Determination of UT Angles

Transcription

1 CP Violation in treeominate processes an Determination of UT Angles Giancarlo Pirea INFN Roma La Sapienza On behalf of BaBar an Belle Collaborations 5th Rencontres u Vietnam Hanoi, August 6-12, 24 1

2 B-Physics in recent past (only 17 years ago) Measurement Of B oscillations. Foun large an m/γ 1 2

3 From Symmetric to Asymmetric B-Factory e - b b e + Symmetric (CESR) B travel 3µm _ e + e - Ψ(4s)->BB Asymmetric (booste): (First ieas in 1987) e - PEPII, KEKB < z> about 25 µm b e + 3 b

4 Measuring CP Violation in B ecays > The e + e - asymmetric way > Sin 2β: a precise measurement > Measuring angle α > Towar a γ etermination > Summary an Conclusions More etails in Parallel Sessions See also A.Satpathy on irect CP violation recent results. More than 4s effect foun!! 4

5 CP Violation an Stanar Moel CP violation generate by complex coupling constant Quark mixing matrix Cabibbo Kobayashi Maskawa matrix λ=sin(θ Cabibbo ) 3quark generations -> one non-removable phase λ /2 λ Aλ ( ρ iη ) Vu Vus Vub 2 2 ( ) V = V λ 1 λ /2 Aλ Vc Vcs Vcb 3 2 Vt Vts Vtb Aλ 1 ρ iη Aλ 1 Wolfenstein parameterization 5

6 The Triangles CKM matrix is unitary B system V u V * ub * * + VcVcb + VtVtb = α Phases-> angles α,β,γ or in this sie of Pacific φ2,φ1,an φ3 γ β CP violation proportional to triangle area: measure sies an angles inepenently 6

7 Constraints on the UT angles α γ new results on these B ecays: β φk s, η K s, K s π B ρ + ρ + B D [ K ] B π J/ ΨK * K α γ β Decay rates are small Nee high luminosity! 7

8 Belle Detector Aerogel TOF 3 layers Glass-RPC 8

9 BABAR Detector Quartz bar Cerenkov Detector (DIRC) 1.5 T solenoi Electromagnetic Calorimeter e + (3.1 GeV) e - (9 GeV) Drift Chamber Instrumente Flux Return RPC bakelite soon LST 5 layers Silicon Vertex Tracker 9

10 Experimental Technique 1

11 B Reconstruction at Υ(4S) e + e Υ( 4S) BB Kinematic signature for B ecays: m ES m ES E = = E *2 beam * * E B E beam p *2 B Typical resolutions: σ(m ES ) 2.5 MeV σ( E) 15-3 MeV measure in Υ(4S) rest frame signal siebans E B signal: E=, m ES = m B Define 2 regions in E, m ES plane: - Signal region - Sieban region m ES (GeV) 11

12 Current Luminosities Tot fb -1 =.53 ab -1!! Belle 15fb -1 /month L= cm -2 s -1 22fb -1 /month L= cm -2 s -1 12

13 General CP Formalism Decay istributions f + (f - ) when tag = B (B ) Γ Γ t fcp, ± ( t) = e [1± Sf sin m m cos ] CP t Cf m CP t 4 Asymmetry A ( t) = C cos( m t) S sin( m t) CP parameter CP eigenvalue Wolfenstein convention f f f CP CP CP q Af CP λf = η CP fcp p A e 2i β f CP from mixing Amplitue ratio Decay B B C S J / Ψ, K π π f CP f CP 2 1 λf CP = λf CP 2Imλf CP = λ Arg( A/ A) (-2γ) f CP λ 1 1 For single amplitue = = Imλ phase sin2β sin2α 13 f CP

14 Measurements of β See also N.Barlow talk B b c c s b c c s J/Ψ K Charmonium K Penguin an tree have the same weak phase B b c c b b D (*) D (*) an J/Ψπ c c s s s D (*)+ D ( ) φ K Penguin an tree have ifferent weak phases: asymmetry not necessarily = sin2β φk an η ( ) K Mostly penguin. In principle measures sin2β, but sensitive 14 to new physics

