Kaon_LT Experiment

                 Jan 15-16/26 PionLT/KaonLT Analysis Meeting Notes

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                                (Notes by GH)

                    Today: KaonLT will be discussed first

Thursday: Present

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Regina - Garth Huber, Muhammad Junaid, Alicia Postuma, Nermin Sadoun,

   Nacer Hamdi

CUA - Sameer Jain, Tanja Horn, Chi Kin Tam

Virginia - Richard Trotta

Ohio - Julie Roche

FIU - Pete Markowitz

Chi Kin

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KaonLT High Q2 LT-sep

- diamond cut adjustments for:

  Q2=2.1 W=2.95;  Q2=3.0 W=3.14;  Q2=4.4 W=2.74;  Q2=5.5 W=3.02

  - compared data and SIMC for high, low epsilon, take the minimum overlap

    region

  - previous studies only looked at center SHMS settings, now overlaying

    left-right-center SHMS for both epsilons, and made some adjustments

  Q2=3.0, W=2.32

  - found an issue with high epsilon RIGHT setting

  - diamond is smaller than center & left SHMS, missing low W part of diamond

  - will reduce the size of the diamond for all settings at this Q2-W to

    compensate

  - Richard: this was the very first KaonLT setting taken, something may have

    been off

    - *NB* will take another look at the run kinematics to see if we can

      identify what caused this

- Q2=4.4 new iterations

  - compared with Richard's results from 11/06/25

    - Richard had sigT ~8, while CKT has ~60

    - *NB* Richard and Chi Kin will cross-check

Sameer

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KaonLT CoinTime Blocking

- corrected all rates for BeamOnTime

- had a question on whether the beam current cuts have been set correctly

  - looked at the run sheet target current, in some cases this was different

    than BCM2 value, which was then used

- showed some plots of CoinBlock vs corrected CoinRate

  - trends with rate generally looked a lot better now

  - Q2=3.0 W=3.14: SHMS Right CoinBlock are low compared to Left and Center

    - Garth: it could either be that the rate is calculated too low and the

      point is really further to the right, or that the CoinBlock is wrong and

      should really be higher

    - *NB* Tanja: SJ should check if the rate is too low, or if the cuts needed

      for the correction are off for this setting

Nacer

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KaonLT Q2=0.5 LT-sep

- tried a variety of L/T parameterizations

  - the best Data/MC ratios are found with

    sigT = p1/Q2 + |t|**p2/(Q2+p3)**2 and L=LT=TT=0

  - tried to add back a function for sigL, such as

    sigL = p4/Q2 + p5/|t|**p6

    which results in the ratios getting worse

  - also, sigT has a drop in cross section at low -t and he hasn't been able to

    find a funtion which describes this while getting a good fit at low -t

  - Junaid: what do the kinematic plot comparisons look like?

  - Garth: more important than the stability of the Data/MC ratios is the

    stability of the resulting cross sections

    - *NB* please make a spreadsheet comparing sigL,T for a model w/sigL and a

      model w/o sigL and let's see to what degree the cross sections are stable

    - if they are stable within errors, and the kinematic plots look good, then

      that's good enough.  If the cross sections are not stable, then we need

      to figure out next steps.

- K+ absorption correction

  - Junaid helped getting the Geant4 code to work

  - removed NGC, the other cuts in the script seem applicable

  - get a corretion of 4.2% at 2.5 GeV/c

  - *NB* it would be good to cross check with Vijay's correction

- using Nathan's LH2 boiling factor

  - *NB* should cross check it with what Chi Kin/Richard use

- Sameer has KaonLT Q2=0.5 runs, will look at CoinBlock for these setting

  - Nacer will communicate on cuts and other issues

Alicia

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KaonLT u-channel background subtraction

- found a work around for the weird Pythia issues at Q2=3.0 W=2.32

  - double bump in Python MM distribution

  - this setting also has worse MM resolution than the others

- previously, found that adjustments to Pythia input parameters made no

  difference

  - however, applying acceptance cuts makes the MM distribution smoother

  - plots of ssxpfp,ssypfp for MM<0.9(rho-omega) and MM>0.9(phasespace) regions

    show some interesting correlations

    - the idea would be to adjust the ssxpfp cut to get better agreement with

      MM distribution shape

    - change to ssxpfp<0.02 instead of <0.04

    - resulting Pythia MM distribution is smoother

  - Note: the previous MM upper edge issue (Data and MC had different limist) was

    traced to the diamond cut and fixed

  - *NB* Garth: to confirm that applying a different cut to Pythia MC than to

    data and other MC doesn't create new issues, we should look at the Data vs

    MC comparison of variables other than MM

    - from the MM fit of MC to data, find the MC scale factor

    - apply this scale factor to plots of other variables

    - make plots of subtracted data vs omega MC, and plots of data vs sum of

      normalized MCs

Firday: Present

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Regina - Garth Huber, Alicia Postuma, Nathan Heinrich, Nacer Hamdi,

   Nermin Sadoun, Vijay Kumar

JMU - Gabriel Niculesu, Ionana Niculescu

Glasgow - Kathleen Ramage, Rachel Montgomery

CUA - Sameer Jain, Tanja Horn, Chi Kin Tam

Virginia - Richard Trotta

FIU - Pete Markowitz

Richard

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KaonLT High Q2 LT-sep

- Data/MC plots for Q2=3.0 W=2.32 and Q2=5.5, using exactly the same parameters

  and functions as Q2=4.4

  - ratios are surprisingly close to 1

  - uncertainties now include background subtraction uncertainties, so are much

    larger in some cases

- errors look quite large for larger Q2 settings, need to reduce t-binning and

  change upper and lower t-ranges

  - Q2=4.4: need to go from 4 to 2 or 3 t-bins, also 15 to 9 phi bins

  - Q2=5.5: need to go from 2 to 1 t-bin, reduce phi bins too

- kinematic plots: Q2=4.4 HMS-delta has some disagreement in shape, the others

  are fairly reasonable

To Do:

- need to deal with the diamond cut identified by Chi Kin

- need to address Q2=4.4 cross section discrepancy between CKT and RT

Vijay

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PionLT Low Q2 systematic studies

- changing CoinTime cut by +/-10%, last week found that low epsilon sigUNS was

  much more sensitive than mid and high epsilon

- given this is sensitivity, Garth asked VK to look at this vs t

  - obtained separated cross sections for the +/-10% cut variation

  - Garth had asked to try with no iterations to model

  - Q2=0.375: sigL changed by 18%

  - *NB* Tanja: suggests to do 1-2 iterations to see if this sensitivity

    remains

- shows some fits of PKT model to Q2=0.375,0.425 data

  - model shows a turn over in sigL at lowest -t that is not exhibited by data

  - we have some discusion about this

  - more studies are clearly needed to assess the reliability of the model to

    these kinematics

Nermin

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PionLT LD2 setting up for PID studies

- created a run list of LD2 data for all 4 beam energies

- had some issues submitting iFarm runs, which has been fixed

- produced ROOT files were corruped, need to look again at production scripts

Kathleen

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PionLT setting up for data analysis

- looking at previous Heep data replay raw trees

  - using Junaid's script: singyield_heep.py for Run 10600

  - looking into why H_gtr_xptar,yptar are missing

  - will compare W vs yield for SIMC and Coin Data

Next Meetings

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- Thurs: Jan 22 @ 16:00 Eastern/15:00 Regina

  - PionLT will go first

- Fri: Jan  23 @ 11:00 Eastern/10:00 Regina

  - we will continue where we left off