Download presentation
Presentation is loading. Please wait.
Published byChristina Nicholson Modified over 8 years ago
1
Measurements of 1 / Flavor Physics and CP Violation 2010, May 25, 2010, Torino, Italy, K. Sumisawa (KEK)
2
V* td __ t d t b b d _ w w B0B0 B0B0 _ V* td =| V td |e i1i1 pqpq ~e +i2 1 mixing induced CP violation Time-dependent CP Violation in B 0 decays KM ansatz: CPV is due to a complex phase in the quark mixing matrix B0B0 B0B0 f CP B0B0 B0B0 A A = A A qpqp ~e -i2 1 B-B mixing _ Unitarity Triangle 1 2 3
3
Time-dependent CP Violation in B 0 decays Mixing-induced CPV Direct CPV e.g. for B 0 J/ Ks S = - CP sin2 1 = +sin2 1 A ~ 0 ( CP : CP eigenvalue 1) e.g. for B 0 J/ Ks S = - CP sin2 1 = +sin2 1 A ~ 0 ( CP : CP eigenvalue 1) B0B0 A f CP B0B0 A tt Decay time difference between B meson pairs We can measure CPV (asym.) as a function of proper time diff ( t). (A= -C)
4
Principle of Measurement in B-factories Reconstruct B f CP ( b c ) decays Measure proper-time difference: t Determine flavor of B tag Evaluate CP asymmetry from t and flavor of B tag ee ee B CP zz B tag (4 S ) ~ 0.43(Belle) ~0.56(BABAR) f CP ( b c ) z c B ~ 200 m(Belle) ~ 250 m(BABAR) Flavor tag ( ) z c t ≈
5
8 3.5GeV 2.1×10 34 cm -2 s -1 2 B-factories PEP-II 9GeV(e - ),3.1GeV(e + ) 1.2 10 34 cm -1 s -1 BABAR Detector 4 lyr.
6
Success of the B-factories Stopped in April 2008
7
sin2 1 with charmonium K 0 modes N sig =7482 Purity=97% N sig =6512 Purity=59% N sig =8733 Purity=93% N sig =5813 Purity=56% E B - E CM /2 535MBB 465MBB _ _
8
sin2 1 with charmonium K 0 modes sin2 1 =0.642±0.031±0.017 A f =0.018±0.021±0.014 PRL98,031802(2007) sin2 1 =0.687±0.028±0.012 A f =-0.024±0.020±0.016 PRD79,072009(2009) (cc)K S J/ K L
9
error in 1 < 1 but ambiguities exist. sin2 1 1 agreement between two experiments
10
B 0 D[K S + - ]h 0 (h 0 = 0, , ) _ Time dependent Dalitz analysis gives sin2 1 and cos2 1 cos2 1 >0 at 86% C.L cos2 1 >0 at 98.3% C.L. smaller 1 (<45 ) solution is favored. consistent with b ccs sin2 1 describe Dalitz variables. _
11
constraint for 1 / other measurement using J/ K* 0 (K* 0 Ks 0 ) D* + D* - Ks can also contribute.
12
b ccd J/ 0 : constrain penguin contribution in Golden mode(J/ K 0 ) without model dependence. D ( * )+ D ( * )- : penguin contribution is expected to be small. tree + (penguin)
13
b ccd J/ 0 : constrain penguin contribution in Golden mode(J/ K 0 ) without model dependence. D ( * )+ D ( * )- : penguin contribution is expected to be small. Belle A=-C=0.91 0.23 0.06 (3.2 significance A≠0)
14
14 b sqq TCPV _ d b _ c c s d _ w B0B0 J/ K0K0 d b _ _ s s s d _ gt B0B0 K0K0 , ’... w Extra CPV phase from New Physics Time-Dependent CP asymmetry in B 0 decays S =sin2 1 A ~ 0 S =sin2 1 eff A ~ 0 Many two-body and quasi-two body analyses have been done. Since → K + K -, f 0 → K + K - and non-resonant contributions overlap invariant mass(as do 0 → + - and f 0 → + - ), recently time-dependent Dalitz analyses have been performed in three-body decays such as B 0 → (K + K - )K S and B 0 → ( + - )K S.
