CKM phase and CP Violation in B Decays

Transcription

1 CKM phase and CP Violation in B Decays David Brown Lawrence Berkeley National Lab BaBar Collaboration August 14, 2007 Daegu, Korea

2 Talk Outline Review of CPV in the B system Results on the CKM unitarity angle β=φ 1 Results on the CKM unitarity angle α=φ 2 Results on the CKM unitarity angle γ=φ 3 Results on the B s phase angle φ s Results on Direct CPV Conclusions I will concentrate on (some) New Results 2

3 Quark-Sector Flavor in the SM 3 known generations of quark doublets (u,d) (c,s) (t,b), EM charge (2/3, -1/3) Origin of families unknown in SM Only the charged-current EW interaction can change flavor in the SM EW eigenstates aren t mass eigenstates Only SM connection between generations! V CKM 3

4 The CKM matrix Relates EW flavor and quark mass eigenstates No prediction of values within SM 3 generations, Unitarity 3 rotations, 1 phase Non-zero phase implies CPV in flavor transitions New Physics (NP) with non-sm flavor couplings would make the CKM description incomplete Eg: 4th generation, SUSY, Wolfenstein parameterization V CKM = V ud V us V ub V cd V cs V cb V td V ts V tb 1-λ 2 λ A λ 3 (ρ-iη) = -λ 1- λ 2 /2 A λ 2 + O(λ 4 ) Aλ 3 (1- ρ-iη) -A λ λ 0.23, A 0.8, ρ 0.2, η 0.4

5 The Unitarity Triangle(s) Graphical expression of unitarity condition(s) 1 triangle has roughly equal-length sides CKM Unitarity violation would imply New Physics Test SM + CKM by over-constraining angles and sides ( ρ, η) I α (0,0) γ ρ-iη % " = # 3 = arg $ V V * ( ud ub ' * * & V cd V cb ) % " = # 2 = arg $ V V * ( td tb ' * * & V ud V ub ) % " = # 1 = arg $ V * cdv cb ( ' * * & V td V tb ) β (1,0) 5 R " + i# $ % V * udv ub * V cd V cb ( ) = " + i# + O & 2

6 Consequences of CPV CPV can occur when multiple B F amplitudes interfere CPV in decay (direct CPV) CPV in mixing (original CPV seen in K S, K L ) Very small for B system (exp. limit <10-2, predicted ~10-3 in SM) CPV in mixing + decay (indirect CPV) B system uniquely situated for CPV studies Mixing, long lifetime, large production X-section, rich decay set, heavy quarks theoretically accessible, I Δ EW 1 EW 2 S 1 S 2 Direct CPV CP R S EW 1 1 S 2 Δ Δ B 0 and B ± I EW 2 R Mixing+Decay CPV F CP A f CP B 0 B 0 decay A F e -2iβ Δ 0 A F decay 6

7 Detecting Indirect CPV in B-decays A CP ("t) = N(B 0 ("t) # f CP ) $ N(B 0 ("t) # f CP ) N(B 0 ("t) # f CP ) + N(B 0 ("t) # f CP ) = S f sin("m "t) $ C f cos("m "t) " f # A f A f e $2i% S f = 2"(# f ) 2 C f = 1" # f 2 1+ # f 1+ # f 2 B-factories e - ϒ(4S) B 0 (b) e - K - Coherent evolution e + µ + π + mixing Δz βγcδt µ - Flavor tagging Q 30% at B-factories few % at Tevatron π - B f CP exclusive reconstruction ε~10% 7

8 The B-factories Asymmetric e + e - colliders make boosted ϒ(4S) βγcτ B ~200 µm in the lab frame General-purpose detectors Tracking EM calorimetery, muon system, PID, BaBar/PEP-II Total Sample 450 fb -1 KEK-B/Belle Total Sample 700 fb -1 Data sets have increased ~10% in the last year Many new results from data backlog! Tevatron Run2 results on 1fb -1 coming out now 8

