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BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 1 Antonio Limosani JSPS Fellow (KEK-IPNS JAPAN) BMN 2006 2006 2010.

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Presentation on theme: "BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 1 Antonio Limosani JSPS Fellow (KEK-IPNS JAPAN) BMN 2006 2006 2010."— Presentation transcript:

1 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 1 Antonio Limosani JSPS Fellow (KEK-IPNS JAPAN) BMN 2006 2006 2010

2 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 2 Motivation Fundamental parameter in SM CKM mixing matrix element Unitarity Triangle Side-length Directly test the mechanism for CP Violation in SM

3 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 3 Measurement type - Inclusive MXMX hadrons Charged lepton neutrino q2q2 p lepton 1. Cuts to avoid B  X c l 2. Measure 3. Extract V ub Quark level B

4 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 4 HFAG V ub Average SourceError (%) Stat2.2 Exp2.8 Bkgd model1.9 Signal model1.6 HQE: m b 4.2 SSF/matching3.8 WA1.9 Total7.3

5 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 5 Fully reconstructed B sample Dedicated exclusive channels are searched for in reconstruction –180 decay chains –Clean environment but small sample – Reconstruction Efficiency ~ 0.3% Reconstructed modes

6 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 6 Fully reconstructed B analysis Fully reconstruct the event  4-momenta of both B’s are known Identify lepton from B  Xl on the signal side Use Particle ID to reconstruct the hadronic system and calculate Estimate the signal B  X u l

7 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 7 Belle M x Analysis @ 253/fb  B=(1.24±0.11(stat) ±0.09(sys) ± 0.08(b->u) ±0.03(b->c))x10 -3 V ub =4.09 x10 -3 (1 ±0.049 (stat) ±0.035 (sys) ±0.031 (b->u) ±0.011 (b->c) ±0.045 (SF) ±0.038 (theory)) M x < 1.7 GeV/c 2 Phys.Rev.Lett.95:241801,2005 (hep-ex/0505088)

8 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 8 M x Analysis : Statistical Error projections Luminosity(/ab)0.251.05.050.0 Signal to Noise0.651.52.0 B tag efficiency0.30.40.6 |V ub | stat %4.92.00.70.2

9 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 9 Luminosity(/ab)0.251.05.050.0 Detector simulation3.5 Background model (charm) 1.11.00.5 Signal modelDepends of HQE parameters : b-quark mass, m b, dominates Extrapolating to full branching fraction (SF) Theory |V ub | : Matching scales, SSF Theory/Exp |V ub | : Weak Annihilation |V ub | stat % M x Analysis : Systematic & Theory Error projections

10 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 10 b-quark mass, m b (4.60 +/- 0.04) GeV/c 2 Luminosity(/ab)0.251.05.050.0 Exp error: Moments data 0.0250.020.01 Theory error Vary  s, m b, m c 0.03 Total error0.04 0.03 M x Analysis : b-quark mass Precision on m b hits theory floor!

11 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 11 M x Analysis : Systematic & Theory Error projections Luminosity(/ab)0.251.05.050.0 Detector simulation3.5 Background model (charm) 1.11.00.5 Signal model3.12.82.62.4 Extrapolating to full branching fraction (SF) 4.54.23.93.7 Theory |V ub | : Matching scales, SSF 3.6 Theory/Exp |V ub | : Weak Annihilation 3.02.01.0

12 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 12 M x Analysis : Total Error projections Luminosity(/ab)0.251.05.0 |V ub | total %9.47.77.06.8 |V ub | exp %6.14.13.6 |V ub | theory %7.26.56.05.8

13 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 13 M x Analysis : Total Error projections

14 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 14 V ub with Reduced Model dependence Phys.Rev.Lett. 96 (2006) 221801 (hep-ex/0601046 ) (BABAR Collaboration) M x < 2.5 GeV/c 2 V ub =3.84 x10 -3 (1 ±0.182 (stat) ±0.036 (sys) ±0.056 (b->u) ±0.038 (b->c) ±0.000 (SF) ±0.026 (theory))

15 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 15 Error projections Luminosity(/ab)0.11.05.050.0 Statistics18.25.72.60.8 Detector simulation3.6 Background model (charm) 3.83.52.0 Signal model3.12.92.72.5 Extrapolating to full branching fraction (SF) 0.0 Theory |V ub | : Perturbative 3.6 Total19.58.96.66.1

16 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 16 Error projections

17 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 17 Measurement types - Exclusive Theoretical description parameterised by a single form factor  pion Charged lepton neutrino q2q2 p lepton B Experimentally less ambiguous than the inclusive decay Determine  using unquenched lattice QCD calculations. Model independent Limited to q 2 >16 GeV 2 /c 2

18 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 18 Current status - Exclusive

19 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 19 V ub from  B(B->  lv: q 2 >16 ) Three methods 1. Untagged: Systematic error 4% @ 0.2ab -1 (BABAR) Previous to this study consensus was one couldn’t get lower than 8% 2. Semileptonic tag : Systematic error 10% @ 0.25ab -1 (Belle) Systematic dominated by statistics of control sample Total error 2.9% @ 5ab -1 and 2.1% @ 50ab -1 3. Full B reconstruction tag : Systematic error 2.1% @0.5ab -1 (Belle) Total error : 40% @0.5ab -1 (statistics dominated) Total error : 27% @1.0ab -1 Total error : 15% @5.0ab -1 (improvement in full recon efficiency) Total error : 5% @50ab -1 Theoretical uncertainties (Lattice QCD) Phys. Rev. D73:074502 (2006) Currently error is at 12%, but it’s anticipated that it will reach 5%.

20 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 20 Future of Exclusive V ub

21 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 21 Future of V ub Tagged analyses are essential At logged luminosities of 5/ab and 50/ab precision is limited by systematic and theoretical uncertainties ~ 5% Co-ordinated experimental and theory studies are needed to reduce this error further b-quark mass

22 BNM Tsukuba (KEK) Sep 13-14 2006 Antonio Limosani KEK Slide 22 Backup Slides


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