15
Interferences in B decays with K + K - Ks final state B0B0 K S CP= -1 A1A1 K+K-KSK+K-KS f 0 (980)K S CP= 1 A2A2 ANAN Non-resonant CP=+0.86±0.20 K S f 0 (980)K S Non-resonant Dalitz-plot ⇒ distinguish the intermediate states considering interferences Opposite CP eigenvalue from Ks ⇒ State-by-state CP measurement Dalitz-plot
16
Time-dependence of Dalitz plot in B 0 →K + K - Ks B0B0 K S A A K+K-KSK+K-KS f 0 (980)K S B0B0 CP asymmetry ( 1,eff, A CP ) of B K S using Time-dependent Dalitz plot analysis in B K + K - Ks B0B0 A K+K-KSK+K-KS B0B0 A c.f. Time-dependence Interference in B 0 B 0 ( 1,eff )+ intermediate states (Dalitz phase) Time-dependenceDalitz-plot
17
updated Belle result (B 0 K + K - Ks ) Decay amplitude resonanceForm factorSpinCP eigenvalue f 0 (980)Flatté01 (1020) RBW1 f x (1500)RBW01 c0 RBW01 ( KsK - ) K + exp(- s - ) 01 ( KsK + ) K - exp(- s + ) 01 ( K + K - )Ks exp(- s 0 ) 01 RBW: Relativistic Breit Wigner 19 free parameters 12: isobar model 6: CPV parameters. 1: for NR Belle 657MBB to be submitted to PRD.
18
Multiple solution 4 preferable solutions External information from B 0 → + - Ks f 0 (980) B.F.(f 0 (980)→ + - )/B.F.(f 0 (980)→K + K - ) and compare with PDG solutions with low f 0 (980)Ks fraction preferred f x (1500) If f x (1500)=f 0 (1500) for both decays B.F.(f 0 (1500)→ + - )/B.F.(f 0 (1500)→ K + K - ) and compare with PDG solutions with low f x (1500)Ks fraction preferred Decay mode fractions Solution 1 preferred.
19
fit result (Dalitz plot) (1020) c0 f x (1500) D veto J/ veto background Solution 1
20
fit result ( t plot) proper time distribution and raw asymmetry plot in mass region Belle 657MBB to be submitted to PRD. background Solution 1 the third error: Dalitz plot model uncertainty SM expectation
21
(7.7 7.7 0.9) (8.5 7.5 1.8) BABAR K + K - Ks result whole regionlow mass region BABAR 465MBB arXiv:0808.0700
22
average in B Ks, B f 0 (980) Ks Consistent with the Standard Model prediction at current sensitivity 1(b ccs) = (21.0 ± 0.9)° (7.7 7.7 0.9) (8.5 7.5 1.8)
23
result using + - Ks Belle 657MBB PRD79(2009) 072004BABAR 383MBB PRD80(2009) 112001
24
Compilation of effective sin2 1 Still precision is statistically dominated. ↓ To obtain sensitivity in effective sin2 1 of O(10 -2 ), we need O(10ab -1 ) of integrated luminosity.
25
Summary 1 / = (21.1 0.9) in B-factories sin2 1 from b ccs modes. resolve the quadratic ambiguity by measuring cos2 1 with Dalitz analysis, etc. penguin modes are good probes of new physics. We need more data. Belle is now updating its result with the full data sample. J/ K 0 full data: 535M 771MBB (factor 1.44) improved tracking software: 20% gain for J/ Ks yield : factor 1.61 (2S)Ks, c1 Ks, c Ks, and combined analysis last update with150MBB (657MBB for (2S)Ks) (statistical error for sin2 1 )~0.02 etc.. _ __
26
backup
27
27 background Combined result:
28
Resonances considered in the KsKK signal model 28/38
29
29/38 Signal PDF = 1. Dalitz amplitude and phases 2. CP-violating amplitude and phases ( Ks, f 0 Ks, others) 3. Kinematics (Dalitz plot) for NR Decay amplitude Time-dependence Dalitz-plot × B0:B0: B0:B0: q 2 q ⇒ 19 fit parameters
30
30/38 Event selection B 0 →KsK + K - reconstruction Ks selection K ± selection by PID (K/ ) Continuum suppression Efficiency: ~16% Unbinned ML fit to E and M bc distributions B 0 →KsK + K - 1176±51evts. Purity~50% Background Continuum ~47% Other B decays ~3% Event-by-event signal probability f sig ( E, M bc ) for CP measurement Reconstructed B 0 →KsK + K - candidates Signal Continuum M bc EEEE Other B decays Time-dependent Dalitz plot fit to the selected B 0 KsK + K - candidates.
31
plots for K + K - Ks signal background mass region A CP ( t) raw asymmetry plot in mass region Belle 657MBB ICHEP2008 preliminary
32
BABAR K + K - Ks result whole regionlow mass region BABAR 465MBB arXiv:0808.0700 (7.7 7.7 0.9) (8.5 7.5 1.8) (8.? 8.?) (197 11)
Similar presentations
© 2025 SlidePlayer.com. Inc.
All rights reserved.