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SLAC DOE Review, Jun 7 20061 CP Violation in Penguin Decays Denis Dujmic, SLAC
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SLAC DOE Review, Jun 7 20062 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 W
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SLAC DOE Review, Jun 7 20063 Indirect CPV (beta) Tree decay, BF~10 -3 Both have same CP asymmetry parameter 2 Im[ ] = sin2 Test this prediction! Penguin decay, BF~10 -5
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SLAC DOE Review, Jun 7 20064 Standard Model or Beyond? New Physics This could be the greatest discovery of the century. Depending, of course, on how far down it goes. All penguins 0.50 ± 0.06 (3 difference!)
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SLAC DOE Review, Jun 7 20065 SM Uncertainties CKM term Example diagram CPV Parameter SM pollution! t c u
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SLAC DOE Review, Jun 7 20066 SM Uncertainties - Theory estimates Beneke, PLB 620 (2005) 143 Cheng, Chua & Soni, PRD72:094003(2005) -HFAG BaBar+Belle average -ccK average Predictions based on factorization models sin2 QCDF, pQCD, SCET calculations agree
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SLAC DOE Review, Jun 7 20067 Status of KKK 0 CP Analysis
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SLAC DOE Review, Jun 7 20068 Event Selection for B 0 → KKKS All K + K - K S KSKS 24.7 10 -6 (530±28) 4.2 10 -6 (114±12) Branching fraction (reco. events) K 0 makes only 15% of the total K + K - K 0 branching fraction What goes into B 0 → K + K - K 0 Dalitz plot? 230 M BB pairs
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SLAC DOE Review, Jun 7 20069 B 0 → KKK 0 : CP Content CP of final state not known! - CP(K + K - ) = even, CP(K + K - K S ) = (-1) L - need distribution of angular momenta L Angular-moments analysis: K+K+ KK B0B0 KSKS L L’=L HH Compute wave strengths using moments of Legendre polynomials: Describe decay in terms of S and P-waves decaying into K + K - S-wave P-wave S-P interf.
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SLAC DOE Review, Jun 7 200610 B 0 → KKK 0 : 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 K S region BABAR 230 MBB Belle 386 MBB (isospin) Belle’s method requires 1.7 times more data to have same error
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SLAC DOE Review, Jun 7 200611 Sin2 from KKK0 Dalitz plot of K + K - K S consists of K S (CP-odd) + S-wave (CP-even): -split sample into KS (CP-odd) and m(K + K - )>1.1 (CP-event) - treat any interference as syst. error KKK S In each mass region: K0K0 Belle BaBar “K + K - K 0 ” BaBar Belle K0SK0S K0LK0L BABAR, ~230MBB History plots of CP asymmetry measurements:
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SLAC DOE Review, Jun 7 200612 What More? Dalitz plot! Time-dependent Dalitz plot rate: Natural way to combine K 0 and high-mass KKK 0 decays Best way to treat interference effects Describe Dalitz plot amplitude in terms of (non)resonant components:
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SLAC DOE Review, Jun 7 200613 Understanding KKK 0 Dalitz plot D +,D s + reflections X(1500) non-res [BABAR,hep-ex/0507094] c0 ModeFraction (%) (1020)K S 15.4 3.4 0.6 X(1500)K S 5.2 2.2 0.9 (<8.3) 38.9 7.3 0.9 Non-resonant70.7 3.8 1.7 c0 K S 3.1 1.6 0.8 (<5.5) f 0 (980)K S 5.7 3.2 1.0 (<9.7) -First B 0 ->KKK S Dalitz plot analysis (time integrated) - Next: simultaneous fitting of entire Dalitz plot K 0 +KKK 0 and extraction of CPV parameters m(K + K - ) [GeV/c 2 ] m(K ± K S ) [GeV/c 2 ]
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SLAC DOE Review, Jun 7 200614 Other Progress in Penguins Improvements of BABAR analyses (using 230 M BB pairs): 1)Add submodes of existing channels: -K S -> - is only 34% of all K 0 decays -Add K L : ’K L, KKK L -Add K S -> : K S K S K S 2) Add channels with high background: - K S, K S - Total penguin average for BABAR: (sin2 ) ~ 0.09 - Stat. power from additional modes alone: (sin2 ) stat ~ 0.16
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SLAC DOE Review, Jun 7 200615 Performance for beta BABAR ~230 MBB Belle ~386 MBB Total error on sin2 as of Winter06 BABAR outperforms Belle even with less data - better analysis techniques - bigger boost, better PID
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SLAC DOE Review, Jun 7 200616 Summary and Plans All channels will be updated with 2006 dataset -BaBar error on sin2 ( ’K0) < 0.1 -BaBar+Belle combined penguin error ~0.04 SLAC contribution: - KKK S K S → (Dujmic), K S → (Thompson,Roodman) - K S, f 0 K S -> K S (Graham) - K S, ->3 (Suzuki) - K S (Allen, Roodman): - K : (Allen, Roodman), - Dalitz plot: K + K S K S, K + K + K - (Thompson,Dujmic,Roodman) - conveners of physics working group (Dujmic,Graham) beta Direct CPV
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