1. CP Asymmetries: New Results from Belle Kay Kinoshita University of Cincinnati Belle Collaboration KEK, August 13, 2003 Weak interaction: CP, CKM matrixWeak interaction: CP, CKM matrix B(eauty) mesons & CP asymmetry B production: e + e – ->  (4S) at KEKBB production: e + e – ->  (4S) at KEKB Belle experiment Highlights for 2003 Highlights for 2003 Selected CP & other results (preliminary) Selected CP & other results (preliminary)Plans

2. KEK, August 13, 2003 2 CP Violation Why is it of interest? matter-antimatter asymmetry in universe requires CP-violating interactions (Sakharov 1967) Weak interaction - the only known force that violates CP symmetry (a little).. but to 1998, only in K L (1963) violates P symmetry (maximally) … but preserves CP symmetry (mostly) right-handed particles, left-handed antiparticles. no coupling to LH particles, RH antiparticles. allows particle to change identity (flavor) is source of CP asymmetry in K L ? in universe? What is source of CP asymmetry in K L ? in universe? … step back, look at weak coupling strengths …

3. KEK, August 13, 2003 3 Weak coupling strengths Inelegant !! Couplings: no generation x-ing, except no generation x-ing, except charged-current quark charged-current quark leptons: ~same leptons: ~same quarks: all different, approx quarks: all different, approx generation-conserving generation-conserving W ± "charged current" Z 0 "neutral current" (+antifermion) Standard Model = 12 fermion flavors (+antifermion) + strong, EM, weak forces, unification of EM+weak 3* generationsx2 typesx2 ea, stable, but for weak interaction *generations distinguished only by mass

4. KEK, August 13, 2003 4 Elegance restored: GIM mechanism Picture strong doublets, generations “ degenerate, ” perturbed by weak force: new doublets no generation x-ing, universal W-coupling (=g F, seen in leptons) d', s', b' are linear combinations of d, s, b: Cabibbo-Kobayashi-Maskawa (CKM) matrix complex preserves metric “ orthogonality = unitary } Explains (Glashow-Iliopoulos-Maiani) suppression of flavor-changing neutral currents multiplicity of charged current couplings AND ……. uct d's'b'

5. KEK, August 13, 2003 5 RI … for >2 generations, e.g. 3, {9 R +9 I } dof constrained by unitarity: 4 free parameters, incl. 1 irreducible imaginary part >>>> CP Violation >>>> (Kobayashi-Maskawa 1973) Makoto Kobayashi Toshihide Maskawa First 3rd- generation particle (  ) seen 1975

6. KEK, August 13, 2003 6 3-generation Matrix (  "unitarity triangle" Self-consistent if CKM is correct d s b u V ud V us V ub c V cd V cs V cb t V td V ts V tb {1/g F x couplings} = from decay rates,  0.220 ± 0.002 A  0.81 ± 0.08 |  i  |  0.36 ± 0.09 |  i  |  0.79 ± 0.19 V ub *V ud V cb *V cd V tb *V td V cb *V cd + 1 += 0 =>  {i=1,k=3}: V ub *V ud +V cb *V cd +V tb *V td =0

7. KEK, August 13, 2003 7 CKM CP phenomenology B 0 ->ππ B 0 ->  π B 0 ->J/  K s B 0 ->  K s B 0 ->D ( * ) D ( * ) B 0 -> D*π B 0 ->D*  B->D CP K first result CP asymmetry - due to ≥3 generations -> need process w. all 3 (occurs with many B decays), interference in  2 processes (but not too many) -> probe different angles w different decays Program: are all asymmetries consistent w single KM phase? KM phase?

