Kaon_LT Experiment

                 Oct 10/24 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, Alicia Postuma, Nathan Heinrich, Muhammad Junaid,

   Vijay Kumar, Nacer Hamdi, Argha Das

CUA - Casey Morean, Tanja Horn

JLab - Dave Gaskell

Virginia - Richard Trotta

Ohio - Julie Roche

FIU - Pete Markowitz

Vijay

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Finalized PhaseSpace Volume Cut Systematic Study

- varied delta_HMS cut by -10%, as discussed last week

- calculate R=Y_DATA/Y_MC for each (t,phi) bin, then do error-weighted average

  of R of 16 phi-bins, for each of 7 t-bins

- R changes 1-5% from low to high -t bin

- quadrature sum of delta(-), xptar(+-), yptar(+-) gives 1.2% to 6.5% from low

  to high -t bin

- Tanja: have you done any checks yet on whether the new replay is the same as

  this or different?  It would be good to not waste time by having to repeat

  the study if the new replay is different?

  - files directly from hcana replay were lost, files after python analysis

    were correctly archived

  - replay of Q2=0.42 should happen next week, first have to modify replay

    scripts for ALMA9 then submit

  - will replay Q2=0.38 at same time, still have to check that results are

    unchanged

- Garth: it will be important to archive the code used to generate the results,

  including the replay scripts

Alicia

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Response to Referees on BSA PRL draft

- key authors promised to give feedback on the response letter, as well as the

  manuscript, no later than Monday

Nacer

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KaonLT Heep singles analysis

- ran singles replay after lots of help from Junaid

- still debugging results

Nathan

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PionLT Luminosity scans (COIN SIDIS and exclusive pi+)

- initial results shown, but still have to refine cuts and implement random

  subtraction

  - remove goodscinhit==0 cut

  - remove hgc>1.5npe cut, as protons giving knock-on electron Cherenkov signal

    will give a rate dependence

  - remove beta-cut, as we discussed a few weeks ago

- issues seen with CPULT

  - Exclusive: number OK but errors weird

  - SIDIS: CPULT up to 300%, so wrong variable somehow used in calculation

- SIDIS#1 COIN yields, LH2 12200-12216

  - anti-boiling LH2 seen for scaler, no-track and track analyses, but should

    look better after randoms subtracted

  - SIDIS#2, LH2 anti-boiling is less

- Excl#1,3 LH2 14601-14606, 15816-15846

  - no-track is flat, will go down after random subtraction

  - track has 20% boiling, which is larger than SIDIS (~10%)

- Excl#4,5 16220-16242

  - similar to Excl#1,3

Junaid

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Hodo-3/4 efficiencies

- Mark Jones made significant changes to hcana code which seem to have fixed

  the issue, now getting ~99% efficiency for both Heep and Physics data

- recompiled hcana for both PionLT and KaonLT, so everyone has access to the

  changes now

- still investigating exactly what Mark changed, but as a summary:

  - modified module for event selection used to calc Hodo-3/4 Eff

    - need to add parameters to "phodo_cut.param" file

    - essentially, events w/HMS singles need to be removed when calculating

      SHMS efficiencies

  - added module to check missing track positions, fTrack_Miss_Xpos, Ypos

  - added goodstarttime cut

- with the new efficiencies, Heep ratios are 0.95-1.013, excluding one outlier

  setting with R=0.85

  - Richard's boiling correction is applied, awaiting result of Nathan's

    analysis

New HMS matrix elements

- Christine will release 5.6 GeV/C ME in ~1 week

  - 5.9 GeV/c is half done so far, should also not be long

  - 4.9 GeV/c is planned to be analyzed, apparently some evidence of saturation

    already there

  - 6.8 GeV/c, unsure of ME fitting status

PionLT pi+ PID studies in progress

- looking at 3 settings, one of which has Theta_SHMS=5.50deg

- iterating over RF, CoinTime, Aerogel, HGC cuts to understand particle

  distributions and efficiencies

Richard

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KaonLT L/T-separations

- varying exponent "n" in 1/(W^2-mp^2)^n factor in cross section

  parameterizations

  - varies with increasing W, from n=3.40 at W=2.32 to n=2.25 at W=3.14

- also trying two different TT-parameterizations

  sigTT=(p13*Q^2 * exp(-Q^2))*ft*sin^2(theta)

  sigTT=(-p13*|t|+p14)*|t|^(Q^2/p15)-p16*Q^2

  - more complicated expression generally does better, but there are few t-bins

    so it is difficult to constrain so many parameters

  - Garth: suggests to figure out which parts of the complicated expression are

    more important, and simplify the expression to just that part

    - also can play the strategy of fixing some parameters and releasing others

      in the fit, and then fixing them and releasing the others.  The downside

      is that it takes many more iterations to converge, but it helps avoid the

      issue of too many degrees of freedom in the fit

- Ratios after 5 iterations are generally near 1 now

  - Q2=4.4: Ratio drops linearly with -t

  - sig_UNS is consistently higher at high epsilon than at low epsilon now,

    which is very good news

  - will arrange a meeting with Garth and Tanja next week to discuss the ratios

    in more detail

Next Meeting

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- Thur Oct 17 @ 16:30 Eastern/14:30 Regina

  - PionLT will go first