New Physics Search in B Decays (Leptonic and Neutrino Modes) & Super B Factory

Transcription

1 New Physics Search in B Decays (Leptonic and Neutrino Modes) Missing & Super B Factory π K + π + Toru Iijima π π + e Nagoya University October 17, 2006 Heavy Quark and Leptons 2006 Munich

2 Talk Outline + Appology Introduction B lν (τν, μν, eν, lνγ) B ll (ee, μμ, ττ, llγ) B K (*) νν, νν Super KEKB Summary Appology: Due to limited time, some of them cannot be mentioned or have to be put in backup. 2

3 Introduction If New Physics found at LHC at TeV scale, they must appear in loops as well and change amplitudes. It is easier to see the effects when SM amplitudes are small (or zero). Rare Decays!! B decay has many patterns to test the effects. b Penguin Box Annihilation + + b γ, Z ν W t W s b W W + t s u ν Higgs mediation 3

4 Hunting Rare Decays In 1993 CLEO First evidence of B K*γ PRL 71, 674 (1993) 4

5 Hunting Rare Decays High luminosity Good detector (PID, vertex ) Evidence of B τν Analysis techniques qq background suppression Fully reconstructed tag Observation of b dγ FB asymmetry in B K* l + l - Direct CPV in B 0 K + π Beginning of B->φK 0 saga Observation of B K l + l - CPV in B decay Success of of B factories brought rare B decays in in leptonic and neutrino modes on on the stage!! 5

6 B lν Proceed via W annihilation in the SM. SM Branching fraction Provide f B V ub Br(τν)=1.6x10-4 Br(μν)=7.1x10-7 Br(eν)=1.7x10-11 In two Higgs doublets model, charged Higgs exchange interferes with the helicity suppressed W-exchange. Br =Br SM 2 m B 2 r, H r H = 1- tanβ 2 mh 2 If μν is also measured, lepton universality can be tested. SUSY correction etc. 6

7 Full Reconstruction Method Fully reconstruct one of the B s to tag B production B flavor/charge B momentum e (8GeV) Υ(4S) B B e+(3.5gev) π Decays of interests B Xu l ν, B K ν ν B Dτν, τν full (0.1~0.3%) reconstruction B Dπ etc. Single B meson beam in offline! Powerful tools for B decays w/ neutrinos 7

8 B τν Analysis Extra neutral energy in calorimeter E ECL Most powerful variable for separating signal and background Total calorimeter energy from the neutral clusters which are not associated with the tag B Minimum energy threshold Barrel : 50 MeV For(Back)ward endcap : 100(150) MeV Zero or small value of E ECL arising only from beam background Higher E ECL due to additional neutral clusters MC includes overlay of random trigger data to reproduce beam backgrounds. 8

9 The First B τν Evidence The final results are deduced by unbinned likelihood fit to the obtained E ECL distributions. Signal + background B τν Signal Background Signal shape : Gauss + exponential Background shape : second-order polynomial + Gauss (peaking component) Σ : Statistical Significance +5.3 Observe 17.2 events in the -4.7 signal region. Significance decreased to 3.5 σ after including systematics 9

10 Results (Br & f B Extraction) Measured branching fraction; Br B ( τν ) = ( ) Product of B meson decay constant f B and CKM matrix element V ub ( ) fv = GeV B ub Using V ub = (4.39 ± 0.33) 10-3 from HFAG f= GeV B % 16% = 14%(exp.) + 8%(V ub ) f B = 216 ± 22 MeV [HPQCD, Phys. Rev. Lett. 95, (2005) ] 10

11 Correction to the FPCP06 result Error in the efficiency calculation. Due to a coding error, the efficiency quoted in the 1st Belle preliminary result was incorrect. Treatment of the peaking background component. Peaking component is subtracted for the central value. Re-evaluate its systematic uncertainty. The data plots and event sample are unchanged. However, f B and the branching fraction must be changed. New value FPCP04 result BF( B + BF( B + τ τ ν ) = + ν ) = τ τ ( ) The revised paper has been resubmitted, and posted as hep-ex/ v2. 11

