Charmless B Decays. Wolfgang Gradl For thebabar and BELLE collaborations. Heavy Quark and Leptons The University of Edinburgh I V E R S I T Y

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1 Charmless B Decays Wolfgang Gradl For thebabar and BELLE collaborations The University of Edinburgh T H E U N I V E R S I T Y O H F E D I N B U R G Heavy Quark and Leptons 26 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 1/ 36

2 Outline Introduction CharmlessBdecays TheBfactories Constraining S f =S f sin2β sin2β inb qqs penguins Constraining SM pollution BF,CPAnd A ch Measurements related to α/φ 2 B η ( ) K ( ) B VV decays Other charmlessbdecays All results preliminary unless journal reference given W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 2/ 36

3 Charmless hadronic B decays b V ub ū Contributing amplitudes: CKM suppressed trees, penguins,... Can be used to study Interfering SM amplitudes CP violation Effects of new particles in loops (New Physics?) Perturbative calculations possible (QCD factorisation, pqcd, SCET) Constrain models B b B b B W + W + W + ū, c, t g ū, c, t s, d η s, d W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 3/ 36

4 The B factories: BELLE and BABAR BELLE 1.5 T solenoid (superconducting) Calorimeter 658 CsI(Tl) cyrstals Cherenkov Detector 144 quartz bars 11, PMTs e + (3.1 GeV) e (9 GeV) Silicon Vertex Tracker 5 double sided layers Drift Chamber 4 layers Instrumented Flux Return layers e + e Υ(4S) BB Asymmetric beam energies KEK-B:8GeVe 3.5GeVe + L int 64 fb 1 so far PEP-II:9GeVe 3.1GeVe + L int 46 fb 1 so far W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 4/ 36

5 Measuring time-dependent CP asymmetries Unitarity triangle α/φ 2 V ud V ub V cd V cb V td V tb V cd V cb Unitarity of the CKM matrix: V td V tb +V cdv cb +V udv ub = γ/φ 3(,) β/φ 1 (1,) Time-dependent CP asymmetry inb -B mixing A cp ( t) = Γ(B f) Γ(B f) Γ(B f) + Γ(B f) = S f sin m d t C f cos m d t For exampleb J/ψK S (b c cs):s J/ψK S =sin2β,c J/ψK S = W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 5/ 36

6 Constraining S f =S f sin2β W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 6/ 36

7 sin2βfromb qqspenguins Measure CPV inb spenguin dominated decays:s f,c f Standard model & penguin only: S f =sin2β New Physics can show up in loops and modifys f Sub-dominant standard model amplitudes introduce additional weak and strong phases S f sin2β even without NP So, what is SM expectation for S f S f sin2β? Measuring related modes helps pin down expected deviations b ccs φ K η K f K S π K S sin(2β eff ) = sin(2φ e 1 ff ) π π K S Average -.84 ±.71 ω K S ρ K S H F A G Moriond 26 PRELIMINARY World Average.69 ±.3 Average.47 ±.19 Average.5 ±.9 Average.75 ±.24 Average.31 ±.26 Average.63 ±.3 Average.17 ±.58 K + K - K Average.51 ± K S K S K S Average.61 ± sin2β fromb c cs W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 7/ 36

8 ConstrainingSMpollutioninB φk Constrain sub-dominant (V ub ) contributions tob φk S via SU(3) flavour relations Grossmanetal., Phys. Rev. D 68:154 (23) S φk 1 S 4 B(ρ π ) 1 4 B(ωπ ) + 1 r 3 ˆcB(φη) sb(φη ) h i + ˆcB(ωη) sb(ωη ) cb(ρ η) sb(ρ η ) h i B(K K ) B(K K ) B(φπ ) Search forb K K S BABAR, hep-ex/665,28 fb 1 Upper limit at 9% C.L.: B(K K ) + B(K K ) < SU(3) upper bound S φk <.43 Improved B(φπ ) BABAR, Phys. Rev. D 74:1112,211 fb 1 Upper limits at 9% C.L.: B(B φπ ) < B(B + φπ + ) < W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 8/ 36

