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JOLANTA BRODZICKA Institute of Nuclear Physics, Krakow April 09, 2003 Doubly charmed B decay B ± D0 D0 K ± ( for ~78 fb -1 )

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Presentation on theme: "JOLANTA BRODZICKA Institute of Nuclear Physics, Krakow April 09, 2003 Doubly charmed B decay B ± D0 D0 K ± ( for ~78 fb -1 )"— Presentation transcript:

1 JOLANTA BRODZICKA Institute of Nuclear Physics, Krakow April 09, 2003 Doubly charmed B decay B ± D0 D0 K ± ( for ~78 fb -1 )

2 JOLANTA BRODZICKA April 09, 2003 B DDK Analysis details at least 5 good tracks : abs(IP_dz)< 5cm abs(IP_dr)< 0.4cm R 2 < 0.3 K ± : P( K/ ) > 0.4 ± : P( /K ) > 0.1 D 0 reconstruction (see my December ICPV talk for details) B ± D 0 D 0 K ± reconstruction : B vertex fit: with IP and B lifetime constraints, cl_B > 0 (except B decays with D 0 K 0 ) no cos THR, cos PROD shape cuts M bc > 5.2 GeV < E < 0.35 GeV BF ~ 28% ( K, K3, K 0, K s, K s KK, KK ) M (D REC ) cut: ± 20MeV ( D 0 K 0 : ± 50MeV) vertex fit (conf_level>0.), mass constraint fit

3 JOLANTA BRODZICKA April 09, 2003 B DDK best B candidate choice method (see my December ICPV talk for more details) B(M D ) LR_D (M D ) LR_D (M D ) = S(M D ) + D probability : S(M D ), B(M D ) parameterization from M D fit B probability for B ± D0D0BK ± : LR_B = LR_D 1 × LR_D 2 best B candidate : with max LR_B best = 82 % (for (kpi)(kpi) ) (estimated from rejected MC events DE, Mbc distributions and correlations between accepted and rejected B candidates ) for B ± D0D0BK ± (kpi)(kpi) reconstr. eff is 15% efficiency lost due to B_best choice method is 0.9% choice method efficiency

4 JOLANTA BRODZICKA April 09, 2003 B DDK B ± D0 D0B K ± D0,D0B K Mbc signal box: abs( E)<25MeV Mbc>5.265 GeV S=28.7±6.5 BF = ( 1.53 ± 0.35 ) * = 15.0% eff = 2.21 * N/2MeV E N/7.5MeV

5 JOLANTA BRODZICKA April 09, 2003 B DDK B ± D0 D0B K ± LR > 0.04 signal box: abs( E) GeV ( for K 0 –45< E<25MeV ) S=68.6 ± 16.4 BF = ( 1.64 ± 0.39 ) * eff = 4.91 * E N/7.5MeV N/2MeV Mbc

6 JOLANTA BRODZICKA April 09, 2003 B DDK B ± (3770) K ± hypothesis (3770) D0 D0B MASS D0D0B for signal_box events S = 2.2 ± 2.5 N/14MeV fitted function: BW+sqrt(1-thr/x)*pol_3 BW position and width fixed to nominal (3770) values D0,D0B K LR > 0.04 M(DD) resolution at (3770) region reconstructed M(D0D0B) for spike generated ~1.MeV N/0.25MeV S = 15.9 ± 6.2

7 JOLANTA BRODZICKA April 09, 2003 B DDK MASS D0D0B for 3body MC B ± D0 D0B K ± D0,D0B K 20MeV bins reconstruction efficiency vs. Mass (D0D0) for 2body MC B ± (3770) K ± D0,D0B K MASS D0D0B = 15.0% = 16.0% 2MeV bins correct now! (Previously wrong generated M(DD) distributions)

8 JOLANTA BRODZICKA April 09, 2003 B DDK B ± D0 D0B K ± E distributions vs. M(D0D0B) LR>0.02

9 JOLANTA BRODZICKA April 09, 2003 B DDK B ± D0 D0B K ± E distributions vs. M(D0D0B) projections LR>0.02

10 JOLANTA BRODZICKA April 09, 2003 B DDK E projections for different M(D0D0B) 80MeV regions LR>0.02

11 JOLANTA BRODZICKA April 09, 2003 B DDK B ± D0 D0B K ± fitted signal in each M(DD) 80MeV bin LR> lost signal box (partially reconstructed D*D*K ) ( fully reconstructed DDK ) 1 st bin Psi(3770) region: 19 ± 6 lost signal box (partially reconstructed D*DK ) M(D0D0B) Signal\80MeV


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