12 B τν Babar Babar searches for in a sample of 324x10 6 BB events Reconstruct one B in a semileptonic final state B DlνX D K π, K πππ, K ππ, K s ππ (X=γ, π from D*0 is not explicitly reconstructed) Require lepton CM momentum > 0.8 GeV Require that -2 < cosq B-D0l < 1 Parent B energy and momentum are determined from the beam energy Tagged B reconstruction efficiency ~0.7% Discriminate signal from background using E extra τ lepton is identified in the 4 decay modes 12

13 B τν Babar (cont.) Observed excess is not significant yet (1.3σ), and set a limit on the branching fraction and quote a central value. Babar preliminary Deduced f B V ub 13

14 Constraints on Charged Higgs Br = (1.79 ) exp Br = (1.59 ± 0.40) 10 SM -4 These regions are excluded. f B from HPQCD V ub from HFAG 2 m B 2 r H = 1- tan β 2 mh Brexp = =1.13±0.53 Br SM 2 Much stronger constraint than those from energy frontier exp s. 14

15 Future Prospect: B τν Br(B τν) measurement: More luminosity help to reduce both stat. and syst. errors. Some of the syst. errors limited by statistics of the control sample. V ub measurement: < 5% in future is an realistic goal. f B from theory: ~10% now 5%? If Δ V ub = 0 & Δf B = 0 My assumption Δf B (LQCD) = 5% 5ab -1 50ab -1 Lum. ΔB(B τν) exp Δ V ub 414 fb -1 36% 7.5% 5 ab -1 10% 5.8% 50 ab -1 3% 4.4% Br(B τν)/δm d to cancel f B? G.Isidori&P.Paradisi, hep-ph/

16 B μν, eν 208.7fb -1 Entries / / MeV/c w/ fully reconstructed tag; B D (*) X BABAR B μν BA BAR preliminary preliminary Monte Carlo 1200 B eν B B 1000 MC Background 0 0 B B cc qq,{q=u,d,s} Lepton Lepton momentum momentum (B (B frame) frame) (GeV/c) (GeV/c) signal signal Onpeak Data monoenergetic e or μ Nobs = 0 in the signal box. recoiling against Btag Br(B e ν ) < Br(B μν ) < fb -1 w/ inclusive reconstruction of the companion B Br(B e ν ) < (60fb ) -6-1 Br(B μν ) < (140fb 16

17 Future Prospect: B μν B μν is the next milestone decay mode. Measurements will offer a cross check to the results obtained by B τ ν. f B V ub determination. Test the lepton universality. Method? Inclusive-recon method has high efficiency but poor S/N. limit 1/ L Hadronic tag will provide very clean and ambiguous signals, but very low efficiency. Luminosity (ab -1 ) limit 1/L Standard Deviation K.Ikado at BNM2006 Extrapolation from the present Belle analysis (inclusive-recon.) 3σ at 1.3ab -1 5σ at 3.7ab -1 See also talk by Robertson at CERN flavour WS (May 2006) 17

18 B 0 l + l - Proceeds via box or penguin annihilation SM Branching fractions Br(B e e ) ~ d d 0 d νν ) = zero Br(B μμ) ~ 10 Br(B d d l l l l Flavor violating channel (B 0 e + μ, etc.) are forbidden in SM. New Physics can enhance the branching fractions by orders of magnitude. ex.) loop-induced FCNC Higgs coupling Note: Br(B s ) Vts = 25 Br(B d ) Vtd Br(B ττ ) m = τ 300 Br(B μμ) mμ 2 2 b d 6 tan β 4 ma A 0,H 0, h 0 Present CDF limit;br(bs μμ) < 1x10-7 (95%CL) is equivalent to Br(Bs μμ) < 4x10-9. B ττ requires full-reco. tag. + 18

