Mar 14/24 PionLT/KaonLT Analysis Meeting Notes ---------------------------------------------- (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 ------- Regina - Garth Huber, Nacer Hamdi, Ali Usman, Muhammad Junaid, Nathan Heinrich, Vijay Kumar, Alicia Postuma CUA - Richard Trotta York - Stephen Kay CSULA - Konrad Aniol JLab - Dave Gaskell Ali --- MM shape study for DeltaPi BSA - reran MC's with new resolution parameter - starting on settings with lower P_HMS, where delta correction is not needed - shows Q2=3.0, W=3.14, high stats setting, positive helicity - initial fit of MCs to data - new 10 MeV/bin instead of previous 4 MeV/bin (lower statistical errors/bin) - with new MM binning, it is now more clear that strength of DeltaPi peak is underestimated for some phi-bins - since SIDIS and rho bkds are so similar, using a fixed ratio of 90% SIDIS/10% rho for now - cyan=sum of bkds, pi+n tail+SIDIS+rho - optimistic that 2 t-bins can eventually be used for this setting (data shown is over full t-range) - GH: since they are so similar, why don't you try fitting just one of rho or SIDIS to see which one is better, and just use that one? - DG: this would be an unphysical choice, but it probably makes no difference to your analysis - Nacer: why are you fitting each phi bin separately? - we have confidence that SIMC can properly describe the shapes for the different processes, but not their amplitudes, so we need to fit each phi bin separately Alicia ------ MM cut study after resolution correction implemented in SIMC - Dave suggested calculating Data/SIMC ratio for different MM cut values - UofR group meeting also suggested to compare w/ w/o HGC cut - HGC gets rid of KLambda leakthrough but not the shape of the region between pi+n and KLambda - ratios do not in general have a plateau vs MM cut - Q2=3, W=3.14 data shown - t-bins 1,2 show a decrease in ratio vs MM - t-bin 3 shows a plateau - t-bins 4-6 show an increase vs MM - behavior is similar for Q2=4.5, 5.5 - since the ratio is not flat, will instead try placing MM cut in region where expt yield is flat - Q2=5.5, flat region is MM=0.99-1.03, so will try MM cuts 1.01+/-0.02 - Q2=4.4, Q2=3.0 W=3.14, flat region looks similar, so same MM cut - GH: can't think of anything better to try, given the situation - Dave: have you looked at BSA vs MM cut? - a preliminary study was done last year, the final study will be done with these MM cuts - Dave: if SIMC handles the radiative corrections properly, any cut below 2pi threshold should give the same answer - GH: not sure about this, the pion scattering in the collimator also populates this region, in Fpi-1,2 we had to use a cut well below 2pi threshold to avoid being too sensitive to this region - Dave: there is no SHMS collimator routine in SIMC - GH: wasn't aware of no routine was included at all. *TASK for GH:* find the HMS collimator code used in Fpi-2 analysis, and get instructions on how to modify it for SHMS collimator geometry - Nacer: can an RF cut be applied to help clean up this MM region? - no, only a small subset of 10.6 GeV data has the RF information available, unfortunately HMS Delta-correction - P_HMS=6.59, Q2=3, W=2.32 data - hcana uncorrected MMpi vs hsxpfp shows line with tilt on top half - using reconstructed MMpi script to determine correction - applying if hsxpfp>0: hsdelta+=3.0*hsxpfp - resulting MM distribution is narrowed - P_HMS=5.292, Q2=2.1, W=2.95 data - hcana uncorrected MMpi vs hsxpfp shows line with tilt on bottom half - correction: if hsxpfp<0: hsdelta-=4.0*hsxpfp - having difficulty implementing this correction in hcana - recompiling hcana on iFarm gives complaint about missing PODD variables - Stephen: please *send* the PODD error and he will look at his notes to see if he can fix - Nathan: thinks it might be better to implement correction in the kinematics file CKY Regge model - received LT' predictions from BG Yu for the BSA paper Richard ------- Subtracting pion leakthrough - last week's results had HGC hole cut inverted, taking only events in the hole - now the pi+ dist comes all the way across the MM acceptance - Q2=2.1 setting, high epsilon - pi+ subtraction does not clean up region left of KLambda peak - planning to re-optimize PID cuts after graduation Unsep and Separated Q2=3.0, W=2.32 xsect - shows ratios vs phi,t at high, low epsilon - looking at what's responsible for Data/SIMC ratios being much larger at high eps than low eps - trying various initial values of model parameters sigL=g(W)*(p1+p2*logQ2)exp(p3+p4*logQ2)*(-t+0.2) -- changed last part to just -t to get better t-dependence sigT=g(W)*p5/(1+p6*Q2) - Dave: maybe remove the Q2-dependence and only have a simple t-dependence - Dave: the *real issue*, however, is that if you have sigL<0 from the beginning, there's a problem with the data itself, not the iteration - GH: exactly what MM region is integrated for these yields? - MM cut is applied after pi-subtraction - GH: if we can't clean up the region left of KLambda with cuts or pion subtraction, then we will have to consider fitting a polynomial and subtracting it - Dave: yes, we will need to sort this out - Richard shows MM plots for same setting at high and low epsilon - RF cut can be used only at low epsilon, region left of KLambda is noticeably cleaner than high epsilon - GH notices that pion subtraction peak is much narrower than the pi+n MM leakthrough peak - Ali's pion sample was analyzed as if pions, not K, hence the peak is narrow - normalizing to the height of the pi+n peak will result in too little pion leakthrough being subtracted, as the integrals won't match - *Ali* will give Richard his cuts and RT will make a branch of his analysis for the pion subtraction Vijay ----- PionLT low Q2 lt-analysis - found bug in script, error bars vs phi now more reasonable - shows results after 1 iteration for Q2=0.38, all 3 epsilons - some discussion about phi-dependence of lowest t-bin - the low epsilon setting seems to have a different phi-dependence than mid and high eps, which is weird - Dave: this could indicate a residual offset issue, lowest t-bin is always more sensitive to the offsets - Vijay will investigate further - t-bins 2-7 have more consistent phi-dependence at low, mid, high epsilon - 8th t-bin has poor statistics, might have to be removed from analysis - shows separated cross sections after 1st iteration, and model fits for iteration #2 - t-bins 1,8 look like outliers for sigT,L after iteration #1 - if only t-bins 2-7 included in fit, things are more consistent - will have to see what this looks like after more study Nacer ----- KaonLT low Q2 event selection - won't show any plots, since the meeting is getting long - tweaking some cuts, changing the RF windows - RF cut is very effective, needs fine tuning - GH: since the RF cut is so effective, you can probably get by with a combination of slightly looser PID cuts, to avoid cut-dependence to the result Nathan ------ Setting up PionLT Luminosity analysis - in contact with Dave Mack regarding BCM calibrations - DM did our first calibs from 2021 run, NH will follow up with him on run#'s - Dave: if you can generate ROOT trees for him to analyze, it would be even better Weird hcana issue - hcana suddenly did not know what replay variables were - spent a day debugging - restored things, but no idea what happened, as could not find any difference from how things were set up before Going through Richard's python scripts and finding what's missing - will plan on meeting RT in early April, after his defense Junaid ------ Setting up PionLT Heep study - had some issues with lt-sep package - merged cut files for 2021,22 - added ngcer - updated RF time offsets PID cuts - HMS cal-etot-track-norm>0.7 - HMS cer NPE>1.5 - CoinTime, extremely clean, practically no randoms - should be able to just place a cut around prompt peak, no random subtraction Next Meeting ------------ - Thur Mar 21 @ 15:00 Eastern/13:00 Regina - PionLT will go first