9 ConstrainingSMpollutioninB η K Constrain S η K S using flavour SU(3) andb η ( ) π, η η. Gronauetal., Phys. Lett. B 596, 17 Expected B in the ranges (η ( ) π ) and (η η). Upper limits at9% CL: F B(B ηπ ) < B(B η η) < B(B η π ) < B(η π ) = ( ) 1 6 BABAR, 211 fb 1 Phys. Rev. D 73:7112 BELLE, Phys. Rev. Lett. 97:6182 (next slide) With new upper limits, expect.46 <S η K S <.94 Gronauetal., hep-ex/6885 Also improvement forsin2α measured inb π + π W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 9/ 36

10 B η π BELLE BB, Phys. Rev. Lett. 97:6182 B + η π + B = ( ) 1 6 A ch = ±.4 PreviousBABAR: B = (4. ±.8 ±.4) 1 6 Phys. Rev. Lett. 95, B η π B = ( ) 1 6 Significance 3.1 σ BABAR: < Phys. Rev. D 73, 7112 η π + clearly seen η π not clear W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 1/ 36

11 SearchforB K SK SK L Pure b s ss penguin, analoguous tob K SK SK S Avoids SM pollution CP eigenstate Resonant φk S contribution small, but non-resonant component may be large: B = ( ) 1 6 Chengetal., Phys. Rev. D 72, 943, using factorisation Experimentally difficult: ǫ B i small Assuming uniform 3-body phase space, and excluding φ: UL at9% CL: B(B K SK SK L) < BABAR, 211 fb 1, Phys. Rev. D 74:325 Limited use for understanding CPV inb qqs W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 11/ 36

12 CPasymmetriesinB ω π/k Events / 2 MeV Events / 2 MeV Events / 2 MeV Events / ps Asymmetry 5 (a) (c) (e) m ES (GeV) ES m BABAR (a) B (b) B (c) Events / 2 MeV Events / 2 MeV Events / 2 MeV (b) (d) (f) E E (GeV) ωπ + ωk + ωk S t, t - t (ps) CP tag b qqs, dominated by single penguin Expect S ωk.1 and A ch [Phys. Lett. B 62,143; Phys. Rev. D 72, 146] BABAR: B(1 6 ) A ch B + ωπ ±.7 ±.4.1 ±.1 ±.1 B + ωk ±.6 ±.4.5 ±.9 ±.1 B ωk S 6.2 ±1. ±.4 ωk S, fixc =: S = , S =.12 ± fb 1, Phys. Rev. D 74:116 BELLE: B(1 6 ) A ch B + ωπ ±.6 ±.5.2 ±.9 ±.1 B + ωk ±.6 ± ±.1 B ωk S ±.4 B ωπ < BB, hep-ex/6922 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 12/ 36

13 Measurementsrelatedto α/φ 2 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 13/ 36

14 UpdatesonB ρρ Set ofb ρ ρ, ρ + ρ andb + ρ + ρ to extract angle α/φ 2 Updates for all Branching Fractions, CP asymmetries from both BABAR and BELLE See talk by Christos Touramanis on Wednesday morning W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 14/ 36

15 B a ± 1 (126) π Can be used to extract α/φ 2 up to 4-fold ambiguity [Aleksanetal., Nucl. Phys. B 361, 141] Sub-leading penguin amplitude with different weak phase dilutes α Can be overcome by exploiting symmetries: Isospin [Gronau & London (199)] Approximate SU(3) flavour [Dighe, Gronau & Rosner (1998); Gronau & Zupan (25)] Events / 1 MeV Events / 24 MeV First step: measure branching fraction E (GeV) (a) (c) m a (GeV / c ) 1 Events / 1 MeV Events / m ES (GeV / c ) 1 5 (b) (d) Fisher Nice signal seen (N sig =421 ±48) AssumeBR(a + 1 (3π)+ ) =1% B(B a ± 1 π ) = (33.2 ±3.8 ±3.) 1 6 BABAR Phys. Rev. Lett. 97:5182 Next step: time dependent analysis W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 15/ 36

