Kaon_LT Experiment

                 Nov 13-14/25 PionLT/KaonLT Analysis Meeting Notes

                 -------------------------------------------------

                               (Notes by RLT & 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

----------------

Regina - Nathan Heinrich, Nacer Hamdi, Alicia Postuma, Nermin Sadoun

Virginia - Richard Trotta

CUA - Tanja Horn, Chi Kin Tam

JLab - Dave Gaskell

Richard

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KaonLT Q2=3.0, W=2.32 LT-sep

- Using the same functional forms as Q2=4.4, W=32.74

- Ratios look fairly flat with little structure. There are 2-3 bins that dip

  and need investigation

  - The distributions look okay overall, but more iterations will be needed

    (currently only 3). The delta distributions, in particular, are a bit off.

- New outline for analysis going forward

  - Finish and refine Q2=3.0/W=2.32, Q2=4.4/W=2.74,Q2=5.5/W=2.95 (scaling

    settings)

  - Then work on the fit algorithm paper and studies (fitting Fpi1/2, low Q2

    Pion-KaonLT, etc.  data)

  - Chi Kin to finish up Q2=3.0/W=3.14  

    - Then finish cross section systematics checks on these settings 

  - Once Sameer is finished up with cointime blocking correction, a final full

    replay will be done

    - With the full replay finished, Richard will check and finalize

      systematics

Chi Kin

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KaonLT Q2=3.0, W=3.14 analysis

- Rebinning in t and adjusting t-range 

  - Showed average t per bin vs t bin center

- Same functional form as Richard

  - Initial parameters determined from distributions

- 0th iteration lookd reasonable with high > low eps in unseparated cross

  sections

   - Shape a bit odd for sigT and just one iteration dramatically changes the

     cross sections and ratios look much worse

   - Unphysical parameters (local minima likely) result in a negative total

     cross section

   - Will be using Richard's fit algorithm for a better set of initial

     parameters

   - Nathan: given the plots, how can the total cross section be negative?

     - Likely a bug in the code because the 0th iteration overall looks very

       reasonable (unspe/ratios/sep/kin/etc).

     - *NB* GH: it's important to plot cross sections over the full kinematic

       range of the data, not just the range spanned by the nominal t-values of

       the bins.  Maybe the parameterization is doing something weird on the

       edge of the distribution?

 - Discussion if Kin should shift data and simc MM to lambda mass of 1.115

   or just shift MM data to simc.

   - Tanja: simc is "truth" so data should shift to it

Alicia

------

pi+n BSA PLB paper

- Has been accepted, there are a few, brief comments from one referee

  - There's some confusion about exact coverage and correlation of kinematics

    for different settings

    - Garth suggested adding a t-phi plot but space is limited.

      - Tanja suggested a reference to previous LT papers

      - what Garth actually meant was to put the plot in the supplemental

        material, not the paper

  - Referee unsure why bin widths are indicated by standard deviation instead

    of just edge of each bin

    - Alicia and Garth have showed to our group the different methods so just

       explaining to referee is probably fine

  - Radiation corrections are still not discussed in text

    - Alicia is expanding some of the text

  - Fix Q2/x but correlated with t

    - Leave as it

  - Proper citations

    - PLB Website issues

  - Figure 7: GK model has shows such strong dependence on Q2

    - Alicia: scaling of denominator to show dependence, but is that worth

      doing?

      - Tanja: Probably fine as is, not a theory paper

  - Various minor edits to wording, etc.

    - No comments, looks good

- expect to submit final version for publication in a few days

Nacer

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KaonLT Q2=0.5 LT-sep

- Verbal: Trying to improve ratios with continued adjustments

Nathan

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PionLT finishing up CoinLumi studies

- Showed coin yield vs current

  - Using Dave's previous suggestion, fit to constant 

  - No chi2 yet from Nathan, Dave says that should be first step. 

    - If good chi2 then statistically consistent with a constant so no systematic

      correction.