19 B 0 l + l - (e + e -,μ + μ -,e + μ - ) Signal regions Events observed e + e μ + μ e - μ+ 111 fb fb pb -1 B(B 0 e + e ) < (90%CL) B(B 0 μ + μ ) < (90%CL) B(B 0 e + μ ) < (90%CL) Phys. Rev. Lett. 94, (2005) B(B 0 e + e ) < (90%CL) B(B 0 μ + μ ) < (90%CL) B(B 0 e + μ ) < (90%CL) Phys. Rev. D 68, (2003) B(B 0 d μ+ μ ) < (90% CL) It would be interesting to see results with more data. What about Υ(5S) data at Super-B? 19

20 B 0 llγ (BaBar@ 292fb -1 ) 320 M BB events 0.3 < m ll < 4.9 (4.7) GeV for eeγ (μμγ) Background from J/ψ, ψ (2S) decay (leptons) or π 0 decay (γ) Reject qq background event shape in a Fisher discriminant Observe 0 (3) events in the signal box in electron (muon) events Δ E (GeV) 0.2 e + e - γ 0.4 BABAR preliminary Δ E (GeV) 0.2 μ + μ - γ 0.4 BABAR preliminary (GeV/c ) m ES B(B 0 e + e - γ) < (90%CL) B(B 0 μ + μ - γ) < (90%CL) (GeV/c ) m ES Babar preliminary 20

21 B K (*) ν ν (b s w/ two ν s) B K (*) νν proceeds via one-loop radiative penguin and box diagrams. SM prediction Br ~ 4x10-6. It is highly sensitive to new physics, and theoretically very clean. But, experimentally very challenging. Signature: B K (*) + nothing. DAMA Nothing may be light dark matter NaI 3σ Region (see papers by Pespelov et al.). Direct dark matter search cannot see M<10GeV region. CDMS 04 CDMS 05 21

22 B K (*) νν -1 hadronic and semileptonic tagging Br(B hadronic tagging K νν) < (90%C.L.) 0 *0-5 Br(B K νν) < (90%C.L.) Br(B + -5 K νν)< (90%C.L.) -1 hadronic tagging *0-4 Br(B K νν) < (90%C.L.) Yield = (1.7σ stat. significance) B K + νν extrapolated sensitivity (if SM) 12ab -1, 33ab -1 Need Super-B!! 22

23 SuperKEKB Asymmetric-energy e + e collider to be realized by upgrading the existing KEKB collider. Super-high luminosity cm 2 s BB per yr τ + τ per yr. Letter of Intent is available at: E CM =M(ϒ(4s)) Belle with improved rate immunity Higher beam current, smaller β y * and crab crossing L =

24 Flavor Physics at SuperKEKB 1. Are there new CP-violating phases? 2. Are there new right-handed currents? 3. Are there new flavor-changing interactions with b, c or τ? SuperKEKB will answer these questions by scrutinizing loop diagrams. ΔS φk 0 (July 2005) B _ b d ΔS φk 0 (SuperKEKB) s_ s _ s d Ks φ SM predictions 24

25 LFV Search at Super-B τ lγ γ χ 0 τ τ μ ( e ) μ () e (m ) 2 l 23(13) PDG2006 Belle Babar cf) Hayasaka at BNM2006 based on eff. and N BG of most sensitive analysis τ 3l, lη τ h μ μ() s μ( s ) τ lγ τ lπ/η ( ) τ 3l τ l Ks τ B γ/π Search region enters into O( ) Estimated upper limit range of Br 25

26 Major Achievements Expected at SuperKEKB Case Case 1: 1: All All Consistent with with Kobayashi-Maskawa Theory Search for New CP-Violating Phase in b s with 1 degree precision CKM Angle Measurements with 1 degree precision Discovery of B Kνν Discovery of New Subatomic Particles sin 2 θ W with O(10-4 ) precision Vub with 5% Precision Discovery of B Dτν Observations with Υ(5S), Υ(3S) etc. Discovery of B μν Discovery with significance > 5σ Discovery of CP Violation in Charged B Decays Discovery of Direct CP Violation in B 0 Kπ Decays (2005) Discovery of CP Violation in Neutral B Meson System (2001) 26

