Kaon_LT Experiment

                 Sep 12/25 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, Nathan Heinrich, Nacer Hamdi, Muhammad Junaid,

   Alicia Postuma, Nermin Sadoun

FIU - Pete Markowitz

CUA - Tanja Horn, Chi Kin Tam, BC Munoz, Sameer Jain

York - Stephen Kay

Ohio - Julie Roche

JMU - Ioana Niculescu

JLab - Dave Gaskell

Nacer

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KaonLT Q2=0.5 LT-separations

- replicated sig_factorized_2007 model in physics_iterate.f

  - this model uses different cross-section units than the usual

    d2sigma/dt-dphi so a different Jacobian was needed

  - will use sig_factorized_2007 model for first iterations, which are still in

    progress

Alicia

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pi+n BSA paper modifications

- completed radiative correction systematic requested by referee

  - Asymmetries for radcor=ON/OFF are nearly identical

    - max discrepancy is 0.002 (or 0.35% of Asymmetry) for Q2=3.0, W=3.14

    - still running other settings, max discrepancy so far is 0.003 or 0.6% of

      Asymmetry

- received reconstructed VR Regge model from CKY, now all models in Fig 6 use

  exact kinematics as data

  - this gives much better agreement with data at low -t

  - VR model is now also included in Fig 7

  - VR model gives good agreement with data

  - now both Regge-based models agree better with data than GPD model, which

    also addresses a question by referees

  - will try to smooth the theory curves in Fig 6, probably kinks are due to

    varying kinematics of data, the kinks are most noticeable in GPD model

- planning to circulate both modified paper and referee comments early next

  week

Ioana

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KaonLT Lambda/Sigma/Lambda* ratios

- looking at KaonLT Heepcheck analysis

  - having difficulty locating the offsets Richard used, found some

    discrepancies among GitHub files

  - *NB* both Alicia and Chi Kin will send what they're using

Chi Kin

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KaonLT high Q2 analysis

- lots of broken files in cache, replayed all 10 settings in Q2=3.0 W=3.14 and

  Q2=2.1, W=2.95 settings

  - for runs which were good before, the new file size is somewhat larger than

    Richard's (e.g. Run 5013: new=847MB old=713MB)

    - Ioana: also noticed some missing files in cache

    - Stephen: some farm jobs had failed and output was not properly closed

    - MM is identical

    - *NB* Garth: please also check #events between old and new versions

  - Nathan, Junaid: believe the correct GitHub to use is MASTER, not

    LTSep_Analysis_2022, which does not include most recent updates

    *NB* please check with Richard on this

- Diamond cuts rechecked, low epsilon nicely centered in big epsilon diamond

  - *NB* Garth: please also compare the low epsilon Data and SIMC diamonds, if

    there is a shift between Data and MC, it's important to take the SMALLER of

    the low epsilon diamonds

- MM-shift fits

  - fitting Lambda peak w/ Gaussian, same shift applied also to pion

    leakthrough data

  - see a small pi+n MM shape difference between pion leakthrough and pure pion

    samples

    - Ioana: leakthrough and clean pi+n samples have slightly different delta

      distributions, which accounts for the shape difference

- SIMC negative weights

  - using what believes to be Richard's latest parameters

  - Left SHMS settings have negative weight, which is surprising, still

    checking with Richard on whether using the correct parameters

  - found that the weights are negative in a specific region of t-phi

    - for now, just reduce LT function parameter causing this, to give positive

      weight

  - also found that TT gives negative weight at high -t, outside expt

    acceptance

    - Garth: in this region the TT model is unphysical, but since it's outside

      the expt acceptance, it will have no impact upon the results

Junaid

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PionLT Q2=3.85 LT-separations

- making changes to LT-sep functions due to problems identified last week with

  T,TT

  - changed T=(p1/Q2)*exp(p2*Q2)*exp(p3/|t|)

  - TT also changed, first part of function is (p14/Q2)*exp(p15*|t|)+polynomial

  - with initial parameters (0th iteration) high epsilon Data/MC ratios are

    low

  - 1st iteration: high epsilon Data/MC ratios near 1 but with significant

    phi-dependence similar to low epsilon

  - 2nd iteration: high epsilon ratio osc got stronger, ratios still centered

    near 1

- some parameters in L,LT,Tt functions are held fixed during iterations

  - *NB* Garth: with the fixed params, LT,TT have no freedom in fitting Q2=dep,

    suggest to freeze one of the t-dep params and unfreeze the Q2-dep param

  - Nacer: suggests to fix exponential param to a small value and allow the

    polynomial term to float in fit

  - *NB* Garth: also please extend the model curves to end of t-range of data,

    and add curve of previous model to plots, so you can more easily see how

    the model varies between iterations

Nathan

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PionLT Coin Blocking Studies

- plot integration problems from last week fixed, calculating

  OUTSIDE-CUTS/FULL-RANGE ratio per setting, using CUT=30-130ns RawCoinTime

  range

  - Plots of correction vs Rate go from near 1 at low rate to ~0.95 at high

    rate, lots of variation between settings at same rate

    - SHMS Rate has the tightest correlation between settings

  - fitting with an exponential to get the time constant

    - get 53-83ns vs SHMS rate, depending on setting

    - Dave: this time constant is an effective dead time

- implemented the correction into CoinLumi yields

  - *NB* something is wrong, curves vs. Current are steeper instead of

    shallower, need to recheck

- changed RawCoinTime cut to 30-100ns from 30-130ns based on narrower

  distribution seen for 1 run

  - this gives a larger correction, up to 10%, still working on it

  - Garth: it's important to confirm that the correction is ~1 at very low

    rate, where there would be no blocking

- Dave: what were the HMS+SHMS gate widths?

  - Dave finds https://logbooks.jlab.org/entry/3892668

    which has HMS=30ns and SHMS=50ns widths

  - *NB* Nathan needs to look more carefully at logbook and check for other

    entries

  - Garth: the obtained time constant and gate widths should be approximately

    consitent with each other, as they're effectively measuring the same thing

- also investigating effect of including GoodTrack and GoodStartTDC cuts in

  this analysis, Mark Jones had suggested using both cuts

  - if the GoodTrack cut is removed, the correction is up to 20%

  - Dave: there will be additional inefficiencies caused by these cuts

    - as long as they are treated separately, so that this study is

      uncorrelated from them, it should be okay to keep the cuts

  Next Meeting

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- Fri Sept 19 @ 11:00 Eastern/9:00 Regina

  - PionLT will go first

** NOTE THE NEW TIME **

- this time will be in effect until USA daylight savings time change, after

  which it will switch to 10:30 Eastern/9:30 Regina