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Highlights of the Belle Experiment

Highlights of the Belle Experiment. A.Bożek NZ11. Selection of the most important Belle results since last SAB review (2005) : B 0 g h ' K 0 : first observation of time dependent CPV in rare B decays ; B -  t - n t : e vidence for purely leptonic decay

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Highlights of the Belle Experiment

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  1. Highlights of the Belle Experiment A.Bożek NZ11 Selection of the most important Belle results since last SAB review (2005): • B0 gh'K0:first observationof time dependent CPV in rare B decays; • B-  t-nt:evidence for purely leptonic decay (decay with missing energy); • New particles with charm; • First results from Bs ((5S) run). Precision tests of the Standard Model and New Physics searches at the B-Factory e+e-(4S)B0 B0 / B- B+ B0(db) B- (ub) Bs(sb) 0 Highlights of the Belle Experiment SAB Review 2007

  2. Physics analyses in Kraków Rare B decays: b  s: B- f0(980)K- , B0 f0(980)K*0 B decays with missing energy: b c -: B0 D*- +  New particle searches : -Dsj(2700) in B-D0D0K- analysis -Charmed baryons study • Krakow’s Belle group • 5 PhD physicists • 3 electronics eng. • 3 PhD students • 1 diploma student Highlights of the Belle Experiment SAB Review 2007

  3. qi W± Vij qj B Factory Physics Program • Studies of rare B, D and  decays with potential sensitivity to new physics; • Precise tests of the most stringent Standard Model (SM) predictions, • e.g. unitarity relations between elements of the quark mixing matrix. d s b u Cabibbo-Kobayashi- Maskawa(CKM) matrix c t f2() Unitarity Triangle being overconstrained at B factories f1(b) f3() Highlights of the Belle Experiment SAB Review 2007

  4. 13 countries, 57 institutes, ~400 collaborators Asymmetric e+e-collider 8GeV (e-)  3.5GeV (e+) More than milion BB pairs per day ~710x106 BB pairs Highlights of the Belle Experiment SAB Review 2007

  5. J/ b b b KS d d d c c s KS t B0 c c t J/ d d s Time-dependent CP violation (tCPV)“double-slit experiment” with particles and antiparticlesa flagship measurement at B-factories Quantum interference between two diagrams box diagram + tree diagram tree diagram + B0 B0 You need to “wait” (Dt0) to have the box diagram contribution. Highlights of the Belle Experiment SAB Review 2007

  6. _ 535 M BB pairs B0 tag _ B0 tag B0 J/y K0 tCPV Obtained precision is 1.3o +sin2f1 f1(b) sin2f1= 0.642 ±0.031 (stat) ±0.017 (syst) hep-ex/0608039 Highlights of the Belle Experiment SAB Review 2007

  7. _ _ _ _ b b b g c J/Y s f, h’... B0 s b c s B0 w _ d d d g _ s s K0 _ w K0 d d s f, h’... t g B0 s _ s K0 d B decays withb g stransitionone of the best new physics probes ? SM = SUSY as an example Extra CPV phase from New Physics Highlights of the Belle Experiment SAB Review 2007

  8. _ 535M BB tCPV in B0gh'K0 Dt distribution and asymmetry • First observation of tCPV • (5.6s) in a singlebgsmode sin2f1(b→s)= +0.64  0.10(stat)  0.04(syst) PRL 98, 031802 (2007) Highlights of the Belle Experiment SAB Review 2007

  9. f1frombgstransition Smaller than bgccs in all of 9 modes B0  J/y K0… Naïve average of allmodes sin2f1(b→s) = 0.52 ± 0.05 2.6 sdeviation Theory tends to predict positive shifts We need more statistics and more bs modes Highlights of the Belle Experiment SAB Review 2007