8. KEK, August 13, 2003 8 e.g. B -> J/  K s for sin 2  1 (Sanda/Bigi/Carter) CP asymmetry from x-term(s) - no theoretical uncertainty:  arg(V td 2 ) = 2  1 (no cc of hadronic phase under CP) tree (real V ij ) + mixing+tree (  V td *2 ) This is only the cleanest, simplest - "golden mode"

9. KEK, August 13, 2003 9 CP phenomenology: variations  V tb *2 V td 2 V cb V cd * mixing+ " 2 paths, different phases, + mixing e.g. B -> J/  π 0 2 paths, different phases, + mixing  V tb *2 V td 2 V tb V td * (relative amplitudes, strong phase not known)  V cb * V cd TreePenguin  V tb * V td mixing+ " Bottom line: "direct" CP asymmetry possible "direct" asym

10. KEK, August 13, 2003 10 B production: } B BB threshold e-e-e-e- e+e+e+e+   CP=–1,conserved   + e - ->  (4S) flavor tag @t=  : e, µ, K ±,... effective eff ~30% CP mode @ t=  t BR < 10 –3 t=0 first B decay (t=0), break CP B2B2B2B2 B1B1B1B1  z≈  t  c ~200 µm 2nd decay at t=  t What else is needed? >10 7 B's just to get started - KEKB >10 7 B's just to get started - KEKB hadron (K/π) ID - hadron (K/π) ID - dE/dx, Aerogel, TOF dE/dx, Aerogel, TOF lepton ID - CsI, multilayer µ lepton ID - CsI, multilayer µ <<200µm vertexing – <<200µm vertexing – double-sided silicon strip double-sided silicon strip

11. KEK, August 13, 2003 11 KEKB e – 8.0 GeV e + 3.5 GeV 22 mr  = 0.425 L max = 1.06 X 10 34 cm –2 s –1 (world record) Data (6/1999–6/2003)  L dt = 158 fb –1 @{  (4S)+off(~10%)} (1.52x10 8 B events)  E* beam ) = 2.6 MeV IP size = 77µm(x) x 2.0µm(y) x 4.0mm(z)

12. KEK, August 13, 2003 12 Belle detector Charged tracking/vertexing - SVD: 3-layer DSSD Si µstrip – CDC: 50 layers (He-ethane) Hadron identification – CDC: dE/dx – TOF: time-of-flight – ACC: Threshold Cerenkov (aerogel) Electron/photon – ECL: CsI calorimeter Muon/KL – KLM: Resistive plate counter/iron

13. KEK, August 13, 2003 13 …the people …the people 274 authors, 45 institutions many nations many nations

14. KEK, August 13, 2003 14 Belle physics results 58 papers published or in press (1st in 3/2001) 54 abstracts submitted to XXI Lepton-Photon (Fermilab) 18 - CP asymmetry in B decay 25 - B decay non-CP 8 - charm hadrons 1 - QCD 2 - tau Physics topics overlap in many analyses, e.g., discovery of new charmonium states in B decays.

15. KEK, August 13, 2003 15 Recent highlights CP and related time-dependent CP measurements time-dependent CP measurements update of J/  K s (  1 ) with J/  π 0 (~  1 ), D *+ π – (2  1 +  3 ),  K s (  1 ) evidence/observation evidence/observation B-> K*l + l -, π 0 π 0, D + D -, π 0  0 new method for  3 : Dalitz plot analysis new method for  3 : Dalitz plot analysis D 0 K + {D 0 ->K s π + π – } Charm new processes/ particles new processes/ particles new excited D s states new charmonium first radiative: D 0 ->  difference of CP lifetimes in D (y CP ) difference of CP lifetimes in D (y CP )

16. KEK, August 13, 2003 16 B decay reconstruction at  ~3MeV/c 2  ~10MeV Kinematics for final selection:exploit exclusive pair production of B exclusive pair production of B narrow resolution of collision energy narrow resolution of collision energy  E  E* cand –E* beam  0 (E* beam  s 1/2 /2)  ~10-50 MeV, depending on mode M bc (Beam-constrained mass) M bc  (E* beam 2 -p* cand 2 ) 1/2 Signal region ~3% background EE M bc

17. KEK, August 13, 2003 17 Time dependent measurements: Fully reconstructed 2911 used in fit BELLE-CONF-0353 sin2  1 : {charmonium}+K s tag (CP=–1)

