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June 26/25 PionLT/KaonLT Analysis Meeting Notes
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(Notes by GH)
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Today: KaonLT 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, Ivan Zhenchuk, Nacer Hamdi
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FIU - Pete Markowitz
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Ohio - Julie Roche
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York - Stephen Kay
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Virginia - Richard Trotta
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CUA - Tanja Horn
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Richard
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-------
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High Q2 KaonLT LT-separations
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- found a bug affecting the pion subtraction undertainty
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- uncertainty propagated correctly now
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- pion subtraction also improved a bit, some bins were over-subtracted, which
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explained some bad phi bins in ratio plots
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- made a new method of doing Rosenbluth fits
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- was hitting fit bounds before
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- earlier fits imposed a boundary condition sigL,sigT>0
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- now derived a better constrained fit using Cauchy-Schwarz inequality
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- baked the positivity constraint into the fit itself
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- model is now pushed out of unphysical local minima
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- uses Drechsel-Tiator J.Phys.G paper available at
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https://maid.kph.uni-mainz.de/JPhysG18/JPhysG18.pdf
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- uses rhoLT=|sigLT|/sqrt(sigT*sigL)<1.0
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rhoTT=|sigTT|/sigT<1.0
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- copy of Richard's derivation of relation at
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https://redmine.jlab.org/attachments/2878
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- now using much simpler functional forms for Q2=4.4
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- sigL=(p1*ft)*exp(-p2*|t|)
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sigT=p5/(|t|^p6)*exp(-p7*|t|)
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sigLT,sigTT also simpler, have no sin(theta*) terms yet
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- did 20 iterations with new forms
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- ratios much closer to 1 now, some evidence of oscillations so might
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restore the sin(theta*) in LT,TT
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- Q2,W,t,MM plots
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- MC:data disagreement worse for left SHMS than center at low epsilon
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similar is true at high epsilon
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- initial results: sigL~20%*sigT sigLT~sigTT
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- investigating other settings
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- need to adjust pion subtraction
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- Q2=3.0,W=3.14 left SHMS SIMC at both low and high epsilon has a shift in MM
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peak compared to data
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- still has to do HGC PID pt-pt systematics, currently estimates ~3.6% unc
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- mentions some difficulty running SIMC for very large #events
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- Garth: you can modify SIMC to use a random seed that you specify rather
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than the default one, in which case you can break a big SIMC job into
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smaller parts, provided eacn one uses a different random seed
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- Nacer asks for a copy of Richard's sig_unsep files, would like to check if he
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gets similar Rosenbluth fit to Richard
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- Richard's data at
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/lustre24/expphy/volatile/hallc/c-kaonlt/trottar/OUTPUT/Analysis/KaonLT/cache_transfer/kaon/Q4p4W2p74/Trial_20/
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- this is where all runs are for Q2=4.4 for the plots. Run
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2025June26_H07M55S23 (i=20) are where the plots are from. In
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2025June26_H07M55S23/xsects are the separated and unseparated cross section
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values
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- 2025June26_H07M55S23/parameters/par.pl_Q44W274.dat is my parameterization
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and 2025June26_H07M55S23/functions/Q4p4W2p74.model is my model
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Nacer
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-----
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Q2=0.5 KaonLT LT-separations
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- setting up framework
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- for Rosenbluth fit, using python curve_fit
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https://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.curve_fit.html
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- compared to GH's L/T/LT/TT values obtained with PHYSICA, gets same central
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values, hasn't compared the errors yet
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- sigL is negative for most t-bins, but no iterations have been done yet,
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this was with default Koltenuk model and ratios R~2
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- working on parameter iteration script
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Ivan
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----
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KaonLT BSA analysis
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- added dummy subtraction
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- updated t-binning based on sum of Left, Center, Right SHMS settings, not just
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Center
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- now has ~60k events/bin
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- simplified fit clearly makes more sense than full fit, which overfits the
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fluctuations in the data
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- extracted mean kinematics per t-bin
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- *NB* Garth suggests to cross-check both the mean kinematics and the yields
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per t-bin with Nacer's, in the region where they overlap
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- also looked at higher Q2 K+ BSA
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- Q2=2.1 and Q2=3.0,W=2.32 have good statistics, BSA looks fairly promising
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- Q2=4.4,5.5 statistics too poor to have much of a result
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- hasn't looked yet at Q2=3.0,W=3.14 setting
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Next Meeting
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-------------
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- Thur July 3 @ 15:30 Eastern/13:30 Regina
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- PionLT will go first
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