  10. B0 f0(980)K*0 Motivation: • Not observed yet,expected BF~10-6 • Expected to be dominated byb stransitions -mode with simple final state • In addition nature of f0(980) can be studied (candidate for four quark state or other exotic combinations). Started as adiploma work; can lead to an important physics output inhot field. Very Preliminary Results should be published this year Highlights of the Belle Experiment SAB Review 2007

  11. Decays of interests BXu l n, BK n n BDtn, tn B e- (8GeV) e+(3.5GeV) Υ(4S) p fully reconstructed second B i.e. BDp B B decays with missing energy • Fully reconstruct one of the B’s to : - tag BBevents • determine other B flavor/charge & momentum sensitive to new physics Method Powerful tools to study B decays with neutrinos Highlights of the Belle Experiment SAB Review 2007

  12. B+t+nt B+g D0 p+ K+p- p+p- B-gt -n e-nen Missing momentum Highlights of the Belle Experiment SAB Review 2007

  13. The First BtnEvidence Observation based on the residual energy in theelectromagnetic calorimeter not used in both B reconstruction. Signal + background +5.3 - 4.7 17.2 events in the signalregion. Measured branching fraction: Background Btn Signal PRL 97,251802 (2006) Another „multi-neutrino” mode:B0 D*- +  experimentally more difficult analysis is carried on in Kraków, results are expected this year. Highlights of the Belle Experiment SAB Review 2007

  14. New particles, charm spectroscopy e b e b q q q q c c e  e c c c c  s s • B factories are an abundant source of other particles: • charmed mesons and baryons:e+e- cc,B decays, … •  lepton „factory” : e+e- +-~700 M events New charmed mesons : new unresolved questions about charm spectroscopy Ds Y(3940) Z(3930) ,c , X X(3872) D Charmonium type K Belle 2003 2004 2005 BaBar at slac B-factory DsJ(2458) „cs” type Y(4260) DsJ(2317) Picture: R. Faccini, DOE review 2005 Highlights of the Belle Experiment SAB Review 2007

  15. sideband efficiency DsJ(2700) new state NewDsJin B+→D0D0K+ Dalitz plot M(D0D0) vs M(D0K) differs from 3-body phase space N=399 40 hep-ex/0608031 Interpretation still open Highlights of the Belle Experiment SAB Review 2007

  16. Conclusions and prospects We are in high statistics era at B factories( 1ab-1 ~109 BB) - many interesting & unexpected results 38 papers in Phys.Rev.Lett. (with discovery status) during 2005/2006 - powerful tool to study rare and experimentally difficult B decays that are not accessible in other environments Good prospects for next generation experiment at Super B-Factory SuperKEKB (50 ab-1 ~5*1010 BB) New physics searches in rare B &  decays, that are not accessible on hadron machines e.g: BK n n, BDtn,BD*tn, BXs/Xug t→m g, t→e g, … solve the b  s & other ~2.5 puzzles Highlights of the Belle Experiment SAB Review 2007

  17. Future plans Lpeak = 1.71034cm-2s-1 Ltot = 710 fb-1 (Dec. 2006) ~1010 BB/year !! & similar numberoft+t- world records ! Major upgrade of KEKB & Belle detector (>1yr shutdown) SuperKEKB We are here Lpeak (cm-2s-1) Lint 5x1034 ~1 ab-1 1.7x1034 700 fb-1 8x1035 ~10 ab-1 Highlights of the Belle Experiment SAB Review 2007

  18. (5S)test runs Bs -> Ds+p- BsBs , Bs*Bs, Bs*Bs* 9 events in Bs* Bs* 5.408< MBC<5.429 GeV/c2 Bs* Bs* Nev=20.0 ± 4.8 6.7 s CLEO PRL 54, 381 (1985) 1985: CESR (CLEO,CUSB) ~116 pb-1 at Y(5S) 2003: CESR (CLEO III) ~0.42 fb-1 at Y(5S) (5S) 2005: Belle, KEKB ~ 1.86 fb-1 at Y(5S) 2006, June 9-31: Belle, KEKB ~21.7 fb-1 at Y(5S) e+ e- -> Y(5S) -> BB,B*B, B*B*, BBp, BBpp, BsBs, Bs*Bs, Bs*Bs* sum of all Bs decay modes MC Highlights of the Belle Experiment SAB Review 2007