18. KEK, August 13, 2003 18 sin2  1 : {charmonium}+K L tag (CP=+1) p B * (cms) [2332 events, purity ~0.60] 1399±67 signal J/  K L

19. KEK, August 13, 2003 19 Flavor tagging: all remaining particles bcs l-l-l-l- l+l+l+l+ K–K–K–K– D0D0 π+π+ D *+ high-p lepton (p*>1.1 GeV): b-> l - net K charge b->K – medium-p lepton, b->c-> l + soft π b->c{D *+ ->D 0 π + } hard π b->{c}π – X * multidimensional likelihood,  >99% or π – Flavor-specific B 0 (B->D *+ l ) mixing amplitude w wrong-tag fraction w classify events based on expected w (MC) - 6 bins. (actual w -B 0 mixing amplitude in data)> effective efficiency =  (1-2w): net (28.7±0.5)%

20. KEK, August 13, 2003 20  z: vertex reconstruction  K-K- K-K-  Constrained to measured IP in r-    t ~1.43 ps (rms) Overall eff. = 87% zz Validate resolution via lifetime  B0 = 1.551±0.018 ps (PDG02: 1.542±0.016) z

21. KEK, August 13, 2003 21 Fitting  t distribution use data wherever possible to validate unbinned maximum likelihood fit, includes - signal root distribution (analytic) - wrong tag fraction (const) flavor-specific tags -> w, mixing oscillation (  m d ) - background: right & wrong tag (MC, parametrized) - detector & tagging  z resolution parametrized,evt-by-evt - params from lifetime fits, validate by measuring  B,  D,  m d accounts for detector resolution, poorly measured tracks, physics (e.g. charm), approximation of  t=  z/  c Checks- separate opp CP tags, verify null signal for flavor-specific tags

22. KEK, August 13, 2003 22 Measurement of sin2  1 with 142 fb – 1 Raw asymmetry BELLE-CONF-0353 sin2  1 = 0.733±0.057±0.028 consistent with no direct CPV. 5417 evts Poor tags Good tags raw

23. KEK, August 13, 2003 23 Separate CP odd/even Raw asymmetry (all r-bins) BELLE-CONF-0353 CP = +1 sample (B 0 ->J/  K L ) sin2  1 = 0.80±0.13 CP = -1 sample sin2  1 = 0.73±0.06

24. KEK, August 13, 2003 24 Latest average from {cc}K sin2  1 (Belle 2003, 140 fb - 1 ) =0.733±0.057±0.028 sin2  1 (BaBar 2002, 81 fb - 1 ) =0.741±0.067±0.033 sin2  1 (NEW World Av.) =0.736±0.049

25. KEK, August 13, 2003 25 b->{c c d} decays: B->J/  π 0 (CP=+1) 88.6±10.0 _ BELLE-CONF-0342 B->J/  π 0 S=–0.72±0.42 (stat. only) (expect -sin2  1 if penguin is small) tree + penguin (relative amplitudes, strong phase not known)

26. KEK, August 13, 2003 26 b->{c c d}: observation of D + D - Yield : 24.3 ± 6.0 Significance : 5.0 Efficiency : 7.95 % B= (2.46 ± 0.61 ± 0.42) x 10 – 4 May be used in the future for time-dependent CP asymmetry measurements _

27. KEK, August 13, 2003 27 More time-dependent sin2  1 – or new physics modes dominated by b->sqq penguins In the absence of New Physics, S = sin2  1

28. KEK, August 13, 2003 28 Time-dependence in b->s penguins: S = 0.51 ± 0.26 ± 0.05 +0.18 -0.00 3rd error: due to uncertainty in CP content. (A=-0.01±0.16±0.04) S = 0.43±0.27±0.05 BELLE-CONF-0344 [sin2  1 (world average) = 0.736±0.049 ] (  K s excluded) poor tags good tags

