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Status report B D 0 K 0 decay G.Calderini M.Carpinelli N.Neri BaBar Italia Capri 11 Apr 2003 INFN Pisa
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Capri 11 Apr 2003 BaBar Italia2 Motivations of the analysis Possibility to measure the weak angle. M. Gronau and D. Wyler, Phys. Lett. B 265, 172 (1991). Dalitz plot can help solving the 8-fold ambiguity of the value. R.Aleksan et al. hep-ph/0209194 (Nov 2002) Measurement of the branching ratio of non resonant decay.
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Capri 11 Apr 2003 BaBar Italia3 Extension to Wyler-Gronau method in B - D 0 K - decays Measuring through amplitude relationship he decay amplitude varies in the Dalitz plot The Non Resonant decay is color allowed : larger interference.
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Capri 11 Apr 2003 BaBar Italia4 Measurement of Interference amplitudes for each region i of the Dalitz plot Relation among the number of measured events in each region i R.Aleksan et al. hep-ph/0209194 (Nov 2002) both color allowed for Non Resonant decay
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Capri 11 Apr 2003 BaBar Italia5 Feynman diagrams (Non Res) W K+K+ D0D0 B+B+ W D0D0 K+K+ B+B+ The leading tree diagrams are both color allowed Interference amplitudes are both large b->c quark transition b->u quark transition leading diagram
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Capri 11 Apr 2003 BaBar Italia6 MC Sample Releases 10.3.1x SP4 B + generic: 24.44 fb -1 B 0 generic: 14.87 fb -1 ccbar: 7.60 fb -1 uds: 3.63 fb -1 signal MC: D 0 K + 0 NR: 3000 Ev D *0 K + : 3000 Ev D 0 K *+ : 18000 Ev
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Capri 11 Apr 2003 BaBar Italia7 List of candidates Release anal13b B list:BchToD0KPi0_Default,BchToD0barKPi0_D efault D0 list: D0ToKPi_Loose into hadronic modes: K K list : GTL list : GTL K3 , K 0 will be added D0 into CP modes KK, , s will be added K list: GTL list Pi0ToGGLoose
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Capri 11 Apr 2003 BaBar Italia8 Selection cuts Event shape: FoxWol < 0.3 |cos( T )| < 0.75 | E|<200MeV P( B+ 2 )>0.1 D0 selection K :KMicroTight doMass true P( D0 2 )>0.01 |m D0 -m PDG |<3 K selection KMicroVeryTight p lab <2.75GeV 0 selection doMass true p lab >0.75GeV |m 0 -m PDG |<3 selection E lab >100MeV
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Capri 11 Apr 2003 BaBar Italia9 Event Shape |COS( T )|<0.75 FoxWol<0.3 BchB0ccbaruds sigNR keep65%60%20%22%75%
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Capri 11 Apr 2003 BaBar Italia10 Work in Progress Fisher Discriminant (CLEO): 9 cones + cos B + cos T CLEO Fisher SIG continuum
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Capri 11 Apr 2003 BaBar Italia11 D 0 Selection probD0>0.01 KMicroTight BchB0ccbaruds sigNR keep38%30%19%3.5%45%
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Capri 11 Apr 2003 BaBar Italia12 Work in Progress Added new info in the ntuple: D 0 flight length, beam-spot, primary vertex Time(ps) D 0 proper time distribution
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Capri 11 Apr 2003 BaBar Italia13 Pi0 Selection BchB0ccbaruds sigNR keep25%34%28%55%86% P lab >0.75 GeV/c
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Capri 11 Apr 2003 BaBar Italia14 Bkg composition E distribution M ES distribution The number of events is scaled to 100 fb -1
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Capri 11 Apr 2003 BaBar Italia15 BKG composition Bch: 6 B decay not correctly reconstructed 12 combinatorial bkg events 5 false D0, 3 false Pi0, 4 other B 0 : 1 B decay not correctly reconstructed 6 combinatorial bkg events 2 false D0, 2 false Pi0, 2 other ccbar: 5 combinatorial events 1 false Pi0, 4 other B chargedB neutralccbarudsSigNR Event 18 4.2 Scale=4.09 [3.89-11.77] @90%CL Scale=6.72 [2.43-9.27] @90%CL Scale=13.16 <2.3 @90%CL Scale=27.50 30 5.5 Scale=1 Scaled Event 734765<6330 B - D* 0 - D 0 0 - 0 misid lost 0 soft
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Capri 11 Apr 2003 BaBar Italia16 Multiple candidates We found 1 candidate per event in the 3 sigma [M ES, E] with present selection criteria. IF multiple candidate event is found we select the best candidate with the minimization of the 2 : This criteria in principle does not bias M ES, E distribution.
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Capri 11 Apr 2003 BaBar Italia17 Expected number of events We can estimate the order of magnitude of NR BR assuming it equal to RES one: BR( D 0 K* +, K* + K + ) BR( D 0 K + ) NR 1-210 -4 BR( D 0 K* + ) = 6.1 x 10 -4 [CLEO] We assume the BR= 1 10 -4 Efficiencies on signal MC after severe cuts with K mode: 7% = 30 events Adding K3 K we can expect 3 times the number of events.
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Capri 11 Apr 2003 BaBar Italia18 Work in Progress Added new modes into the ntuple: K , K , K3 KK, SP5 signal MC: More MC signal NR produced with moose: 15000 events available (before we had 3000) Started to write the BAD. Discovered a bug in the Official Tag Bit for DKPi. Contacted the Breco convener and writing the new sequence for the next reprocessing. Planning to run on data and MC filtering on an inclusive tag bit: D 0 + ntrkLoose>=3
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Capri 11 Apr 2003 BaBar Italia19 Next step Starting production on a consistent generic MC and DATA sample. BBbar, continuum, signal, cocktail D (*) K (*) Run1, Run2 Optimizing the Fisher discriminant approach. Optimization of the cuts. Starting cross checks using DATA-MC comparison.
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