  19. Evidence of Btn Hunting Rare Decays • High luminosity • Good detector (PID, vertex…) • Analysis techniques • qq background suppression • Fully reconstructed tag Observation of bdg FB asymmetry in BK* l+l- Direct CPV in B0K+p- Beginning of B->fK0 saga Observation of BK l+ l- CPV in B decay Success of B factories brought rare B decays in leptonic and neutrino modes on the stage ! Highlights of the Belle Experiment SAB Review 2007

  20. Major Achievements Expected at SuperKEKB Case 2: New Physics with Extended Flavor Structure Search for New CP-Violating Phase in bgs with 1 degree precision Discovery of Lepton Flavor Violation intgmgDecays# CKM Angle Measurements with 1 degree precision Discovery of New Right-Handed Current in bgs Transitions # Discovery of BgKnn Discovery of New Subatomic Particles Discovery of New CP Violation inB0gfK0Decays# sin2qW with O(10-4) precision Observations with U(5S), U(3S) etc. |Vub| with 5% Precision Discovery of BgDtn Discovery of Bgmn “Discovery” with significance > 5s Discovery of CP Violation in Charged B Decays # SUSY GUT with gluino mass = 600GeV, tanb = 30 Discovery of Direct CP Violation in B0gKp Decays (2005) Discovery of CP Violation in Neutral B Meson System (2001) Highlights of the Belle Experiment SAB Review 2007

  21. _ B0 Principle of tCPV measurement CP-side m+ J/y m- (4S) resonance B1 electron KS/L B0 positron nm B2 p- bg = 0.425 (Belle) 0.56 (BaBar) K+ p- Flavor tag and vertex reconstruction Dz ~ 200mm (Belle) m+ • Fully reconstruct one B-meson which decays to CP eigenstate • Tag-side determines its flavor (effective efficiency = 30%) • Proper time (Dt) is measured from decay-vertex difference (Dz) Highlights of the Belle Experiment SAB Review 2007

  22. tCPV in B0 decays Vtd e.g. for J/ Ks S = -CPsin2f1 = +sin2f1 A = 0 to a good approximation (CP : CP eigenvalue) + Vtd Mixing-induced CPV Direct CPV Highlights of the Belle Experiment SAB Review 2007

  23. New ! Update after ICHEP2006 ! K.Ulmer Highlights of the Belle Experiment SAB Review 2007

  24. _ 535M BB Belle 2006: tCPV in B0gfK0 “sin2f1” = +0.50  0.21(stat)  0.06(syst) A = +0.07  0.15(stat)  0.05(syst) Dt distribution and asymmetry • Consistent with the SM (~1s lower) • The most precise measurement now • fKSandfKLcombined • background subtracted • good tags • Dt g –Dt forfKL unbinned fit SM hep-ex/0608039 Highlights of the Belle Experiment SAB Review 2007

  25. B0 D*- +  search Motivations: • BD(*)not observed yet • Decays with heavy fermions enhancement of effects beyond SM • Many avaiable observables fromdecays transverse or longitudinal polarisation • Semileptonic heavy quark decay – clear theoretical situation: good description of b quark in HQET • BG for BDdecay • Experimentally very difficult: • At least 2nin decay chain • Low effective Br:Effective Br for decay chain ~ 10-4 – 10-5 need for more effective reconstruction of Btag or/and higher statistics Results should be presented this year Highlights of the Belle Experiment SAB Review 2007

  26. JP = 1- sideband efficiency DsJ(2700) new state New DsJ in B+→D0D0K+ hep-ex/0608031 Dalitz plot M(D0D0) vs M(D0K) differs from 3-body phase space N=399 40 ψ(4160) reflection Highlights of the Belle Experiment SAB Review 2007

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