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Rare B Decays at

Rare B Decays at. BABAR. Mousumi Datta University of Wisconsin, Madison On behalf of the BaBar Collaboration XII International Workshop on Deep Inelastic Scattering 14-18 April 2004. Outline. Introduction Motivation Experimental techniques Rare hadronic B decays

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Rare B Decays at

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  1. Rare B Decays at BABAR Mousumi Datta University of Wisconsin, Madison On behalf of the BaBar Collaboration XII International Workshop on Deep Inelastic Scattering 14-18 April 2004

  2. Outline • Introduction • Motivation • Experimental techniques • Rare hadronic B decays • Radiative and electroweak B decays • Purely leptonic B decays • Summary All results are preliminary unless referenced. DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  3. SM and Rare B Decays • Good agreement between Standard Model (SM) and the experimental results up to now. • To be sensitive to possible new physics (NP) and to test SM  consider decays with small SM rates. • Look at : • Processes dominated by penguin loops • CKM suppressed decays • Purely leptonic decays Rare B Decays DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  4. SM and Rare B Decays (cont’) • New physics particles in loops might show up in: Different rates, kinematic distributuios than SM only Different CP violation than SM only Constrain the SM • Time dependent CP measurements (L. Li Gioi’s talk) • Direct (time integrated) CP measurement • Decay rates • Compare theoretical predictions • Constrain CKM parameters : |Vtd/Vts| from BK*,  • Kinematic distributions : K*, Xsl+l- DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  5. Direct CP Asymmetry • Different decay rates for B  f and B  f • need2 decay amplitudeswithdifferent weak phase and different strong phase: Weak phase difference Strong phase difference Penguin-dominated decays like B  K(*), K, K* have small ACP in SM sensitive to extra CP-violating phases due to NP DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  6. PEP-II Luminosity Performance Best Peformance PEPII peak Luminosity : 8.305x1033 cm-2 sec-1 24 hours : 660.5 pb-1 124.1106 BB 89.7106 BB 82 fb-1 on-peak data for analysis Run 4 data taking in progress: ~100 fb-1 by July 2004. DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  7. signal background Standard Variables in (4S) Frame e+e-(4S)  BB B produced almost at rest in (4S) frame For B decay with no missing particles use beam energy to constrain mass and energy of the reconstructed B 0 for signal mB for signal background E and mESprovide uncorrelated measurement of energy and mass DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  8. Rare Hadronic B Decays • Suppressed at tree(T) level due to Cabbibo, FCNC, etc. Significant Penguin (P) contribution. • Hadronic decay modes covered in the talk Tree diagram Penguin diagram B  , K, KK B → ρρ and ρK* B  K(*)/ B  (')K(*) and (')/ B  () () DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  9. B d u u (PRL, hep-ex/0303028) • Measure eff from time dependent CP analysis of B0+- decay • Constrain  using isospin connection for decays Bp+p-, p+p0, p0p0 Tree CKM suppressed B++0 @ 82 fb-1 B0+- @ 82 fb-1 Penguin diagram B+- Color suppressed tree for B00 BF(B0+-)= (4.70.60.2)10-6 (PRL, hep-ex/0207055) DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  10. B (Cont’) B000 @ 113 fb-1 Observation of significant excess of 00 events 4.2  BF(B000) = (2.1 ± 0.6 ± 0.3)10-6 Observed events = 46 ± 13 ± 3 (PRL ,hep-ex/0308012) SM prediction BF ~ (0.3-1.1)10-6 Bound on penguin pollution Grossman Quinn bound PRD 58 (1998) 017504 With WA Br(B00 ) |-eff |<48o at 90% c.l.