27 Major Achievements Expected at SuperKEKB Case Case 2: 2: New New Physics with with Extended Flavor Flavor Structure Search for New CP-Violating Phase in b s with 1 degree precision Discovery of of Lepton Flavor Violation in inτ μγ μγdecays # # CKM Angle Measurements with 1 degree precision Discovery of of New New Right-Handed Current in in b s s Transitions # # Vub with 5% Precision Discovery of B Dτν Discovery of B Kνν Discovery of New Subatomic Particles Discovery sin of of 2 θnew W with CP CP O(10Violation -4 ) precision in inb 0 0 φk φk 0 0 Decays # # Observations with Υ(5S), Υ(3S) etc. Discovery of B μν Discovery with significance > 5σ # SUSY GUT with gluino mass = 600GeV, tanβ = 30 Discovery of CP Violation in Charged B Decays Discovery of Direct CP Violation in B 0 Kπ Decays (2005) Discovery of CP Violation in Neutral B Meson System (2001) 27

28 Super-KEKB Status Super-high luminosity cm -2 s -1 Natural extension of KEKB With technology proven at KEKB Crab crossing Many key components are tested at KEKB. Crab crossing will be tested in winter Ante-chamber Installed at KEKB Crab cavity Super-KEKB is a machine which can be build now. 28

29 Super-KEKB Status Letter of Intent (LoI) in authors from 61 institutions available at Physics at Super B Factory hep-ex/ Updates of physics reach and also new measurements (Υ(5S) run etc.) are extensively discussed. BNM2006 workshop (Sep.13-14) 2 nd meeting at Nara (Dec.18-19, after CKM2006@Nagoya) A lot of activities for physics and detector studies! You are welcome to join! 29

30 Summary The The first evidence of of B τν has has obtained by by Successful operation of of B factories have finally brought the the B leptonic decays on on the the stage. O(ab -1-1 )) data data will will bring B μν and and B d μμ d for for serious examination. These enable us us to to explore New New Physics, esp. esp. in in large tanβ tanβregion, together with with other measurements; ΔmBS, B s μμ, s B X s γ s γand also also τ decays (τ μη, τ μγ). (see talk by A.Weiler) O(10ab -1-1 )) data data will will bring B Kνν at at horizon. We need a Super B Factory!! Super-KEKB aims aims at at L=8x cm cm -2-2 s -1-1,, with with tech. proven at at KEKB. A lot lot of of activities for for physics and and detector studies. HEP HEP community in in Japan is is now now discussing Grand Lepton Collider plan to accommodate both Super-KEKB and ILC. plan to accommodate both Super-KEKB and ILC. Stay tuned! 30

31 References B lν B τν: Belle (hep-ex/ ), BaBar (hep-ex/ ) B μν, eν: Belle (hep-ex/ ), BaBar (hep-ex/ ) B lνγ: Belle (hep-ex/ ) B ll B e+e-, μ+μ-, e+μ- Belle (PRD68, (R) (2003)) BaBar (PRL94, (2005)), CDF B e+e-γ, μ+μ-γ : BaBar(hep-ex/ ) B τ+τ-: BaBar(PRL96, (2006)) B Kνν, νν B + K + νν Belle(hep-ex/ ), BaBar(PRL94, (2005)) B 0 K *0 νν Belle(hep-ex/ ) B 0 νν BaBar(PRL93, (2004)) Due to limited time, some of them cannot be mentioned or have to be put in backup 31

32 Backup 32

33 New Physics in large tanβ Leptonic decays (B lν, ll) are theoretically clean, free from hadronic uncertainty. In particular, they are good probes in large tanβ region, together with other measurements; Δm BS, B s μμ, B X s γ and also τ decays (τ μη, τ μγ). Ex.) G.Isidori & P.Paradisi, hep-ph/ Charged Higgs b ν u Neutral Higgs b H + τ + tanβ d A 0,H 0, h 0 + See talk by A.Weiler MH(GeV) 33

