS and SHMS angle offsets are

     taken from (1) and only new momentum and beam offsets are fit:

     dthe  1.5000   dpe -3.2000   dthp  1.4000   dpp  1.7000   dE -1.0000

     units are 0.1% for momenta/energy, 1 mrad for angles

- Heep distribution Data:MC comparo using these offsets

  - 5.5-9.9 GeV:  PMx,PMy,W distributions overlap better

    - PMz,EM not so much improved in comparison to "no offset"

  - 10.6 GeV: PMz,E agreement is better than offsets used last week from

    5.5-10.6 global fit

- Junaid takes the pSHMS offset from the 10.6 fit and apply it also to 5.5-9.9

  GeV, keeping all of the other offsets the same

  - i.e. only pHMS will be different between 10.6 and the other beam energies

    (presumably due to effect of saturation at HMS=5.8 GeV/c) all other

    HMS,SHMS offsets the same.  The beam energy offsets remain different for

    every energy.

  - the agreement for PMz,EM is improved for all 5.5-9.9 GeV settings

  - then does an investigation of global pSHMS offsets from +1.0 to +5.0, finds

    that pSHMS offset of +4.5x0.1% gives noticeably better agreement for PMz,EM

    everywhere

    - the agreement between Data and MC distributions is now quite good

  - Dave: puzzling that the Heepcheck analysis didn't give the correct pSHMS offset

    - Garth: the offset fitting program predicts data-MC residuals for the

      obtained offsets

      - the observed residuals are much worse than predicted, particularly for

        PMz,EM

      - only reason can think of is that the Heepcheck program uses only the

        centroids in its analysis, not the full data distribution

      - looked over the Heepcheck program, everything looks correct in its

        evaluation of the kinematic derivatives

- Junaid will apply these offsets to the physics data

  - will need to recheck the 10.6 setting after new HMS delta offset for 5.8

    GeV/c setting is received, but hopefully that effect is small

Nathan

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- no report, has been sick most of the week

Nacer

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KaonLT Q2=0.5 analysis

- new diamond cut, checking vs data for all SHMS settings at low and high

  epsilon

  - trying to find a cut that works for both Lambda and Sigma final states

  - plot W-Q2 after all cuts, including MM, dummy subtraction, etc

- cut looks very nice, will move next to t-binning

  - for Lambda, will try 12 phi-bins, 6 t-bins

  - Richard: tried to have >1000 events/t-bin, summed over both SHMS settings

    at low epsilon, statistics were higher at high epsilon

  - Ali: Sigma stats are much lower than Lambda, you will need fewer t-bins for

    Sigma

Next Meeting

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- Thur Mar 6 @ 15:30 Eastern/14:30 Regina

  - PionLT will go first

- NOTE: on Mar 9 USA moves to DST, so we will need to move to 16:30

  Eastern/14:30 Regina for the period March 13-April 10

  - after that, we can return to 15:30 Eastern for the convenience of our USA

    colleagues