16 SearchforB a + 1 ρ b uūd transition: with sufficient statistics, could be used to measure α/φ 2 B 5π important background contribution for B ρρ analyses Little known about this decay: Theory: B(B a ± 1 ρ )B(a + 1 (3π)+ ) = Experiment: B(B a ± 1 ρ ) < [Baueretal., Z. Phys. C 34, 13 (1987)] using V ub /V cb =.8 [ARGUS, Phys. Lett. B 241, 278 (199), 214 pb 1 ] -ln( L / L max ) stat. only with systematics Assumef L =1to get most conservative upper limit (9% C.L.): Signal Yield B(B a ± 1 ρ )B(a + 1 (3π)+ ) < BABAR, 1 fb 1, Phys. Rev. D 74:3114 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 16/ 36

17 B η ( ) K ( ) W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 17/ 36

18 B η ( ) K ( ) B(B η K) found unexpectedly large (CLEO, 1997) Understood? Interference between two dominant penguin amplitudes [Lipkin 1991] plus enhancements fromm s, form factors, higher-order in α s [Beneke & Neubert 23] Predicts ηk large, η K small unless flavour singlet diagram important Important in light of measuringsin2β inb η K [ G. Dubois-Felsmann] W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 18/ 36

19 B η K BELLE B + η K + B = (69.2 ±2.2 ±3.7) 1 6 A ch =.28 ±.28 ±.21 B η K B = ( ±4.3) 1 6 BELLE, BB, Phys. Rev. Lett. 97, 6182 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 19/ 36

20 B ηk /ρ BELLE B ηk (892),ηρ BELLE hep-ex/6834 B(1 6 ) BABAR hep-ex/685 B ηk 15.9 ±1.2 ± ±1.1 ±.8 B + ηk ± ±1.8 ±1.3 B + ηρ ±.34 B ηρ <1.9 Confirm earliear measurements of ηk Agree with predictions Direct CP asymmetries consistent with New: ηk 2 and η(kπ) (no predictions so far) B η(kπ) K2 (143) andkπ S-wave B(1 6 ) B η(kπ) 11. ±1.6 ±1.5 B + η(kπ) ±2.6 ±2.6 B ηk2 9.6 ±1.8 ±1.1 B + ηk ±2.7 ±1.4 Events / 4 MeV η(kπ) Events / m Kπ (GeV) cos(θ H ) (S wave) K + 2 (143) Signal-enhanced projection plots W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 2/ 36

21 B η K /ρ Branching Fraction (1 6 ) Decay mode Theoretical predictions BABAR 211 fb 1 SU(3) flavour QCD fact. hep-ex/6719 B η K ± 1.1 ±.5 (4.3 σ) B + η K ±.8 (3.6 σ) <7.9 B η ρ (.3 σ) <3.7 B + η ρ (3.2 σ) <14 B η f (98) B(f π + π ) (.2 σ) <1.5 Phys. Rev. Nucl. Phys. D 68,7412 B 675, 333 Predictions have large error, both compatible with measurements η ( ) ρ likely to be very small Predicted pattern in η ( ) K ( ) seen Events / 4 MeV/c Events / (.13) m (GeV/c 2 K ) + π cos θ * H K W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 21/ 36

22 B(B (η, η ) (K ( ), π, ρ)) CLEO Belle BABAR PDG26 New Avg. HFAG August 26 ηπ ηπ + ηk ηk + ηρ ηρ + ηk ηk + η π η π + η ρ η ρ + η K η K + η K η K BranchingRatio 1 6 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 22/ 36

23 B VVdecays W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 23/ 36

24 PolarisationinB VVdecays Longitudinal polarisation fraction f L invv decays: θ * K π - + K * K φ ρ /f θ ρ π - d 2 Γ π + dcos θ 1 dcos θ (1 f L)sin 2 θ 1 sin 2 θ 2 +f L cos 2 θ 1 cos 2 θ 2 Helicity conservation arguments f L 1 m2 v m 2 B Valid for tree-dominated decays. Penguins? (factorisation?) Experiment: ok for ρρ:fl.95 ρρ, ωρ, ωω tree-dominated φk, ρk, ωk penguin-dominated Surprise:fL.5 for φk What about ρk, ωk? W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 24/ 36