9 Beta B 0 B 0 η ( ρ, η) α % " = # = arg $ V cd V * cb 1 ' V V * & td tb ( * ) (0,0) γ β (1,0) ρ 9

10 β B 0 charmonium K 0 : b c cs J /","',# c,$ c " gold = e #i$ f 2% η f = CP eigenvalue K S,K L = -1(K S ),+1(K L ) No EW phase SM decay dominated by a single tree diagram Leading order (Tree) diagram has no weak phase asymmetry directly measures β Higher-order diagrams are smaller by factor ~O( ) most have same EW phase BF 10-3 (color suppressed) SM expectation: S = -η f sin2β, C 0 10

11 β B 0 charmonium K 0 : b c cs N B B = 535M N sig = 7484±87 background J /"K L 0 N B B = 383M N sig = 4748 Purity=55% PRL 98, (2007) hep-ex/ Easily reconstructed final states Charmonium l + l - has high efficiency, low background K S π + π - easily recognized in tracking detectors Strong kinematic variables separate B from background M B (GeV/c 2 ) background M B constrained to known beam energies to improve resolution ΔE E B -E beam is an independent kinematic variable 11

12 β sin2β in B 0 charmonium K 0 : b c cs J/ψK S N B B = 383M N B B = 535M B 0 tags B 0 tags J/ψK L background BaBar Preliminary (hep-ex/ ) S = ± ± C = ± ± Δt (ps) PRL 98, (2007) η f Δt (ps) S = ± ± C = ± ± 0.014

13 β β from B 0 charmonium K 0 : b c cs S f = sin2β 95%CL contours Sin2β=0.678±0.026 New world average 13 Sets the gold standard for CPV measurements new 2-fold ambiguity resolved by several cos2β, β measurements B 0 D 0 3-body h0 Dalitz Analysis (BaBar) B 0 K S π + π - Dalitz Analysis (BaBar) B 0 K S K + K - Dalitz Analysis (BaBar) + older results on B 0 J/ψK*,

14 β B 0 B 0 D + D - : b c cd D - D + B 0 NP particle can enter in loop D - D + Two decay amplitudes interfere b c tree diagram with S = -sin2β b d penguin diagram with S ~ 0 Penguin is expected to be small ~2-10% (PRD 61, , 2001) Larger backgrounds Standard Model predicts: S =! sin 2" C ~ < 10% Y. Grossman and M. Worah, Phys. Lett. B 395, 241 (1997) 14

15 β S and C in B 0 D + D - : b c cd B 0 tags C (0,0) B 0 tags N B B = 535M N sig =128±14 background N B B = 383M N sig =131±14 Belle claims evidence for direct CP violation at 3.2 σ S C CP (B 0 D + D - ) = ± 023 ± 0.06 C CP (B 0 D + D - ) = +0.11± 022 ± 0.07 hep-ex/ Agreement on C has CL=0.003 >3.0σ discrepancy 15 PRL 98,221802(2007) BELLE-CONF-0762 New Belle Result: A CP (B + D + D 0 ) = 0.01 ± 0.08 ± 0.02 Preliminary

16 β CPV in B 0 D* + D* - : b c cd Same diagram as B 0 D + D -,but Vector-Vector final state η f (CP) depends on helicity, analyzed using D* decay angles BaBar preliminary N B B = 383M N sig =617±33 background 16 hep-ex/ R " = 0.143± ± S = #0.66 ± 0.19 ± 0.04 C = #0.02 ± 0.11 ± 0.02

17 β S and C in b c cd -S f C f sin2β Silver modes: generally good agreement with golden mode S= -sin2β, C=0 17

18 β Purely Penguin decays: b s qq SM New Physics s q q SUSY, s q q No tree-level contributions New Physics can enter at equal order as SM SM predicts same EW phase as b cw - Comparison with charmonium sin2β provides a direct test for NP Many accessible modes NP might couple to some or all More challenging experimentally BF ~10-5, large backgrounds from continuum 18

19 β B 0 K S π 0 π 0 :b s qq (Spherical) (Jet-like) LR>0.9 LR>0.9 N sig = 307±32 LR>0.9, good tag Δt (ps) 19 LR B 0 tags B 0 tags M B (GeV/c 2 ) ΔE(GeV) N B B = 657M S =+0.43 ± 0.49 ± 0.09 C=+0.17 ± 0.24 ± 0.06 Δt (ps) Preliminary BELLE-CONF σ from the SM expectation S= -sin2β