29. KEK, August 13, 2003 29 b->s penguins: search for new physics 68±11 In the absence of New Physics, S=sin2  1eff = sin2  1 Theoretically cleanest example: Belle (78 fb –1 ): S=-0.73±0.64±0.22

30. KEK, August 13, 2003 30 CP Asymmetry in B->  K S sin2  1eff = –0.96 ±0.50 +0.09 –0.11 [Current sin2  1 (world average) = 0.736±0.049 ] (A=-0.15±0.29±0.07) Control Sample S=–0.09±0.26 BELLE-CONF-0344 differs by 3.5 

31. KEK, August 13, 2003 31 Probability & statistics SM sin2  1eff Feldman-Cousins treatment including systematic from CP in the background finds this value ruled out at 99.95% CL or 3.5 

32. KEK, August 13, 2003 32 Systematic uncertainties Correlation between A and S ? A=-0.15 ±0.29±0.07 If A is fixed to zero, S=-0.99±0.50 SA Fitting near |S|=1 +0.06 –0.00 – backgnd K + K – K s, f 0 (980)K s +0.00 –0.08 ±0.04 background fraction-other  0.05±0.04 Vertex algorithm  0.02  0.05 Total +0.09 –0.11 ±0.07

33. KEK, August 13, 2003 33 BaBar result  K S BaBar 2003: 110 fb -1 sin2  1eff = +0.45±0.43±0.07 (A=0.38±0.37±0.12)

34. KEK, August 13, 2003 34 BaBar B->  K S Systematics sin2  1eff = -0.18±0.51±0.09 sin2  1eff = +0.45±0.43±0.07 81 fb -1 : 110 fb -1 : Data size increased and was reprocessed. Extensive checks with data and Toy MC. The large change is attributed to a 1σ statistical fluctuation.

35. KEK, August 13, 2003 35 BaBar B->  K S Systematics

36. KEK, August 13, 2003 36 Observation of B 0 ->π 0 π 0 Gronau, London PRL 65, 3381 (1990): isospin analysis of B->ππ to obtain  2 without time-dependence π 0 π 0 is most difficult step. B=[1.7±0.6±0.2]x10 –6

37. KEK, August 13, 2003 37 Charm: observation of new charmonium state in B ± ->K ± π + π – J/  bins of π + π – J/  mass M=3871.8±0.7±0.4 MeV/c 2 BELLE-CONF-0352

38. KEK, August 13, 2003 38 Observation of first radiative D decay D 0 ->  (  ->K + K – ) large bg from D 0 ->  π 0 large bg from D 0 ->  π 0 (also first observation) (also first observation) distinguish by  ->KK distinguish by  ->KK helicity angle helicity angle distribution distribution B=[2.60 ]x10 –5 +0.70–0.61+0.15–0.17 BELLE-CONF-0346

39. KEK, August 13, 2003 39 Summary Belle in August 2003: KEKB L= 1.06x10 34 cm –2 s –1 <- @design! (1x10 34 cm –2 s –1 ) KEKB L= 1.06x10 34 cm –2 s –1 <- @design! (1x10 34 cm –2 s –1 ) 152M B pairs: sin2  1 has become a "precision" measurement 152M B pairs: sin2  1 has become a "precision" measurement first results on alternative probes of sin2  1 (or new physics!) first results on alternative probes of sin2  1 (or new physics!) B->J/  π 0 - penguin may be small (need more data) B->J/  π 0 - penguin may be small (need more data) surprise deviation in B->  K s - 3.5  - hints of new physics? consistency with SM in other b->sss developing sensitivity to  2,  3 developing sensitivity to  2,  3 observations/hints in many modes, possibly CP in future observations/hints in many modes, possibly CP in future large charm sample - new states, modes, searches for NP large charm sample - new states, modes, searches for NPNext 500 fb –1 by 2005 500 fb –1 by 2005 Luminosity >@ design Luminosity >@ design the CP challenge: just getting started - stay tuned! the CP challenge: just getting started - stay tuned!