15 Charmonium Κ CP=-1 CP=+1 Sin2β= Events with K S Events with K L 15

16 Unitarity Triangle Fit CKMfitter A.Hoecker et al (sin 2β) =.736 ±.49 + WA (stat syst) 16

17 charmonium Do we start to see effects in the penguin moes? (see next talk) penguin sin2β Heavy Flavor 17 Average Group

18 Measurements of α See also M.Pierini talk B b * V ub A = e iγ u u T b + e iβ V t P u u π + π π + π, ρ + π, π + π π,ρρ Penguin an tree have ifferent weak phases. A λ = = e iγ T + e iβ P q A 2iα p A α = π ( β + γ ) = λe Strong phases ifferent 2 eff α = 2α + κ ππ π + π, ρ + π,ρ + ρ require isospin analysis 18

19 Isospin analysis A( B + π + π = 1/ 2 A( B π π + ) + A( B π π ) Asymmetry in π + π - sin2α eff = sin(2α+κ ππ ) Isospin analysis etermines κ ππ. Nees B π π an B π π. Or, use π π rate to boun κ ππ. Small π π rate small κ ππ. 19

20 2 π + π CP Asymmetries S C BaBar: 113 fb -1 Belle: 14 fb -1 ) ) ( ( ) ) ( ( ) ) ( ( ) ) ( ( = π π π π π π π π t B N t B N t B N t B N

21 Comparison of A ππ =-C ππ ans ππ A ππ =-C ππ 5.2σ CPV Belle ~2σ iscrepancy Physical boun BABAR 2σ CPV S ππ Difference still at ~2.σ level 21

22 π π has now been seen events BR = ( ) σ significance events BR = ( ) σ significance 22

23 but we on t like it! Penguin pollution Too small for isospin analysis with the present samples Too large for useful boun e.g. Grossmann-Quinn boun 2 BR( B / B π π ) sin ( αeff α) < + + BR( B π π ) Gives α eff - α < 47 o 9% C.L. Worl average 23

24 B ρρ: it gets better. Foun almost fully longituinally polarize B ρ ρ is very small! Grossman-Quinn boun is useful α eff - α < 16 o (13 o 9% (68.3%) C.L. Belle also has similar measurements 24

25 B ρ + ρ S = 19. ±.33 ± 11. C = 23. ±.24 ± 14. long (stat) (syst) long (stat) (syst) BF( B ρ ρ ) < (9% CL) B tag BABAR AR 113 fb 1 B tag α = (96 ± 1 ± 4 ± 13 ) stat syst peng o New: Winter 4 Belle α = ± 13( peng) o Isospin analysis: interference, NR contributions, I=1 25 amplitues neglecte

26 B πππ : Full Dalitz Analysis Snyer-Quinn Metho Extract α an the strong phases using the interference between B π + π π amplitues A(B ρ + π ) A + = T + e iα P + A(B ρ π + ) A + = T + e iα P + A(B ρ π ) A = T e iα P π + π π amplitue parametrization: A 3π = f + A + + f A + + f A A 3π = f + A + + f A + + f A The f +,, are relativistic Breit-Wigner form factors ρ + π ρ π ρ π + σ α ~25 in 113 fb -1 without ambiguity (BaBar estimate) 26

27 α status an prospects Too much penguin pollution in B ππ Observe B π π but - More statistics neee for Isospin analysis Too large for useful α eff - α boun Situation looks better in B ρρ Longituinally polarize, CP eigenstate Very small B ρ ρ inicate small penguin pollution Other approaches also in the works. 27

28 Towar a γ etermination The challenge: irectly measure the b u phase (γ) relative to the b c phase (). Most straightforwar tool: B DK See also M.Rama talk These amplitues interfere for D final states that both D an D can ecay to. 28

29 γ from B DK Relative size of B ecay amplitues Fcs is an unknown colorsuppression factor. Expecte to be in the range [.2,.5]. Ru is the left sie of the Unitarity Triangle (~.4). Want r b to be large to get more interference. 29

30 γ from B DK: GLW metho Gronau, Lonon, an Wyler: use D ecays to CP eigenstates. Equal D an D ecay amplitues by construction. CP even: π + π,k + K CP o: K s π, K s ρ 4 equations, 3 unknown δ b = strong phase iff 3

