1 / 25

Highlights of the Belle Experiment

Highlights of the Belle Experiment. A.Bożek. 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

leone
Download Presentation

Highlights of the Belle Experiment

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Highlights of the Belle Experiment A.Bożek 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 Highlights of the Belle Experiment SAB Review 2007

  3. 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

  4. 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

  5. _ 535 M BB pairs B0 tag _ B0 tag B0 J/y K0 tCPV _ (r, h) Obtained precision is 1.3o f2(a) +sin2f1 f3(g) f1(b) (0,0) (0,1) sin2f1= 0.642 ±0.031 (stat) ±0.017 (syst) hep-ex/0608039 Highlights of the Belle Experiment SAB Review 2007

  6. _ _ _ _ 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

  7. _ 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

  8. 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

  9. 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

  10. 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 Method Powerful tools to study B decays with neutrinos Highlights of the Belle Experiment SAB Review 2007

  11. 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

  12. 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. Another „multi-neutrino” mode:B0 D*- +  experimentally more difficult Analysis is carried on in Kraków, results are expected this year. Measured branching fraction: Background Btn Signal PRL 97,251802 (2006) Highlights of the Belle Experiment SAB Review 2007

  13. New particles, charm spectroscopy e b e b q q q q e c c  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 K Belle 2003 2004 2005 BaBar at slac B-factory DsJ(2458) Y(4260) DsJ(2317) Picture: R. Faccini, DOE review 2005 Highlights of the Belle Experiment SAB Review 2007

  14. 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

  15. 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→m g, … solve the b  s & other ~2.5 puzzles Highlights of the Belle Experiment SAB Review 2007

  16. 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

  17. (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

  18. 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

  19. 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

  20. _ 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

  21. 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

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

  23. _ 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

  24. 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

  25. 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

More Related