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July 3/25 PionLT/KaonLT Analysis Meeting Notes
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----------------------------------------------
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(Notes by GH)
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Today: PionLT will be discussed first
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Please remember to post your slides at:
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https://redmine.jlab.org/projects/kltexp/wiki/Kaon_LT_Meetings
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Present
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-------
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Regina - Garth Huber, Nathan Heinrich, Ivan Zhenchuk, Muhammad Junaid,
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Nacer Hamdi
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JLab - Dave Gaskell
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Virginia - Richard Trotta
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CUA - Tanja Horn
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FIU - Pete Markowitz
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Junaid
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------
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Q2=3.85, W=2.62 LT-sep
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- now using functional forms from Tanja's thesis Eqn 5.9
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- initial parameters are same as Table 5.1 Final Values
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- ratios using this parameterization are not surprisingly worse than with the
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Bosted global parameterization
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- high eps: R~0.7 at low -t to R~0.1 at high -t
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- low eps: R~1.0 at low -t to R~0.2 at high -t
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- we expect these ratios to converge rapidly to near 1 after a few
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iterations, the important thing now is the functional form that is tried
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- still two scripts to write for LT-separations:
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- SIMC weight recalculation script
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- functional fits to LT-separated cross sections
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- also still doing checks on correct error calculation method
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Nathan
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------
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PionLT deadtime investigations
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- had a conversation with Dave last week about the unexpected time shifts that
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need to be corrected
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- has all scripts working now to check if there is a difference if TCOIN.param
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is called, or ONLINE params
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- can replicate timing shifts between:
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- explicit call TCOIN.param and implicit call standard.database
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- explicit call ONLINE param and implicit call standard.database
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- this means the implicit one is overwriting the explicit one
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- the weird timing shifts must be coming from standard.database
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- further to this, Nathan went through with Dave and identified some timing cut
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parameters that are too tight
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- if no good time is found within the window, it might be grabbing a garbage
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time instead
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Nacer
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-----
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KaonLT Q2=0.50 Lt-sep
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- also moved to Tanja's thesis parameterization
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- everything is the same as Junaid, except that mK substitutes for mpi in TT
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denominator
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- no plots to show yet, but ratios are generally similar to what Junaid
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showed, i.e. a decreasing ratio with -t while the Koltenuk model had flat
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ratios near 2
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- discussion about the calculation of errors
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- MINUIT is the "gold standard" that all errors should be compared to
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- Nacer is using curve_fit in python
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https://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.curve_fit.html
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- Dave has confirmed on his own that using absolute_sigma=true in Python
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gives errors very similar to MINUIT
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- example call used by Nacer:
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curve_fit(fit_func, phi_all_fit, xsec_all_fit, sigma=err_all_fit, absolute_sigma
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=True, p0=[0.04, 0.16, 0.00, -0.01])
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- Garth's quick script using PHYSICA fit
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- Dave agrees that "E2" error is the one to use, agrees well with MINUIT
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Ivan
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----
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KaonLT BSA analysis
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- Q2=3.0, W=3.14 K+ sample that was missed last week
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- some phi bins are ~2 sigma away from zero, BSA~0.1, a bit bigger than
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the other K+ Q2 settings, of course statistics are better too
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- only one bin covering full t-range
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- Q2=0.5 pi+ 5 t-bins
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- statistics are fairly good
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- BSA is somewhat larger for highest t-bin [0.067-0.11]
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- Nacer: some of the BSA plots are not left-right symmetric about phi=0
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- Dave: this is likely statistical fluctuations, not new physics
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- *NB* Garth: Ivan should take a look at pi+n event selection, PID systematic
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uncertainties
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Richard
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-------
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KaonLT high Q2 LT-sep
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- ran new functional forms for all settings
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- Good News! the new functional forms give reasonable results for ALL
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kinematics
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- adjusting pion subtraction scaling for bad t-phi bins
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- previously was using a common background subtraction factor for all
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settings
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- now applying a separate factor for each t-phi bin, as Nacer does
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- this has a significant impact for some bins, as the factor varies from
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~0.85 to ~0.2, depending on the bin
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- i.e. the pion background was significantly over-subtracted for some bins
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previously
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- the factor is determined by equalizing the integrals in the 0.88<Mk<0.92
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region between K+ spectrum and clean pion spectrum
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- hoping this will help the bins for which sig_uns is higher at low epsilon
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than high epsilon
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- *NB* Garth: now that there is a common parameterization for all settings, it
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would be a good idea to make a plot of each fit parameter vs kinematics
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- see his LT-sep slides for an example
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- want to see if the parameter varies in some gradual fashion with
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kinematics, or not
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- this can give clues on whether there is a significant ingredient missing
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in the parameterization, or not
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Next Meeting
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-------------
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- Thur July 10 @ 15:30 Eastern/13:30 Regina
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- KaonLT will go first
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