  11. PRL Summary of BF (10-6) for K,  and KK Ratio of BF for  and K sensitive to angle  Time dep. CP analysis of Ks0 using 113 fb-1 Measure sin2 Acpconsistant with zero KK decays more sensitive to rescattering : No sign of rescattering (FSI) yet DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  12. K and  • Significant Penguin contribution • Isospin symmetry holds well for penguin dominated modes ( EW penguin small) • Need more statistics for further constraint << 1/2 if tree only Isospin ratios ~1 Isospin sum rule(Gronau et. al. (2003), hep-ph/0307095)(Lipkin) BaBar: 1.21  0.13 Belle(LP03): 1.25  0.15  New Physics ? < 4% *Ratios calculated by speaker, assuming errors are uncorrelated DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  13. B → ρρ, ρK* and K(*)/ • Time dependent CP analysis: Sin(2)K0 and Sin(2eff) from  • Search for direct CP violation. BVV: Longitudinal polarization ( fL≡ L /  ) Expect: fL ~ 1 – O(M2V/M2B) DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  14. B → ρρ and ρK* PRL L=82 fb-1 B0 +  - NS = 224 ± 29 Time dep. CP measurement for +-also updated with 113 fb-1. (preliminary) 100% Longitudinal Polarization  CP even | - Eff| < 13o () at 68% CL Grossman Quinn bound PRD 58 (1998) 017504 DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  15. hep-ex/0309025 hep-ex/0307026 B   K(*)/ L=82 fb-1 • Expect similar BF all K(*)modes • BF(+)<410-7 [90% CL] (No indication for rescattering – as KK) • Polarisation small BK*0 full angular analysis with 113 fb-1 fL = 0.52  0.07  0.02 (preliminary) • Small fL still not understood – may be related to penguins • [Bauer, Pirjol, Rothstein, Stewart, hep-ph/0401188; Kagan] DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  16. (')K(*) and (')/ K, hK* enhanced Interference K, K* suppressed H Lipkin Phys Lett B254 (1991) 247 CKM suppressed Flavour singlet diagram: Also important for K* Similarly for K0, K*0 except no external tree. Decays () and + are dominated by tree diagram as penguin diagrams are suppressed. DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  17. (,)(K,,K*,,0), 0, 0 L=82 fb-1 K BF 3-10 times larger than initially expected values. In agreement with recent NLO QCD prediction (Beneke and Neubert, (2003) Nucl. Phys. B 651, 225). PRL 91, 161801 2003, PRL 92,061801 2004 K* measurement not precise enough to determine the presence of flavor singlet component. Submitted to PRD hep-ex/0403025 Large asymmetry predicted for +, small for + Chiang, Gronau, Luo, Rosner and Suprun [hep-ph/0307395] DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  18. Submitted to PRL Isoscalar (,,,)(,,,) L=82 fb-1 8 of 10 combinations , , , , , , ,  (not , ) CLEO DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  19. Predictions for KsTime Dependent asymmetry S,C Correlated bounds on CP asymmetries in B0Ks . [Gronau, Rosner & Zupan, hep-ph/0403287, April 2004] HFAG average From 00, K+K-, 0, ’ From 00, 0, 0’, , ’’, ’ Similar bounds from [Grossman-Ligeti-Nir-Quinn, PRD 68, 015004 (2003).] Previous bounds DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  20. Rare decays aren’t so “rare” DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  21. B/ :(PRL, hep-ex/0306038) BK* (Preliminary) Iso-spin asym. 0-= = 0.0510.044(stat) 0.023(sys) 0.024(R+/0) SM prediction: (+5 to +10)% Prediction Measurement BF(B0K*0(K+-,K0s0)) 7.5  3.0 3.920.200.24 BF(B+K*+(K+0,K0s+)) 7.5  3.0 3.870.280.26 ACP(K*(K+-, K+0,K0s+) < 1% -0.0130.0360.010 BF(B00(+-)) 0.5 – 0.75 < 1.2 BF(B++(+0)) 0.8 – 1.5 < 2.1 BF(B0(+- 0)) 0.5 – 0.75 < 1.0 10-5 L=82 fb-1 @ 90% CL L=78 fb-1 10-6 BK* and / Time dep. CP analysis B0  K*0(Ks0) with 113 fb-1 DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  22. Semi-inclusive BXs Submitted to PRL L=82 fb-1 Xs fully reconstructed in 12 exclusive self-tagging modes Acp = 0.0250.050.015 (for total sample) Acp = -0.040.100.02 (for high purity sample) DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  23. PRL, hep-ex/0308042 L=113.1 fb-1 BK(*)l+l- BKl+l- >8 SM Prediction (10-6) BF(B → Kl+l-) = 0.350.12 BF(B → K*e+e-) = 1.580.49 BF(B  K*+-) = 1.190.39 Ali et al. (hep-ph/0112300, 2001) BK*l+l- 3.3  DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  24. L=82 fb-1 Semi-inclusive BXsl+l- • Less theoretical uncertainty • Observables: BF, m(l+l-), m(Xs), AFB(m(l+l-)) Xse+e- Xs+- • Xs reconstructed in 10 modes: uncounted states ~25% of the total rate • In signal region m(l+l-)> 0.2 GeV/c24110(stat)2(syst) events observed Xse Xsl+l- Prediction for m(l+l-)>0.2 GeV/c2: (4.20.7)10-6 (Ali, hep-ph/0210183, 2002) DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  25. BK • FCNC transition • 2 ’s in the final state Reconstruct one B & look for signal in the recoil side Hadronic B Sample Semileptonic B Sample 50.7 fb-1 BF < 9.4 x10-5 @ 90% CL B-g K-nn simulation Data 80.7 fb-1 BF < 1.05 x10-4 @ 90% CL Combined limit @ 90% CL < 7.0 x 10-5 SM Expectation: ~ 410-6 DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  26. B+l+ • B+l+ : SM expectation: • BF(B++) ~ 410-7 • BF(B++) ~ 910-5 • Provide measurement of fB|Vub| • Sensitive to charged Higgs, leptoquarks. • Purely leptonic decay are helicity suppressed in SM Data B++ at 81.4 fb-1 L=81.4 fb-1 BF(B++) < 6.610-6 @ 90% CL (PRL) B++ simulation DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  27. B L=81.9 fb-1 • Multiple ’s in the final state  Reconstruct one B & look for signal in the recoil side. Semileptonic Sample Hadronic B Sample Includes  e, , , 0, 3 total~ 0.028 % BF < 7.7 x10-4 @ 90% CL Semileptonic B Sample Includes e,  total ~ 0.07 % BF < 4.9 x10-4 @ 90% CL Eextra (GeV) Combined limit BF < 4.1 x 10-4 at 90% CL Existing tightest limit (L3) BF < 5.7 x 10-4 at 90% CL DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  28. Summary • Large amount B mesons produced at B-factories • First observation of many rare decay modes • More precise measurement of BFs • Tighter upper limits on BFs • BaBar haven’t seen evidence of direct CP violation yet. Precise measurements of ACP in future will enable further tests of models. • No strong evidence of NP. • Measurements and search for many more rare decay modes continuing • The expected increase in luminosity of the B Factories promises a continuing, rich harvest of physics Stay tuned for the summer results. DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  29. Backup Slides