25 SearchforB ωvdecays f L σ σ.4.3 5σ Branching Fraction(B ω ρ )( 1 ) B(B + ωρ + ) = (1.6 ± ) 1 6 f L (ωρ + ) =.82 ±.11 ±.2 A ch (ωρ + ) =.4 ±.18 ±.2 B(B ωk ) < B(B + ωk + ) < B(B ωρ ) < B(B ωω) < B(B ωφ) < B(B ωf ) < Polarisation large, as expected for tree-dominated decay BABAR 211 fb 1, Phys. Rev. D 74:5112 Reasonable agreement with predictions [e.g. Alietal., Phys. Rev. D 6,145; Cheng & Yang, Phys. Lett. B 511, 4] W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 25/ 36

26 B ρk ) Events / 35.5 MeV + ρ * K (B f L B + ρ + K m K + π (GeV) BR(B K * ρ + ) (1 ) B(ρ + K ) = (9.6 ±1.7 ±1.5) 1 6 f L (ρ + K ) =.52 ±.1 ±.4 A ch (ρ + K ) =.1 ±.16 ±.2 B(ρ K ) = (5.6 ±.9 ±1.3) 1 6 f L (ρ K ) =.57 ±.9 ±.8 A ch (ρ K ) =.9 ±.19 ±.2 BABAR, hep-ex/6757 SignificantKπ S-wave component Better agreement with previous BELLE results (Phys. Rev. Lett. 95:14181) Polarisation.5 as expected for penguin-dominated W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 26/ 36

27 B VV Polarisation penguin CLEO Belle BABAR Polarizations of Charmless Decays CDF PDG24 New Avg. HFAG July 26 φk + φk K ρ + ωρ + K + ρ K ρ? ρ ρ ρ + ρ ρ + ρ tree Longitudinal Polarization Fraction (fl) W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 27/ 36

28 Other charmless B decays W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 28/ 36

29 NewresultsonB ππ,kπ,kk Updated branching fractions Improved statistics asks for radiative corrections BABAR extracts non-radiative BF B : Γ incl P 1 P (E max ) = Γ(B P 2 1 P 2 +nγ) P E γ<e max = Γ P 1 P 2 + Γ P1 P 2 nγ(e max ) Γ incl P 1 P (E max ) = Γ 2 P 1 PG P1 2 P 2 (E max ) Baracchini, Isidori, Phys. Lett. B 633, 39 Mode BELLE BABAR B(1 6 ) B(1 6 ) B (1 6 ) hep-ex/6915 hep-ex/683 π + π 5.1 ±.2 ± ±.4 ± ±.4 ±.3 K + π 2. ± ±.6 ± ±.6 ±.6 K + K <.4 <.4 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 29/ 36

30 NewresultsonB ππ,kπ,kk Updated results for all BF K K andk K + have statistical significance >5σ b dhadronic penguins finally observed! Mode BABAR BELLE B(1 6 ) B(1 6 ) B π π 1.48 ±.26 ± B + π + π 5.12 ±.47 ± ± B ± K ± π 13.3 ±.56 ± ± B + K π ±1.1 ± ±1.3 B + K K ±.44 ± B K K 1.8 ±.28 ± ±.9 B K Sπ 1.5 ±.7 ± hep-ex/6716 Phys. Rev. Lett. 94, 1883 hep-ex/6836 hep-ex/6796 hep-ex/6849 hep-ex/6915 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 29/ 36

31 Time-dependentCPviolationinB K K Pure b ds s penguin New window for CPV in penguin decays Allows estimate of penguin contribution inb ππ via flavour SU(3) Direct CP asymmetry expected to be zero Measured asb K SK S S = C =.4 ±.41 ±.6 / 2 ps Events Asymmetry B tags T [ps] B tags T [ps] t (ps) S σ 2σ 3σ C BABAR, hep-ex/6836 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 3/ 36