20 β B 0 K S π + π - :b s qq Measure TDCPA at each point on the Dalitz plot Include interference between π + π -, K S π ± resonances ρ 0, f 0,K*, Supersedes previous results on B 0 K S ρ 0,K S f 0 + Direct CPV in B 0 K* + π, relative phases χ 2 χ 2 B 0 K S f 0 (980) B 0 K S ρ 0 (770) 2β eff hep-ex/???? 2β eff B 0 " K S f 0 (980) : 2# eff = $20.2 ± 5.1± 7.8 o B 0 " K S % 0 (770) : 2# eff = $17.4 ± 5.3± 5.9 o B 0 " K * (892)& : A CP = $0.18 ± 0.1± 0.03± σ > 2β from charmonium 2-fold β ambiguity (partially) resolved 20

21 β sin2β in b s qq Penguins S f = -sin2β eff sin2β sin2" eff = 0.67 ± % CL for the average New naïve HFAG average <1σ from the naïve golden mode sin2β value 21 New/Updated BaBar/Belle Result

22 Alpha % " = # 2 = arg $ V V * td tb ' * & V ud V ub ( ρ, η) η α γ β (0,0) (1,0) ( * In principle measurable using ) any b u dominated B 0 f CP Very rare decays! BF~10-6 ρ In practice, penguin modes have similar magnitude, different EW phase extracting α is a challenge! 22

23 α B 0 π + π - : b u ud B 0 tags B 0 tags B 0 tags B 0 tags N B B = 383M N sig = 1139±39 N B B = 535M N sig = 1464±65 PRD 75 (2007) PRL 98, (2007) S "" = #0.60 ± 0.11± 0.03 (5.2$) S "" = #0.61± 0.10 ± 0.04 C "" = #0.21± 0.09 ± 0.02 (2.2$) C "" = #0.55 ± 0.08 ± 0.05 (5.5$) 2.1σ tension in Cππ 23

24 α Extracting α from B 0 π + π - CPV well established Problem: extract α from α eff Solution: Isospin Measure isospin-related modes Rates and C/A CP (if possible) Adds another discrete ambiguity! M. Gronau and D. London, Phys Rev. Lett. 65, 3381 (1990) ± 11 BR(B 0 π 0 π 0 ) = (1.47 ± 0.25 ± 0.12) 10-6 C(B 0 π 0 π 0 ) = ± 0.35 ± 0.05 BR(B ± π ± π 0 ) = (5.02 ± 0.46 ± 0.29) 10-6 A(B ± π ± π 0 ) = 0.03 ± 0.08 ± 0.01 hep-ex:

25 α Large signal observed significant background B 0 a 1+ π : b u ud First TDCPV analysis of a 1+ π N B B = 383M B 0 tags background B 0 K 1+ π N sig = 608 ± 53 PRL. 97, (2006) B 0 tags M B (GeV/c 2 ) PRL hep-ex/ N B B = 535M N sig = 654 ± 70 M B (GeV/c 2 ) αeff = 78.6 ±7.3 use SU(3) to relate states BF B 0 K 1+ π BF and A CP in B 0 a 1- Κ + Next step: constrain Δα

26 α B 0 (ρρ) 0 : b u ud Vector+Vector final state Analyze helicity to separate CP admixture as in B 0 D* + D* - Use Isospin triangle to constrain Δα as in ππ N B B = 383M TDCPV in ρ + ρ N B B = 535M N sig =729 ± 60 hep-ex/ Δt (ps) C = 0.01 ± 0.15 ± 0.06 S = ± 0.20 fl = ± PRD76, (R) (2007) C = "0.16 ± 0.21± 0.07 S = ± 0.30 ± 0.07 Δt (ps)