34 B τν Candidate Event BELLE B + D 0 π + B - τ - ν K + π - π + π - e - νν Missing K + π + π e π π + 20 cm 34

35 Cont d Charged Higgs Mass Reach (95.5%CL tanβ=30) Mass Reach (GeV) Only exp. error (ΔV ub =0%, Δf B =0%) ΔV ub =2.5%, Δf B =2.5% ΔV ub =5%, Δf B =5% Luminsoity(ab -1 ) Note) Ratio to cancel out f B may help (G.Isidori&P.Paradisi, hep-ph/ ) Br(B τν ) V ub m V d td V V ub td from other measurements 35

36 B 0 τ + τ - 210fb -1 ) Experimentally very very challenging (2-4 neutrinos in the final state! ) High sensitive to NP Bs μμ at hadron machines Analysis Reconstruct one B in a fully hadronic final state B D (*) X =>280k events In the event remainder, look for two τ decays (τ lνν, πν, ρν) Kinematics of charged partilce momenta and residual energy are fed into a neutral network to separate signal and BG Data Nobs=263±19 Phys. Rev. Lett. 96, (2006) Control sample Nexpect=281±48-3 Br(B ττ ) <

37 B 0 ν ν B pairs used: (88.5±1.0) 10 6 Semileptonic tags : B 0 D ( * )- l + ν (D* - D 0 π - ) Require nothing in recoil: - no charged tracks, - limited # of neutral clusters. ML fit to E extra Ns =17 ± 9 Nb = Upper limit (frequentist) incl. systematics (additive;7.4events, multiplicative; 10.9%) B(B 0 invisible) < (90%CL) νν ννγ Phys. Rev. Lett. 93, (2004) 37

38 Future Prospect: B Kνν 250fb -1 (preliminary) Fully reconstructed tag (by modifying the PID criteria used in B τν analysis). Belle preliminary cf.) BNM2006 Consistent with BG expected Signif. 3σ 5σ Lum (ab -1 ) Need Super-B! 38

39 Advantages of SuperKEKB Clean environment measurements that no other experiment can perform. Examples: CPV in B φk 0, B η K 0 for new phases, B Ksπ 0 γ for righthanded currents. B-meson beam technique access to new decay modes. Example: discover B Kνν. LHCb (0.002 ab -1 ) Measure new types of asymmetries. Example: forward-backward asymmetry in b sμμ, see Rich, broad physics program including B, τ and charm physics. Examples: searches for τ μγ and D-D mixing with unprecedented sensitivity. No other experiment can compete for New Physics reach in the quark sector. ΔS(φKs) ΔS(K + K - Ks) ΔS(η Ks) ΔS(KsKsKs) ΔS(π 0 Ks) sin2χ(bs J/ψφ) S(K *0 γ) Br(B Xsγ) A CP (B Xsγ) C 9 w/ A FB (K * l + l - ) C 10 w/ A FB (K * l + l - ) Br(Bs μ + μ - ) Br(B + K + νν) Br(B + Dτν) Br(B 0 Dτν) sin2φ 1 φ 2 (ππ isospin) φ 2 (ρπ) φ 3 (DK (*) ) φ 3 (Bs KK) φ 3 (Bs DsK) V ub SuperKEKB at 50 ab -1 ΔS(φKs) ΔS(K + K - Ks) ΔS(η Ks) ΔS(KsKsKs) ΔS(π 0 Ks) sin2χ(bs J/ψφ) S(K *0 γ) Br(B Xsγ) A CP (B Xsγ) C 9 w/ A FB (K * l + l - ) C 10 w/ A FB (K * l + l - ) Br(Bs μ + μ - ) Br(B + K + νν) Br(B + Dτν) Br(B 0 Dτν) sin2φ 1 φ 2 (ππ isospin) φ 2 (ρπ) φ 3 (DK (*) ) φ 3 (Bs KK) φ 3 (Bs DsK) V ub no info no info no info

40 Role of SuperKEKB What is the origin of CP violation? What is the origin of the matter-dominated Universe? What is the flavor structure of new physics (e.g. SUSY breaking)? EDM K physics LHC Super B Neutrino ILC LFV Muon g-2 These grand questions can only be answered by experiments both at the luminosity and energy frontiers. SuperKEKB will play an essential role. 40

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