32 DalitzplotanalysisofB + K + K + K Full Dalitz plot analysis, measure amplitudes and relative phases FitB + andb separately for A ch 45 13(K K ) (GeV 2 /c 4 ) + s s 13 >s 23 Events/(.9MeV/c 2 ) χ 2 /bins=14/1 E <4MeV 2394 ± 63 events (GeV 2 + s (K K ) /c ) me S(GeV/c 2 ) B(B + K + K + K ) = (35.2 ±.9 ±1.6) 1 6 Non-resonant component not flat across DP W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 31/ 36

33 c c c DalitzplotanalysisofB + K + K + K BABAR m (X ) =1.539 ±.2GeV/c 2 Γ (X ) =.257 ±.33GeV/c 2 Phys. Rev. D BELLE: doublet of solutions m (X ) =1.524 ±.14/1.491 ±.1GeV/c 2 Γ (X ) =.136 ±.23/.145 ±.29GeV/c 2 Phys. Rev. D 71,923 (25) 2 (a) 1 Mass projection plots 14 (b) ) MeV/ Events/(5 2c ) MeV/ Events/( χ 2 /bins=56/56 ) MeV/ Events/(5 2c χ 2 /bins=66/ m2 3(K K )(GeV/ 2 ) m1 3(K K )(GeV/ 2 ) B(B ± K ± φ) = (8.4 ±.7 ±.7 ±.1) 1 6 B(B ± K ± χ c ) = (1.84 ±.32 ±.14 ±.24) 1 6 BB bkg qq bkg B(B + K + K + K ) = (35.2 ±.9 ±1.6) 1 6 BABAR, 25 fb 1 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 31/ 36

34 SearchforB η η K Motivation: Large B(B η K) CP violation inb P P Q [Gershon & Hazumi, 24], e.g. observation ofb K SK SK S [BELLE, Phys. Rev. D 69, 121,BABAR, Phys. Rev. Lett. 95, 1181 ] Results (@9% CL): 2 Events / 2 MeV/c (a) (c) B(B + η η K + ) < B(B η η K ) < BABAR, 211 fb 1, Phys. Rev. D 74:3115 Events / 2 MeV (GeV/c ) E (GeV) m ES W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 32/ 36 (b) (d) η η K + η η K

35 B φφk b s ss with additional s s pair Direct CPV could be enhanced in interference between non-sm decays and decays via η c BELLE, hep-ex/6916 Search for charmless decays by reqiringm φφ below charm threshold BELLE Events / 2 MeV/c 2 Events / 2 MeV/c 2 (a) φφk ± m φφ <2.85GeV/c 2 Events / 2 MeV 6 (c) φφk M bc (GeV/c 2 ) Events / 2 MeV 25 (b) φφk ± (d) φφk E (GeV) Charmless: A ch = ±.2 η ck + : A ch = ±.2 W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 33/ 36

36 Summary Many new and updated results from bothb factories Impressive agreement between BELLE andbabar Rare charmlessbdecays help to improve understanding of Standard Model amplitudes More and more precise results to come with more data φk + φk K ρ + K π K + π a K + 1 π ± K + K K(143) π K(143) + π K(143) π + K + π π Charmless B Branching Fractions K π + π K + π + π CLEO Belle BABAR CDF PDG26 New Avg. K + KSKS ωρ + K + π π + π π + K + π K π + ρ + ρ ρ + ρ ρ π ± K + K K K + K K + ηk ηk + ηk + π K f(98) K + f(98) HFAG August 26 ηπ + π K π + η K + K + π + π Branching Ratio x 1 6 K ρ K + ρ K + ρ K K K + K ηk + ηπ + π π π + π ρ π π + π φφk + φφk η π + ηk + (143) η K KSKSKS ωk + ωk ωπ + K + f(98) ηk (143) ηk2 (143) ηρ + φk φk ρ π + ρ + π η K W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 34/ 36

37 Backup Slides W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 35/ 36

38 Detecting a signal Largest backgrounds frome + e qq Kinematic variables: E =E B E beam m ES = E beam p B E (GeV) (GeV) m ES 5 1 Event shape for background suppression: qq b b W. Gradl (U. Edinburgh) Charmless B Decays HQL 26 36/ 36