27 α The critical side: B 0 ρ 0 ρ 0 N B B = 427M N B B = 520M BaBar Preliminary N sig = 85 ± 27 ± 17 L sig / L sum signal N sig =34±16 M B GeV/c 2 M ππ GeV/c 2 B " = (0.9 ± " 0 #0.4 ) $10 #6 <1.6 $10 f L = 0.6 ± 0.2 BELLE-CONF-0747 Preliminary hep-ex/ Δt (ps) B = (0.84 ± 0.29 ± 0.17) "10 #6 f L = 0.70 ± 0.14 ± 0.05 S 00 L = 0.5 ± 0.9 ± 0.2 C 00 L = 0.4 ± 0.9 ± 0.2 First TDCPV analysis of ρ 0 ρ 0! Preliminary

28 α Constraining α using b u ud B 0 (ρρ) 0 BaBar Preliminary " WA = 87.7 ± α

29 % " = # 3 = arg $ V * udv ub ( ' * * & V cd V cb ) Gamma B - D 0 K - K - ( ρ, η) η α γ (0,0) 29 β B - B +,B - rate asymmetry (DCPV) is sensitive to γ. The problem: How to distinguish EW phase from strong phase? (1,0) ρ Can also measure 2β+γ via TDCPV in B 0 D + π -,+ D 0

30 γ γ from B ± D 0 K ± Three Answers D 0 decays to 2-body CP eigenstates (K + K -, π + π -, ) GLW large + unknown asymmetry in B +,B - BFs D 0 decays to non-cp eigenstates (K + π -, K + π - π 0, ) ADS Better match in rates (Cabbio suppression enhances interference) D 0 decays to 3-body (K 0 S π+ π - ) GGSZ Uses (~known) variation of resonance strong phase across Dalitz plot Requires detailed model of resonant substructure All methods have (varying) weakness due to unknown or under-constrained parameters Constrain γ by combining results from all methods GLW Gronau, London (1991),Gronau, Wyler (1990) ADS Atwood, Danietz, Soni (1997) GGSZ Giri, Grossman, Soffer, Zupan (2003) 30

31 γ Combined constraint on γ γ = 88 ± 16 Includes a new preliminary result: B ± D 0 K ± GLW (BaBar) γ 31

32 The Unitarity Triangle: angles only 32

33 The Unitarity Triangle: all constraints A consistent picture across a huge array of measurements 33

34 Bs J/ψφ (φs): b c cs Same quark decay as B0 charmonium K0 Bs mixing goes as Vts ~ no CPV phase as in Bd mixing Hep-ph/ SM prediction of φs = 4.2 ± 1.4X10-3 Simultaneous fit to φs, ΔΓs #0.39 " s = #0.70 Consistent with SM! 34

35 Direct CPV in charmless B Decays K + ρ 0 3.0σ ηk* 0 3.8σ ηk + 3.0σ K + π - ~8σ Isospin analogs A Kπ (B + K 0 π + )=0.009 ± A Kπ (B + K + π 0 )=0.050 ± A Kπ (B d )= ± (WA) Effect from EW penguins? 35

36 Direct CPV in B s Decays A Kπ (B d )= ± ± σ significance A Kπ (B s )=0.39 ± 0.15 ± σ significance Comparing A Kπ (B d, B s ) 36 Consistent with SM prediction 1.0 H.J.Lipkin, Phys. Lett. B 621, 126 (2005)

37 37 Conclusions Standard Model CKM CPV is well established Confirmed by many analyses, several experiments Unitarity angle precision continues to improve Sin2β is still statistics limited! New, innovative techniques are still being developed CPV provides a unique window on the SM Data constrain the unsolved problems of flavor/ generation mixing, matter-anti-matter asymmetry The existing B-factories will soon be turned off BaBar,Belle complete in ~2008,Tevatron in ~2009 Look for final analyses in ! Future flavor physics depends on future facilities LHCB, super-b, super-belle,

