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CP Violation in Penguin Decays

CP Violation in Penguin Decays. Denis Dujmic, SLAC. W. New Physics in Loop Decays?. FCNC Amplitude in SM. 3-6 QCD penguin 7-10 EW penguin. Dominant terms double-CKM and QCD-loop suppressed Decay rates small in Standard Model: <7 10 -5. Heavy non-SM particles can appear in loops

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CP Violation in Penguin Decays

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  1. CP Violation in Penguin Decays Denis Dujmic, SLAC SLAC DOE Review, Jun 7 2006

  2. W New Physics in Loop Decays? • FCNC Amplitude in SM 3-6 QCD penguin 7-10 EW penguin Dominant terms double-CKM and QCD-loop suppressed Decay rates small in Standard Model: <7 10-5 • Heavy non-SM particles can appear in loops • - large contribution possible, ~O(1) • - in general not CP-conserving • Study CPV in penguins: • - probe for new CP-violating phases SLAC DOE Review, Jun 7 2006

  3. Indirect CPV (beta) Tree decay, BF~10-3 Penguin decay, BF~10-5 Both have same CP asymmetry parameter 2 Im[l] = sin2b Test this prediction! SLAC DOE Review, Jun 7 2006

  4. Standard Model or Beyond? All penguins 0.50 ± 0.06 (3s difference!) New Physics? This could be the greatest discovery of the century. Depending, of course, on how far down it goes. SLAC DOE Review, Jun 7 2006

  5. SM Uncertainties CPV Parameter Example diagram CKM term t c SM pollution! u SLAC DOE Review, Jun 7 2006

  6. SM Uncertainties Predictions based on factorization models • - Theory estimates • Beneke, PLB 620 (2005) 143 • Cheng, Chua & Soni, PRD72:094003(2005) • HFAG BaBar+Belle average • ccK average Dsin2b QCDF, pQCD, SCET calculations agree SLAC DOE Review, Jun 7 2006

  7. Status of KKK0 CP Analysis SLAC DOE Review, Jun 7 2006

  8. Event Selection for B0→KKKS Branching fraction (reco. events) • fK0 makes only 15% of the total K+K-K0 branching fraction • What goes into B0→K+K-K0 Dalitz plot? 230 M BB pairs SLAC DOE Review, Jun 7 2006

  9. K+ L’=L B0 KS L K- B0→KKK0: CP Content • CP of final state not known! • - CP(K+K-) = even, CP(K+K-KS) = (-1)L • - need distribution of angular momenta L • Angular-moments analysis: qH Describe decay in terms of S and P-waves decaying into K+K- Compute wave strengths using moments of Legendre polynomials: S-P interf. S-wave P-wave SLAC DOE Review, Jun 7 2006

  10. B0→KKK0: Angular Moments [BABAR,PhysRevD71:091102(2005)] • BABAR’s – analysis of angular moments: Average moments computed using sPlot technique [Pivk, Le Diberder, physics/0402083] Outside of fKS region BABAR 230 MBB Belle 386 MBB (isospin) Belle’s method requires 1.7 times more data to have same error SLAC DOE Review, Jun 7 2006

  11. Sin2b from KKK0 Dalitz plot of K+K-KS consists of fKS (CP-odd) + S-wave (CP-even): BABAR, ~230MBB fK0S • split sample into fKS (CP-odd) and m(K+K-)>1.1 (CP-event) • treat any interference as syst. error fK0L In each mass region: KKKS History plots of CP asymmetry measurements: BaBar BaBar “K+K-K0” fK0 Belle Belle SLAC DOE Review, Jun 7 2006

  12. What More? Dalitz plot! Time-dependent Dalitz plot rate: Describe Dalitz plot amplitude in terms of (non)resonant components: Natural way to combine fK0 and high-mass KKK0 decays Best way to treat interference effects SLAC DOE Review, Jun 7 2006

  13. f reflections f [BABAR,hep-ex/0507094] D+,Ds+ X(1500) cc0 non-res Understanding KKK0 Dalitz plot m(K±KS) [GeV/c2] m(K+K-) [GeV/c2] -First B0->KKKS Dalitz plot analysis (time integrated) - Next: simultaneous fitting of entire Dalitz plot fK0+KKK0 and extraction of CPV parameters SLAC DOE Review, Jun 7 2006

  14. Other Progress in Penguins • Improvements of BABAR analyses (using 230 M BB pairs): • Add submodes of existing channels: • KS->p+p- is only 34% of all K0 decays • Add KL: h’KL, KKKL • Add KS->p0p0: KSKSKS • 2) Add channels with high background: • - p0p0KS, rKS - Stat. power from additional modes alone: s(sin2b)stat ~ 0.16 • - Total penguin average for BABAR: s(sin2b) ~ 0.09 SLAC DOE Review, Jun 7 2006

  15. Performance for beta Total error on sin2b as of Winter06 BABAR ~230 MBB Belle ~386 MBB BABAR outperforms Belle even with less data - better analysis techniques - bigger boost, better PID SLAC DOE Review, Jun 7 2006

  16. Summary and Plans • All channels will be updated with 2006 dataset • BaBar error on sin2b(h’K0) < 0.1 • BaBar+Belle combined penguin error ~0.04 • SLAC contribution: • KKKS KS→p+p-(Dujmic), KS→p0p0(Thompson,Roodman) • rKS, f0KS -> p+p-KS (Graham) • fKS, f->3p (Suzuki) • p0p0KS (Allen, Roodman): • Kp: (Allen, Roodman), • Dalitz plot: K+KSKS, K+K+K- (Thompson,Dujmic,Roodman) • conveners of physics working group (Dujmic,Graham) beta Direct CPV SLAC DOE Review, Jun 7 2006

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