    - If bad, then need to think about systematic. Possibly, amplify error bar

      until good chi2 achieved then quantify that amplification.

  - Friday update: did a combined fit using error-weighted average, get flat vs

    rate within ~1 sigma

    - Note added after meeting: Nathan finds that adding 0.72% to the error bars

      results in a reduced Chi-square of 1.  Dave and Garth agree the adjusted

      plots look good  

- Coinblock corr vs coin rate

  - A bit of a spread, but trends per setting are consistent

    - Two settings (Nathan's categorization, exclusive lumi 3 vs 4/5) should be

      the same but aren't. Someone may have adjusted the electronics, but no

      log entry on this.

      - Garth has no recollection of any such electronics changes during the run

      - One other point is off trend, but error bars are large so likely low

       statistics run.

Friday: Present

---------------

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

   Vijay Kumar, Nacer Hamdi

CSULA - Konrad Aniol

FIU - Pete Markowitz

Virginia - Richard Trotta

CUA - Tanja Horn, Chi Kin Tam, Sameer Jain

JMU - Gabriel Niculescu

York - Stephen Kay

Ohio - Julie Roche

Vijay

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New Low Q2 PionLT results

- CoinTime blocking and pion absorption corrections now included for both Q2

  - pion absoprtion correction: 2.02%+/-0.045% (see June 5/25 slides),

    correction is applied by dividing by 0.979

- Q2=0.375 results

  - mid epsilon Data/MC ratios: 0.9-1.2 with some scatter

  - Rosenbluth fit of sig_uns has smaller chi-square than before

  - 5-10 iterations done after corrections applied

- Q2=0.425 results

  - mid epsilon Data/MC ratios: some larger ratios at edges of phi-dist, 0 and

    360 deg

  - TT trends to 0 at -t=0.01, LT is constant (not zero) at -t=0.01

  - sigL vs t is less smooth than at Q2=0.375, big jump for lowest t-bin

- next steps:

  - working on systematic uncertainties

  - preparing kinematics and acceptance plots for next week

  - will send tar files of results to spokespersons

Sameer

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KaonLT CoinTime blocking at 6.2, 8.2, 10.6 GeV beam energies

- still need ROOT files for Q2=4.4 (10.6 GeV)

- no error bars yet

- blocking corr @ Q2=3.0, W=3.14

  - get 3 parallel bands vs Rate with values of 0.92, 0.93, 0.94

  - *NB* Garth: this seems weird, is it a round off issue when calculating the

    ratio?

- blocking corr @ Q2=5.5, W=3.02

  - high epsilon shows a band at 0.78, with rest at 0.85

  - *NB* Nathan: concerned that the timing window is not set correctly for

    these

    - maybe standard.database is not pointing to the correct file for these

     runs?

  - low epsilon shows some corrections of 0.4 at low rate

    - *NB* Nathan: this needs more investigation, compare the shape of timing

      plots for good and bad runs

      - if shapes are similar, the correction can't be very different

      - if shapes are different, then need to confirm the applied cuts are

        correct

  - *NB* Garth: please show sufficient information next time that we can help

    you determine what might be wrong

Junaid

------

PionLT Q2=3.85, W=2.62 LT-sep

- working on pion absorption correction following Alicia's instructions

  - turned on NGC in Geant4 code

  - set Aerogel tray to n=1.011 thickness

  - ran 100k events

  - applied default cuts should be okay for this configuration

  - resulting correction is similar to Vijay's but there are more secondary

    particles produced due to the higher momentum

  - *NB* Garth: please give more info next time on how the secondaries are

    handled in your Geant4 analysis

- all other corrections are applied to the data

Next Week Meetings

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- Thurs: Nov 20 @ 16:00 Eastern/15:00 Regina

  - PionLT will go first

- Fri: Nov 21 @ 11:00 Eastern/10:00 Regina

  - we will continue where we left off