31 DK GLW Metho: Belle Analysis Dπ D->Kπ D K + K -, π + π D K S π, K s φ, K S ω, K S η, K S η O(9M) BB pairs 31

32 + D K π,... BABAR AR GLW: BaBar Analysis 81 fb CP + B D K Comparing BaBar vs Belle D DK K K D π, π π + + R + BABAR [81fb -1 ] 1.6±.19±.6 Belle [78 fb -1 ] 1.21±.25±.1 A CP+.7±.17±.6.6±.19±.4 R - * 1.41±.27±.15 DK D π A CP- *.19±.17±.5 *Coming soon Goo agreement within large errors 32

33 γ from B DK: ADS metho Atwoo, Dunietz, an Soni: equalize the interfering amplitues favore suppresse suppresse favore 2 r = BR D BR( D + ( ) K K π π ) δ charm strong phase GLW ADS Complementary to GLW 33

34 ADS: B (*) K D 19 fb-1 r b Signal consistent with zero N= R r b ADS <.26 <.22 R ADS 9%C.L. r b 34

35 A promising metho Giri, Grossman,Soffer,Zupan+ Belle Interference in the Dalitz plot of B - D /D K - with D /D K S π + π. AB ( ) B - D K - B - D K i( δ γ ) 2 2 f ( M, M + ) re B f M+ M 2 2 i( δ+ γ ) 2 2 f( M+, M ) rb e f ( M, M+ B + D K + B + D K + = + (, ) + A( B ) = + ) M ± =invariant mass(k s π ± ) f =Dalitz D ecay amplitue Both interfering D amplitues Cabibbo-favore No CP violation in D assume 35

36 Determining the D ->K s π + π amplitue High statistics D* - D π from e + e - cc process f = sum of resonances some moel epenency 36

37 B D D K ± + D D K s π π M 2 - M 2 + M 2 + M 2 - Φ = ( ± ) 1σ rb = In agreement with Babar ( ) combining with D* sample 37

38 Fitting All Together (GLW+ADS+DALITZ) r γ Probability Density function courtesy of 68% 95% Drawn into the ρ η plane γ η r r b ρ 38

39 Summary an Conclusions sin2β in charmonium moes is now a precision measurement sin2β=.736±.49 worl av. Hints of iscrepancy between charmonium an penguin moes? (see next talk) First measurement of α (with assumptions): α = 96 o ± 1 o (stat.) ± 4 o (syst.) ± 13 o (penguin) Very preliminary, neglecting interference, NR contribution New techniques to measure γ being evelope -γ etermination looks ifficult -nee huge statistics 39

40 Back-up Slies 4

41 Inputs: γ = 6 o δ B = o δ D =25 o 5 fb -1 Some extrapolations: goo scenario r B =.1 r B =.2 r B =.3 γ Green: ADS only Blue: GLW only Re: Combine 41

42 Measurements of γ Contributions from b u transitions bring a epenence of CPV from γ Measure γ in irect CP asymmetries in charge B ecay rates Measure 2β+γ with CPV in mixing Two cases B A 1 ~λ 2 c b u c π + D ( ) A 2 ~λ 4 c B b c u D ( ) π + See M.Rama talk sin2β+γ: A 2 oubly cabibbo suppresse B + A 1 ~λ 3 c b u s u c u Κ ( )+ D ( ) A 2 ~λ 3 c B + b u u c s u D ( ) Κ ( )+ sinγ: A 2 colour suppresse 42

43 Favore amplitue B b VV cb * u W + = A Measuring γ in B->D(*)π c u π + ( ) * D Suppresse amplitue through b u transition B b W u VV e = Ae e * iδ iγ iδ ub c r(*) c (*) D π + (*) + (*) AB ( D π ) ( π ) r(*) =.2 (*) + rd AB ( D π ) C.L. Sin(2β+γ)>.76@ 9.% C.L. B CKM angle mixin g B Strong phase ifference f 43

44 ρ η constraints from D (*) π B system Eviences of from D (*) Κ ( ) BaBar 44