38 BACKUP

39 The B-factories Belle KEK-B PEP-II 39

40 Datasets Pep-II BaBar Total 450 fb -1 KEK-B BELLE Total = 700 fb -1 40

41 β B 0 J/ψπ 0 : b c cd NP particle can enter in loop Enhanced sensitivity to higher-order (penguin) diagrams Cross-check on assumption that C gold 0 M.Ciuchini,M.PieriniandL.Silvestrini,Phys.Rev.Lett95,221804(2005) N B B = 535M 290 J/ψπ 0 candidates Purity=88±7% hep-ex/ (submitted to PRD.RC) C S= 0.65 ± 0.21± 0.05 C= ± 0.16 ± 0.05 (0,0) 41 M B (GeV/c 2 ) S

42 β B 0 D* +- D -+ : b c cd Final state not a CP eigenstate Could show time-integrated charge asymmetry TDCPA modified by strong phase difference (S +- S -+, C +- C -+ ) If penguin contribution is zero, C -+ = -C +-, β eff =β If S -+ = -S +-,No CPV sin(2β eff ) = 0 42

43 β S and C in B 0 D* +- D -+ : b c cd B 0 D *+ D - N B B = 383M B 0 D *- D ± 19 signal events 219 ± 18 signal events Hep-ex/ Time-integrated asymmetry consistent with 0 sin(2β) cosδ 4σ No significant direct CPV 43

44 β B 0 D 0 3-bodyh 0 : b c ud D 0 K S π + π - = coherent ensemble of quasi 2-body decays (Known) variation of strong phase over Dalitz plot allows extraction of strong and weak phase differences! Must measure TDCPA at all points in the Dalitz plot 2-fold ambiguity on β can (in principle) be resolved N B B = 383M BaBar Preliminary (update) N sig = 335 ± 32 hep-ex/???? 44

45 β B 0 D 0 3-bodyh 0 Dalitz Analysis : b c ud B 0 tagged BaBar Preliminary h 0 = π 0,η ( ' ),ω B 0 tagged K* + K* - ρ 0 sin2" = 0.29 ± 0.34 Asymmetry cos2" = 0.42 ± 0.49 # =1.01± 0.08 cos2β>0 at 84% CL 45

46 β B 0 K S K + K - :b s qq Measure TDCPA at each point on the Dalitz plot Includes interference between K + K -, K S K ± resonances hep-ex/ A CP = ± ± β eff = ± ± rad 4.8σ significance 46

47 β B 0 D 0 CPh 0 :b c ud N B B = 383M N sig =335±32 b c ud tree dominates b u cd suppressed ~1/50 D 0 CP D 0 KK, K S ω also D* 0 D 0 CPπ 0 h 0 π 0, ω, η SM predicts S=-sin2β, C 0 47 background hep-ex/ S = "0.56 ± 0.23 ± 0.05 C = "0.23± 0.16 ± 0.04 First TDCPA in these modes!

48 β B 0 K S K S :b d ss R. Fleischer and S. Recksiegel, Eur.Phys.J.C38: ,2004 Entries/2.5ps N B B = 657M K 0 N signal =33±6 B 0 B V 0 tags td B 0 tags K 0 d EW decay phase cancels mixing phase No CPV expected! C 48 (0,0) BaBar result PRL 97 (2006) S Raw Asymmetry background S = ± 0.77 ± 0.08 C = ± 0.38 ± 0.05 SM expectation:s 0,C 0 BELLE-CONF-0723 A.K.Giri and R.Mohanta, JHEP,11,084(2004)

49 α Constraining Δα in B a 1 π via SU(3) No phase-space overlap between a 1+, a 1-, and a 1 0 Can use SU(3) to relate p K and a 1 K 1A Necessary BFs are measured, Δα not yet computed K1 A = cos! K1(1400) + sin! K1(1270) B 0 K 1+ π B 0 a 1- Κ + Gronau & Zupan, Phys. Rev. D73, (2006) BaBar Preliminary M Kππ GeV/c 2 BF(B 0 K 1+ (1270)π - ) = 12.0 ± X10-6 BF(B 0 K 1+ (1400)π - ) = 16.7 ± X10-6 M B GeV/c 2 BF(B 0 a 1 - K + ) BF(a 1- π + π - π - ) = 8.2 ± 1.5 ± 1.2 X10-6 A ch (B 0 a 1 - K + )= ± 0.12 ± 0.01 BF(B + a 1 + K 0 ) BF(a 1+ π + π + π - ) =17.4± 2.5 ± 2.2 X10-6 A ch (B + a 1 + K 0 ) =0.12± 0.11 ±

