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Toru Iijima Nagoya University

New Physics Search in B Decays (Leptonic and Neutrino Modes) & Super B Factory. Toru Iijima Nagoya University. October 17, 2006 Heavy Quark and Leptons 2006 Munich. Talk Outline + Appology. Introduction B l n ( tn , mn , e n, l ng ) B ll (ee, mm , tt , ll g ) BK (*) nn, nn

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Toru Iijima Nagoya University

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

  2. Talk Outline + Appology • Introduction • Bln (tn, mn, en, lng) • Bll (ee, mm, tt, llg) • BK(*)nn, nn • Super KEKB • Summary Appology: Due to limited time, some of them cannot be mentioned or have to be put in backup .

  3. Higgs mediation 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). • B decay has many patterns to test the effects. Rare Decays !! Annihilation Box Penguin

  4. Hunting Rare Decays In 1993… CLEO First evidence of BK*g PRL 71, 674 (1993)

  5. 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 !

  6. Bln • Proceed via W annihilation in the SM. • SM Branching fraction Br(tn)=1.6x10-4 Br(mn)=7.1x10-7 Br(en)=1.7x10-11 Provide fB|Vub| • In two Higgs doublets model, charged Higgs exchange interferes with the helicity suppressed W-exchange. • If mn is also measured, lepton universality can be tested.  SUSY correction etc.

  7. Full Reconstruction Method • Fully reconstruct one of the B’s to tag • B production • B flavor/charge • B momentum Decays of interests BXu l n, BK n n BDtn, tn B e- (8GeV) e+(3.5GeV) Υ(4S) p full (0.1~0.3%) reconstruction BDp etc. B Single B meson beam in offline ! Powerful tools for B decays w/ neutrinos

  8. BtnAnalysis • Extra neutral energy in calorimeter EECL • 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 EECL arising only from beam background Higher EECL due to additional neutral clusters MC includes overlay of random trigger data to reproduce beam backgrounds.

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

  10. Results (Br & fB Extraction) • Measured branching fraction; • Product of B meson decay constant fB and CKM matrix element |Vub| • Using |Vub| = (4.39  0.33)×10-3 from HFAG 16% = 14%(exp.) + 8%(Vub) 15% fB = 216  22 MeV [HPQCD, Phys. Rev. Lett. 95, 212001 (2005) ]

  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, fB and the branching fraction must be changed. 0.46 New value 0.51 FPCP04 result The revised paper has been resubmitted, and posted as hep-ex/0604018v2.

  12. BtnSearch @ Babar • Babar searches for in a sample of 324x106 BB events • Reconstruct one B in a semileptonic final state BDlnX DK p, K ppp, K pp, Kspp (X=g, pfrom D*0 is not explicitly reconstructed) • Require lepton CM momentum > 0.8 GeV • Require that -2 < cosqB-D0l < 1 • Parent B energy and momentum are determined from the beam energy • Tagged B reconstruction efficiency ~0.7% • Discriminate signal from background using Eextra • tlepton is identified in the 4 decay modes

  13. BtnSearch @ Babar (cont.) • Observed excess is not significant yet (1.3s), and set a limit on the branching fraction and quote a central value. Deduced fB |Vub| Babar preliminary

  14. Constraints on Charged Higgs These regions are excluded. fB from HPQCD |Vub| from HFAG Much stronger constraint than those from energy frontier exp’s.

  15. If D|Vub| = 0 & DfB = 0 5ab-1 50ab-1 Br(Btn)/Dmd to cancel fB ? G.Isidori&P.Paradisi, hep-ph/0605012 Future Prospect: Btn • Br(Bt n) measurement: More luminosity help to reduce both stat. and syst. errors. • Some of the syst. errors limited by statistics of the control sample. • |Vub| measurement: < 5% in future is an realistic goal. • fB from theory: ~10% now  5% ? My assumption DfB(LQCD) = 5% Preliminary

  16. BaBar @ 208.7fb-1 w/ fully reconstructed tag; BD(*) X. Belle @ 140fb-1 w/ “inclusive ” reconstruction of the companion B. monoenergetic e or m recoiling against Btag Nobs = 0 in the signal box. Bmn, en @90%C.L. @90%C.L.

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

  18. l l l d l d • New Physics can enhance the branching fractions by orders of magnitude. ex.) loop-induced FCNC Higgs coupling Note: Present CDF limit;Br(Bsmm) < 1x10-7 (95%CL) is equivalent to Br(Bsmm) < 4x10-9. A0,H0, h0 Btt requires full-reco. tag. B0l+l- • Proceeds via box or penguin annihilation SM Branching fractions Flavor violating channel (B0e +m –, etc.) are forbidden in SM.

