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Comparison of the p + p - g signal selection with past results. C. Di Donato, M. Jacewicz. Signal/Background. X-section [ b]: 2.04 10 -3 9.87 10 -3 0.30 10 -3 0. 46 0.14 10 -3. Reaction: 0 e e 0
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Comparison of the p+p-g signal selection with past results C. Di Donato, M. Jacewicz
Signal/Background X-section [b]: 2.04 10-3 9.87 10-3 0.30 10-3 0. 46 0.14 10-3 Reaction: 0 ee 0 ee0 • Most frequent charged decays: • BR() = (22.73±0.28) 10-2 • BR(0) = (4.60±0.16) 10-2 • BR(ee) = (6.8±0. 8) 10-3
New VS Old RAD Stream 2 pnc 1 charged vertex rxy<4cm & |z|<8cm 2 tracks balanced charge Kinematic fit: quadrimomentum conservation with 2 clusters compatible with photon hypothesys Cut on M(recoil) to reject +-0 RAD + RPI + KPM At least 2pnc one of them with Eg>250MeV Two tracks with balanced charge and closest to IP using info at pca 2 neutral cluster in time, with most energetic assumed to originate from Eg(recoil) calculated from 2 body kinematics Using eta decay kinematic we correct Eg(h) Cut on Eg(h) to reject background
Analysis versus EVCL • Stream correlation for MC charged RAD investigated: run RAD, RPI & RAD, KPM & RAD & RPI ALL RAD RPI KPM
Using new approach MC 2005: All Phys, runs 34410-34499 (12.7pb-1) Only RAD stream
Track Selection VS Vertex Selection • Best Results from track selection using PCA at IP parameters Vertex Track
Event Signature in RAD Mh Mppg (MeV) Preselection and Event Signature OLD: 2 PNC + VTX e=46% Lint(2001) =95.7pb-1 NEW: 2 PNC + 2 TRK e=49% Lint(MC2005) =12.7pb-1
Signal/background Opening angle between calculated and selected neutral cluster from pnc, rejects background
Two photons invariant mass Measured ALL 0 0 ALL 0 0 Corrected Before cuts ALL 0 0 ALL 0 0 Measured Corrected After cuts
Two photons invariant mass corrected variables ALL 0 0 100 MeV < M< 170 MeV ()=39% Bg=1%
Control Sample 0 ALL 0 0 BG
Outlooks • Analysis in RAD stream: • Ilaria’s cuts to reject BG • Evaluate efficiency • Control sample • Analysis in KPM+RPI stream: • Evaluate efficiency