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B º  π + π - : status of analysis

B º  π + π - : status of analysis. Vitaliano Ciulli Riccardo Ranieri Nicolò Magini. Generated B º  π + π -. At least 1 μ p t μ >4 GeV/c lη μ l<2.6 At least 1 B º  π + π - p t B >8 GeV/c lη π l<2.4 Hard interaction p t >10 GeV/c. ^. A CP sin(2α) b  m - _ _ b  m +.

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B º  π + π - : status of analysis

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  1. Bºπ+π-: status of analysis Vitaliano Ciulli Riccardo Ranieri Nicolò Magini

  2. Generated Bºπ+π- At least 1 μ • ptμ>4 GeV/c • lημl<2.6 At least 1 Bºπ+π- • ptB>8 GeV/c • lηπl<2.4 Hard interaction pt>10 GeV/c ^ ACPsin(2α) bm- _ _ bm+ Bºπ+π-: status of analysis

  3. MC Signal 32.7% Gluon Splitting 20.6% Flavour Excitation 46.7% Pair Production 9196 events simulated (4384 digitized) PYTHIA6.152CMSIM122 ORCA5.1.2 (oohit) [ORCA5.1.2 (digi)] Cross section σ=4622 fb Bºπ+π-: status of analysis

  4. Decay reconstruction ForwardKalmanFilter + ConnectionMachine pt>0.8 GeV/c lηl<2.4 Well identified muon Combinatorial on other opposite-charge tracks lMBrec(GeV/c2)-5.2794l<1 ? 50 MeV/c2 Resolution ? Bºπ+π-: status of analysis

  5. Background Br(BºK+π-) = (1.72±0.27)x10-5  4xBr(Bºπ+π-) 5.24 GeV/c2 mass peak 50 MeV/c2 resolution½ bkg over signalS/B=1/2 Other Two-body decaysS/B=1/1 Estimation of Two-body Background S/B1/3 CMS-TN 1994/328 CP Violation Study of the Bdºπ+π- decay for the Technical Proposal Bºπ+π-: status of analysis

  6. More on Background Official muon MC productionhttp://cmssun4.pd.infn.it/~ugs/cms/hlt/prod2001_new.html PYTHIA6.152CMSIM121ORCA5.1.1 (oohit)ORCA5.1.2 (digi) dataset mu_MB1mu_pt4(at least a true muon pt>4 GeV/c no pt cut) Events: 106562 Lumi: 0.4071 nb-1 σ=262 μb High lumi (=10 nb-1s-1) Rate = 10 nb-1s-1x262 μb= 2.62 MHz ^ Rate = 400 KHz CMS-IN 2000/053 CMS-NOTE 2001/011 Bºπ+π-: status of analysis

  7. List of cuts Kinematic cuts: ptB>10 GeV/c ptπ>5 GeV/c I=ΣΔR<1(pt/ptB)<0.1 Vertex cuts: SIP=tIP/σIP>3 cos(Δα)>0.995 χ2vtx<10 Mass cut: lMBrec(GeV/c2)-5.29l<1x0.05 Bºπ+π-: status of analysis

  8. Some plots SIP=tIP/σIP>3 ptB>10 GeV/c Bºπ+π-: status of analysis

  9. Some numbers on signal… Bºπ+π-: status of analysis

  10. …and background Bºπ+π-: status of analysis

  11. L1+L2 Trigger Rate=30 KHz L1+L2 Trigger cuts ptμ>10 GeV/c Events used: 11993 After trigger: 306 Efficiency ε=2.55% High lumi Rate= 70 KHz CMS-NOTE 2001/011 Results on L2 trigger reconstruction in single and di-muon topologies Bºπ+π-: status of analysis

  12. Single muon Trigger only L1+L2 Trigger cuts ptμ>10 GeV/c Signal Efficiency (9.1±0.4)% Background Efficiency (2.55±0.14)% Total selection Efficiency Signal (3.4±0.9)x10-3 Background (3.2-2.1+5.6)x10-10 3 Years Low Luminosity (3x20 fb-1=60 fb-1) Nsig=940±250 Nbkg=4800-3300+9000 N2body=2800±800 Bºπ+π-: status of analysis

  13. Sensitivity to sin(2α) D~0.416 CMS-TN 1994/328 CP Violation Study of the Bdºπ+π- decay for the Technical Proposal 1 Year Low Luminosity 10 fb-1 Time integrated analysis sensitivity: Bºπ+π-: status of analysis

  14. Concl… 4 aspects to be investigated further: • Two-body decay background estimated 2800±800 @ 60 fb-1 (events BºKπ needed) • Bug-fix on Bº lifetime this MC: t=13.85 ps instead of 1.56 ps (decay length normalized to expected one) new MC signal t=1.56 ps (some changes on Vertex cuts efficiencies…) Bºπ+π-: status of analysis

  15. …usion • New strategies to reject combinatorial background in udsc events (more statistics needed) • New ideas to enlarge Trigger Rate of signal events Bºπ+π-: status of analysis

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