  30. PEP-II Asymmetric B-Factory at SLAC Asymmetric collider operation at (4S) resonance (Ecms=10.58 GeV) 3.1 GeV e+ and 9 GeV e- B-mesons in lab have =0.56 B B production threshold DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  31. EMC 6580 CsI(Tl) crystals 1.5 T solenoid DIRC (PID) 144 quartz bars 11000 PMs e+ (3.1 GeV) e- (9 GeV) Drift Chamber 40 stereo layers Instrumented Flux Return iron / RPCs (muon / neutral hadrons) Silicon Vertex Tracker 5 layers, double sided strips The BaBar Detector SVT: 97% efficiency, 15 mm z hit resolution (inner layers, perp. tracks) SVT+DCH: (pT)/pT = 0.13 %  pT+0.45 % DIRC: K- separation 4.2  @ 3.0 GeV/c  2.5  @ 4.0 GeV/c EMC: E/E = 2.3 %E-1/4 1.9 % DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  32. Other B qq e- e+ e- e+ Signal B u,d,s,c background B Signal Arbitrary Units Fisher Discriminant Continuum Suppression B decays: isotropic Continuum (u,d,s,c): jet-like • Examples of topological variables using these properties: • Thrust • Energy cones Variables are used in a Fisher or a Neural Net (NN) DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  33. BF & ACP for B , K, , K Measure eff from time dependent CP analysis of  BF of  and K are in good agreement with theoretical expectation. DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  34. Preliminary L=113 fb-1 B K*0full angular analysis Fit results Direct rate asymmetries Triple-product asymmetries DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  35. B K*0 Weak evidence for FSI (2.3s) B rr fL=0.520.070.02 Triple-product asym. (1.7s) (would be evidence for New Physics Datta&London hep-ph/0303159) No evidence for Direct CP violation DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  36. Preliminary First Observation B0f0(980)Ks , f0+- L=111 fb-1 • Structure of this scalar meson obscure. Recent studies favor usual qq states [hep-ph/0011191(2000)] BABAR 94±14(stat)±6(syst) evts L=111fb-1 Total Continuum All bgk. • Decay can be dominated by bsss penguin • ss sizeable • buus tree doubly Cabbibo suppressed compared to leading penguin • Time dependent CP measurement • (see L. Ligioi’s talk) BABAR Total Continuum All bgk. BF(B0f0(980)(+-)K0) = (6.0  0.9  0.4  1.2)10-6 DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  37. B a0(980)(K,p,KS) G-parity suppressed Dominant tree diagram a0p a0K Dominant penguin • a0+negligible compared with a0-(G-parity)  “self-tagging” • a0K expected to be small (Wilson-coefficient cancellation)Chernyak, PLB 509, 273 (2001).

