Kaon_LT Experiment

                 Mar 6/25 PionLT/KaonLT Analysis Meeting Notes

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                                (Notes by GH)

                     Today: PionLT will be discussed first

Present

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

FIU - Pete Markowitz

JLab - Dave Gaskell

Ohio - Julie Roche

Virginia - Richard Trotta

CSULA - Konrad Aniol

Junaid

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PionLT Heep Studies

- using global offsets presented last week

- Data/MC ratios using Nathan's LH2 boiling factor

  - MM cut applied to exclude pi0, same cut value for all settings

  - R=0.89-1.020, average value ~0.95, which is MUCH better than earlier

    analysis

  - will have to apply Alicia's proton correction (~5%), and Nathan's final

    rate corrections (undetermined but will be small).  With these applied, the

    ratios will be quite close to 1

  - Dave: intrigued by varying ratio for the three 6.395 GeV settings,

      variation from mean is about +/-0.05, which is much larger than the

      statistical error

    - we look at the setting kinematics, no obvious trend with anything

    - pHMS is not in saturation region

  - Dave: one Heep setting has evidence of a shift in HMS-delta between Data

    and MC (P_HMS=3.7 MeV, theta=31.6)

    - this might indicate that the swap in calculating offsets between

      theta_cent and P_cent is not quite right

    - we look at another setting to see if there's a consistent trend

      P_HMS=3.8 MeV, theta=29.7 setting showed no HMS-delta shift even though

      the setting kinematics are very similar

    - Garth: from everything he's seen, there appears to be a certain amount of

      non-reproducibility from one setting to another.  For example, when

      returning the spectrometer magnets to a previous field, the currents

      usually differ by 1A or so from the previous value.  It might be

      something along these lines

    - Dave: the beam energies are different between these two settings, and

      those are independent energy measurements, so that is a more likely

      source

  - Julie: we should take a look at the Heep setting with R=0.88

    - this shows no evidence of a shift, just a normalization difference

      - JM: will check if any bad runs were included by mistake

  - some discussion whether any further optimization is needed of Heep cuts

    - Dave: the difference between data and MC left of the W peak is due to

      mismodeling of resolution in SIMC.  It's not experimental background and

      these events should not be removed as they're valid events

Next steps:

- started working on Q2=3.85, W=2.62 physics setting with 2 epsilon points

  - param files updated and pushed to GitHub

Alicia

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Discussion about BSA PLB updates

- already started entering the article metadata in the journal server

- created a Mendeley Data Repository for spreadsheets of numbers and other info

  that will be cited from the paper

- planning to submit no later than Monday

Nacer

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KaonLT Q2=0.5 analysis

- working on t-binning, some jobs still running so no plots to show yet

- some discussion about binning strategy

  - Richard: absolute minimum of 1000 events per t-bin, 2000 is better

  - Garth: it would be great if we could get 5 t-bins, no need for many more

    than this, it would be better to instead have more phi bins

  - will start with 10 phi bins

Richard

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KaonLT Q2=4.4, W=2.74 LT-separation

- did some checks to resolve the sigT<0 for lowest t-bin

  - found that this bin had significant pion contamination

  - raised lower limit of bin from 0.35 to 0.40 to remove pion background

  - as a result, sigT is closer to zero now for this bin

  - upper limit of this bin was unchanged at 0.85, will raise it higher as well

    so the bin has more statistics, and then will do some iterations

- Garth: a bit surprised that the fit (red) curves for LT, TT don't go to zero

  as -t -> -tmin even though the functional form has sin(theta*) dependence

  - Richard: over the t-bins, theta*=22-31deg

  - Garth compares to 6 GeV data, where theta*=2-13deg

  - maybe it's a kinematic effect at the higher energy, but it's a bit

    surprising that theta* is so large for the lowest t-bin

    - Richard will check

Next Meeting

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- Thur Mar 13 @ 16:30 Eastern/14:30 Regina

  - KaonLT 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