  19. B0l+l- (e+e-,m+m-,e+m-) Signal regions Events observed m+m– e+e– • B(B0e+e–) < 6.1 × 10-8 (90%CL) • B(B0m+m–) < 8.3 × 10-8 (90%CL) • B(B0e+ m–) < 18 × 10-8 (90%CL) 111 fb-1 Phys. Rev. Lett. 94, 221803 (2005) • B(B0e+e–) < 1.9 × 10-7 (90%CL) • B(B0m+m–) < 1.6 × 10-7 (90%CL) • B(B0e+ m–) < 1.7 × 10-7 (90%CL) e-m+ 78 fb-1 Phys. Rev. D 68, 111101 (2003) B(B0dm+m-) < 2.3×10-8 (90% CL) 780 pb-1 It would be interesting to see results with more data. What about U(5S) data at Super-B ?

  20. B0llg (BaBar@ 292fb-1) • 320 M BB events • 0.3 < mll < 4.9 (4.7) GeV for eeg (mmg) • Background from J/y, y (2S) decay (leptons) or p0 decay (g) • Reject qq background event shape in a Fisher discriminant • Observe 0 (3) events in the signal box in electron (muon) events e+ e-g m+ m-g B(B0 e+e-g) < 0.7 × 10-7 (90%CL) B(B0 m+m-g) < 3.4 × 10-7 (90%CL) Babar preliminary

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

  22. BK+nnextrapolated sensitivity (if SM) 3s @ 12ab-1, 5s @ 33ab-1 Need Super-B !! BK(*)nn • Babar @82fb-1 hadronic and semileptonic tagging • Belle @253fb-1 hadronic tagging • Belle @492fb-1 hadronic tagging +3.1 -2.6 Yield = 4.7 (1.7σ stat. significance)

  23. SuperKEKB  Asymmetric-energy e+e- collider to berealized by upgrading the existing KEKB collider.  Super-high luminosity  81035 cm-2s-1 1010 BB per yr.  8109t +t - per yr.  Letter of Intent is available at: http://belle.kek.jp/superb/loi Belle with improved rate immunity ECM=M((4s)) Higher beam current, smaller by* and crab crossing  L = 81035

  24. f b s B _ d _ s s Ks _ d DSfK0(July 2005) DSfK0(SuperKEKB) SM predictions Flavor Physics at SuperKEKB • Are there new CP-violating phases ? • Are there new right-handed currents ? • Are there new flavor-changing interactions with b, c or t ? SuperKEKB will answer these questions by scrutinizing loop diagrams.

  25. LFV Search at Super-B cf) Hayasaka at BNM2006 tlg PDG2006 Belle Babar Preliminary based on eff. and NBG of most sensitive analysis t3l, lh Estimated upper limit range of Br t3l tlg tlp/h(‘) tB g/p tl Ks Search region enters into O(10-810-9)

  26. Major Achievements Expected at SuperKEKB Case 1: All Consistent with Kobayashi-Maskawa Theory Search for New CP-Violating Phase in bgs with 1 degree precision CKM Angle Measurements with 1 degree precision Discovery of BgKnn Discovery of New Subatomic Particles sin2qW with O(10-4) precision Observations with U(5S), U(3S) etc. |Vub| with 5% Precision Discovery of BgDtn Discovery of Bgmn Discovery of CP Violation in Charged B Decays “Discovery” with significance > 5s Discovery of Direct CP Violation in B0gKp Decays (2005) Discovery of CP Violation in Neutral B Meson System (2001)

  27. 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 of CP Violation in Charged B Decays “Discovery” with significance > 5s Discovery of Direct CP Violation in B0gKp Decays (2005) # SUSY GUT with gluino mass = 600GeV, tanb = 30 Discovery of CP Violation in Neutral B Meson System (2001)

  28. Super-KEKB Status Crab crossing • Super-high luminosity  81035 cm-2s-1 • Natural extension of KEKB • With technology proven at KEKB • Many key components are tested at KEKB. Crab crossing will be tested in winter 2007. Ante-chamber Installed at KEKB Crab cavity Super-KEKB is a machine which can be build now.

  29. Super-KEKB Status • Letter of Intent (LoI) in 2004 • 276 authors from 61 institutions • available at http://belle.kek.jp/superb/loi • “Physics at Super B Factory” hep-ex/0406071 • Updates of physics reach and also new measurements (U(5S) run etc.) are extensively discussed. • BNM2006 workshop (Sep.13-14) http://www-conf.kek.jp/bnm/2006/ • 2nd meeting at Nara (Dec.18-19, after CKM2006@Nagoya) A lot of activities for physics and detector studies ! You are welcome to join !