  38. B a0(980)(K,p,KS) L=82 fb-1 PRELIMINARY B is B(B a0X)B(a0p) • Unbinned ML fits (89M BB events); a0 , ,3 • Only previous search from BABAR (20 fb-1, LepPho 2001) • Found 3.7 evidence for B0 a0(980)-+ • Do not confirm that with substantially improved sensitivity • Studies indicate the previous result was a statistical fluctuation

  39. L=82 fb-1 B KS p+p- branching fraction • Measurement of the branching fraction integrated over the Dalitz plot • Careful corrections for efficiency across Dalitz plot • Consistency check from B0 D-+ with D-  KS- B(BK0+-) = (43.8 ± 3.8 ± 3.4)10-6 • Comparable to, but more precise than, previous results • CLEO (50 ± 10 ± 7)10-6 • Belle (45.4 ± 5.2 ± 5.9)10-6

  40. L=113 fb-1 B0→K+K-KS and B+→K+KSKS • 3 body decay B0→K+K-KS (excluding B0→K0) Time dependent CP analysis: Sin(2) • Determine CP-even fraction using • Branching fraction measurements • Isospin symmetry [Belle Collaboration, Phys. Rev D69, 012001 (2004)]: BABAR B0→K+K-KS 201±16 events L=111 fb-1 B+→K+KSKS 122±14 events BF(B0→K+K-K0)= (23.8±2.0±1.6)×10-6 BF(B+→K+KSKS)=(10.7±1.2±1.0)×10-6 ƒeven=0.98±0.15±0.04 Acp(B+K+KsKs) = -0.042  0.114(stat)  0.02(syst) DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  41. Charmless B+h+h-h+ (h=K,) PRL (hep-ex/0304006) • Search for direct CPV. Measure  through the interference between various charmless decays and c0 resonance(Blanco et al, Phys.Rev.Lett.86,2720(2001)) • Measurement of B+++- can be used to reduce uncertainty in  measurement(Snyder and Quinn, Phys. Rev. D48, 2139(1993)) L=81.8 fb-1 B+ + - + B+→K+-+ B+→K+K-K+ DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  42. Submitted to Phys.Rev.Lett. (hep-ex/0308065) L=56.4 fb-1j K*0(892) D0 (2S) c0 (veto) J/ f0(980) 0 higher K*0 Exclusive Branching Fractions of B+K+-  + • Search for direct CPV • Measure  through the interference between various charmless decays and c0 resonance • K*0(892)+ BF result significantly higher than prediction from many factorization models. • Limit on non-resonant component   dependent interference will be hard to measure Dalitz plot divided into 8 regions DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  43. Inclusive bs L=54.6 fb-1 Onpeak data Signal region Background expectation Signal Region 2.1 < E* < 2.7 GeV DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  44. B0e B0+- B0e+e- L=54.4 fb-1 B0l+l- • FCNC process • B0l+l- : SM Expectation: • BF(B0e+e- ) : 1.910-15 BF(B0+-) : 8.010-11 • In various SUSY models BF enhanced, B0eallowed. Upper limits at 90% CL: BF(B0e)<2.110-7 BF(B0e+e-) < 3.310-7 BF(B0+-)< 2.010-7 DIS 2004 Mousumi Datta, University of Wisconsin-Madison

  45. Recoil Analysis For search of rare decays like BK, B .... sideband peak Breco Brecoil D* Y(4S) l p n ‘other’ B • Fully reconstructed B Meson in • Hadronic decays: D(*)(n) • Semileptonic decays: D(*)l  (statistically independent) • Look for process of interest in the Recoil Hadronic B Sample Pro: Background suppression! Con: Statistics limited N BB = (1.670.09)105 @ 81.9 fb-1 DIS 2004 Mousumi Datta, University of Wisconsin-Madison

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