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Taikan Suehara ICEPP, The Univ. of Tokyo
Tau & SUSY analysis Taikan Suehara ICEPP, The Univ. of Tokyo
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BG suppression cuts results
Backgrounds are suppressed to negligible level. Signal efficiency is ~23%, quite low but… Most cut events in first 2 cuts are with hard-photons Practical signal efficiency is considered ~75%
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Decay modes in Apol analysis
Branching ratio: 17.8% 3 body decay; pol. info is smeared t -> enn Branching ratio: 17.4% 3 body decay; same as enn mode t -> mnn Branching ratio: 10.9% Pol. can be directly observed by p distribution t -> pn Branching ratio: 25.2% Pol. of r can also be obtained by p distribution in r-rest frame (pol. of r is connected to pol. of t) t -> rn, r -> pp Branching ratio: 9.3% Currently not used because statistics is low t -> a1n, a1 -> ppp
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t -> pn selection results
Selection performance between geometries (look at the 2nd row from the bottom) Efficiency: not so different Purity: LDC’ > GLD > GLD’ > J4LDC t -> rn mode (decay 2p is mis-reconstructed as single) might be the reason (larger is better) LDC’ has advantage due to high CAL granularity.
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Apol calculation (pn mode)
Statistical error is almost the same for all geometries Value shifts are larger in GLD’/J4LDC due to the lower purity. Stat error in 500fb-1 Value shift due to the mode BG Values obtained by signal-only events!
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r -> pn selection results
3rd row from bottom: used as “no p0 mass cut”. 2nd row from bottom: used as “p0 mass cut”. Events with single neutral are survived with this cut. Most bottom row: used as “tight p0 mass cut”. Events with single neutral are eliminated with this cut. Clear difference by geometries: LDC’s the best, bigger is better in Jupiter’s.
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Apol calculation (rn mode)
Statistical errors are larger in GLD’/LDC, esp. with mp0 cut. Value shift is smaller than pn mode, negligible with mp0 cut. Stat error in 500fb-1 Value shift due to the mode BG Values obtained by signal-only events!
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イベント数 Singal : 2.3M / 500 fb-1 Bhabha : いまのpreselectionで20000/0.2fb-1
可能? Back to backをpreselectしてもよい (半分弱になる) Bhabha : いまのpreselectionで20000/0.2fb-1 5M / 50 fb-1 ggtautau: いまのpreselectionならおそらく500fb-1可能 ~0.1M / 500fb-1 他のモードはfull scanをやろうとしている
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SM separation cuts # of SM events becomes comparable to chargino after these cuts. No difference between geometries in this stage.
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Cut statistics (2) chargino neutralino
BG separation is efficient (see W/Z mass cut rows) Slightly better BG separation performance in GLD but almost within statistical fluctuations.
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Chargino mass fit results
Fitting function: 3rd polynomial (4 param) (center) / 0 (edge) convoluted with a Gaussian with s as linear function of energy (2 param) edge position: 2 param, total # of parameters = 8 Cheat fitting: 1. fix edge positions at true value, fit other 6 parameters. 2. fix those 6 parameters and fit edge positions. No significant difference between geometries.
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Neutralino mass fit results
Fitting function: Error function (left) x Complementary error function (right) Width of left and right is the same, # of parameters = 4 Cheat fitting: Same as chargino J4LDC gives slightly larger width than other two. Corresponding fitting error is enhanced.
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イベント数 SUSY: 500fb-1可能 (100kくらい) WW background – 10000 fb
4-jet 標準SMでは20fb-1 Preselectして増やすかどうか考える 4-jet + neutrino まだ考えてない こちらも全BGスキャン
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今日何を話しますか?
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Backup
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