  30. We need a Super B Factory ! • Super-KEKB aims at L=8x1035cm-2s-1, with tech. proven at KEKB. • A lot of activities for physics and detector studies. • HEP community in Japan is now discussing “Grand Lepton Collider” plan to accommodate both Super-KEKB and ILC. Stay tuned ! Summary • The first evidence of Btn has obtained by Belle @414fb-1.  Successful operation of B factories have finally brought the B leptonic decays on the stage. • O(ab-1) data will bring Bmn and Bdmm for serious examination. • These enable us to explore New Physics, esp. in large tanb region, together with other measurements; DmBS, Bsmm, BXsg and also t decays (tmh, tmg). • O(10ab-1) data will bring BKnn at horizon. (see talk by A.Weiler)

  31. References • Bln • Btn: Belle (hep-ex/0604018), BaBar (hep-ex/0608019) • Bmn, en: Belle (hep-ex/0408132), BaBar (hep-ex/0607110) • Blng: Belle (hep-ex/0408132) • Bll • Be+e-, m+m-, e+m- Belle (PRD68, 111101(R) (2003)) BaBar (PRL94, 221803(2005)), CDF • Be+e-g, m+m-g : BaBar(hep-ex/0607058) • Bt+t-: BaBar(PRL96, 241802 (2006)) • BKnn, nn • B+K+nn Belle(hep-ex/0507034), BaBar(PRL94, 101801 (2005)) • B0K*0nn Belle(hep-ex/0608047) • B0nn BaBar(PRL93, 091802(2004)) Due to limited time, some of them cannot be mentioned or have to be put in backup

  32. Backup

  33. H+ tanb t+ A0,H0, h0 MH(GeV) New Physics in large tanb • Leptonic decays (Bln, ll) are theoretically clean, free from hadronic uncertainty. • In particular, they are good probes in large tanb region, together with other measurements; DmBS, Bsmm, BXsg and also t decays (tmh, tmg). Ex.) G.Isidori & P.Paradisi, hep-ph/0605012 Charged Higgs Neutral Higgs See talk by A.Weiler

  34. Btn Candidate Event B+g D0 p+ K+p- p+p- B-gt - n e-nn

  35. Cont’d Charged Higgs Mass Reach (95.5%CL exclusion @ tanb=30) Only exp. error (DVub=0%, DfB=0%) Preliminary DVub=2.5%, DfB=2.5% Mass Reach (GeV) DVub=5%, DfB=5% Luminsoity(ab-1) Note) Ratio to cancel out fB may help (G.Isidori&P.Paradisi, hep-ph/0605012) from other measurements

  36. B0t+ t- (BaBar @ 210fb-1) • Experimentally very very challenging (2-4 neutrinos in the final state ! ) • High sensitive to NP Bsmm 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 t decays (tlnn, pn, rn) • Kinematics of charged partilce momenta and residual energy are fed into a neutral network to separate signal and BG Data Control sample Nexpect=281±48 Nobs=263±19 @90%C.L. Phys. Rev. Lett. 96, 241802 (2006)

  37. B0 n n (invisible) @Babar B pairs used: (88.5±1.0)×106 • Semileptonic tags : B0D(*)-l+n (D*-D0p-) • Require nothing in recoil: - no charged tracks, - limited # of neutral clusters. • ML fit to Eextra • Upper limit (frequentist) incl. systematics (additive;7.4events, multiplicative; 10.9%) nn – 8 nng Phys. Rev. Lett. 93, 091802 (2004) B(B0 invisible) < 22 × 10-5 (90%CL)

  38. Future Prospect: BKnn cf.) K.Ikado @ BNM2006 • Belle @ 250fb-1 (preliminary) Fully reconstructed tag (by modifying the PID criteria used in Btn analysis). Belle preliminary Consistent with BG expected Need Super-B !

  39. Advantages of SuperKEKB • Clean environment  measurements that no other experiment can perform. Examples: CPV in BgfK0, Bgh’K0 for new phases, BgKsp0gfor right-handed currents. • “B-meson beam” technique  access to new decay modes. Example: discover BgKnn. • Measure new types of asymmetries. Example: forward-backward asymmetry in bgsmm, see • Rich, broad physics program including B, t and charm physics. Examples: searches for tgmg and D-D mixing with unprecedented sensitivity. • No other experiment can compete for New Physics reach in the quark sector.

  40. Super B LHC ILC EDM LFV K physics Muon g-2 Neutrino 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) ? These grand questions can only be answered by experiments both at the luminosity and energy frontiers. SuperKEKB will play an essential role.

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