50 α B 0 π + π π 0 (ρπ) 0 : b u ud Can use Isospin as in π + π - pentagon relationship -> more terms to measure New method: use (known) resonance phase variation over Dalitz to analyze EW phase Eliminates some ambiguities Monte Carlo Interference Region. ρ + π - B 0 ρ + π - Monte Carlo B 0 ρ - π + B 0 ρ 0 π 0 ρ - π + ρ 0 π 0 50

51 α B 0 π + π π 0 (ρπ) 0 : b u ud N(B 0 π + π - π 0 ) = 2067 ± 86 Aρπ (ρ ± π ) = ± 0.05 ± 0.02 C (ρ ± π ) = 0.15 ± 0.09 ± 0.05 S (ρ ± π ) = ± 0.11 ± 0.04 ΔC (ρ ± π ) = 0.39 ± 0.09 ± 0.09 ΔS (ρ ± π ) = ± 0.14 ± 0.06 =! 0.45 ± 0.35( stat) ± 0.32( syst) = ± 0.57( stat) ± 0.43( syst) C00 (ρ 0 π 0 ) = ± 0.40 ± 0.53 PRL 98, (2007) S00 (ρ 0 π 0 ) = 0.02 ± 0.22 ± 0.09 hep-ex/ A S # # 0 0 " " 0 0 TDPA + isospin TDPA only 87 N B B = 383M N B B = 449M

52 γ GLW results A CP± #( B = #( B!! ± 2r( = " D " D (*) s) B R (*)0 CP± (*)0 CP± CP± K K (*) ( s) B (*)! (*)! sin% sin $ )! #( B ) + #( B + + " D " D (*)0 CP± (*)0 CP± 4 observables, 3 unknowns K K (*) + (*) + ) ) R CP± $ ( B [ $ ( B = 1+ r (*)2 ( s) B # D ± 2r (*) ( s) B ) + $ ( B % (*)0 (*)% + (*)0 (*) + CP± CP± = % (*)0 (*)% % (*)0 (*)% # D K K ) + $ ( B (*) cos" cos! ( s) B # D # D π π π ω φ K K ) )]/ 2 52

53 53 ADS results! " " # # # # )cos cos( 2 ) ] [ ( ) ] [ ( ) ] [ ( ) ] [ ( 2 2 D B D B D B ADS r r r r K D K B K D K B K D K B K D K B R = $ + % $ % $ + % $ % = + & + + & + & & + + & + & & + & ADS D B D B ADS R r r K D K B K D K B K D K B K D K B A / )sin sin( 2 ) ] [ ( ) ] [ ( ) ] [ ( ) ] [ (! " " # # # # + = $ + % $ % $ & % $ % = + + & + & & + & + + & + & & + & A ADS = 0.22 ± 0.61 ± observables, 5 unknowns γ

54 γ GGSZ Results Physical Variables r B, δ B,γ Gaussian Variables x + = r B cos( δ B +γ ), y + = r B sin( δ B +γ) x = r B cos( δ B γ ), y = r B sin( δ B γ) Modes in D KKπ( * ) K ( * ) Similar for Y +,Y - 54

55 CPV in ϒ(4S) Decay If large, would invalidate sin2β from TDCPA results Method: partial reconstruction ϒ(4S) B 0 B 0 Full reconstruction µ + J/ψ µ - π + - K S π + - K S J/ψ, η c Partial reconstruction N B B = 535M +3.6 N sig = events arxiv: (submitted to PRL) Br(ϒ(4S) B 0 B 0 J/ψK S +J/ψ(η c )K S ) < 4x10 7 (90%C.L.) SM expectation: ~1.4x

56 How this all started... In the early universe, for every billion ordinary particles annihilating with antimatter, one was left standing CKM CPV is too small to account for observed matter/anti-matter asymmetry by a factor of ~10-20 Due to Heavy Higgs, 12 factors of lambda for simplest process resulting in matter/anti-matter asymmetry 56

57 57