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Search for BNV, LNV, LFV at (Super-) Belle/KEKB

Search for BNV, LNV, LFV at (Super-) Belle/KEKB. Toru Iijima / Nagoya University. September 22, 2007 Search for Baryon and Lepton Number Violation Int’l Workshop @ LBL. The KEKB Collider. Belle detector. Ares RF cavity. e + source. e - (8.0GeV) × e + (3.5GeV) ⇒ U (4S) →BB

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Search for BNV, LNV, LFV at (Super-) Belle/KEKB

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  1. Search for BNV, LNV, LFV at (Super-) Belle/KEKB Toru Iijima / Nagoya University September 22, 2007 Search for Baryon and Lepton Number Violation Int’l Workshop @ LBL

  2. The KEKB Collider Belle detector Ares RF cavity e+ source • e- (8.0GeV) × e+ (3.5GeV) • ⇒U(4S) →BB • ⇒Lorentz boost: bg = 0.425 • Finite crossing angle • - 11mrad ×2 • Operation since 1999. SCC RF(HER) ARES(LER) Peak luminosity 1.71 x 1034 cm-2s-1 ! The World Highest Luminosity

  3. Belle Detector Toru ijima, B-L workshop

  4. KEKB Integrated Luminosity world records ! ~1010 BB & tt /year !! Lpeak = 1.71034cm-2s-1 Ltot = 710 fb-1 (Jun.30, 2007) NBB/tt=O(1011) s(BB) ~ 1.1nb, s(tt) ~ 0.9nb 8.0x108 BB + 6.3x108tt SuperKEKB NBB/tt=O(109) NBB/tt=O(107) KEKB / Belle Major Upgrade Crab cavities @ CESR Unique opportunity to study BNV, LNV, LFV in higher generation ! Toru ijima, B-L workshop

  5. BNV in Higher Generation Hou, Nagashima, Soddu, PRD72,095001 (2005) • B,L violating t, D, B decays with right-handed four-fermion couplings. proton decay limits; BNV t/D/B decays are strongly suppressed by the proton stability, But Experimental redundancy is still important ! t D B Toru ijima, B-L workshop

  6. NP search in t decays t lepton is the charged lepton, which is … • In the 3rd generation • Probe for the NP flavor mixing between 3⇔1/3⇔2 gen. • Heavy • Rate enhancement • Q>0 for decays to baryonic final states. t lepton is an unique laboratory to study… B-L conserving. B-L violating. • BNV • LNV • LFV t-pg, pp0, pK0, Lp-, Lp- BAU Leptogenesis t-e+/m+ + h-h- (h=p,K) t-e-/m- + g, l+l-, h+h-, h0, V0 Toru ijima, B-L workshop

  7. General Analysis Procedure p p- • Signal side: t decay of interest • Tag side: t  1 trk w/ n g + missing • 1-prong decays occupy >80% of the t decay. • Loose constraint on n based on Pmiss, M2miss. • Background • tt, continuum (qq), mm, ee, … • Particle ID • Signal evaluation based on Minv ~ Mt & DE ~ 0 • Signal region is open after analysis cuts are finalized. L Signal side p+ t- t+ p+ Tag side n DE=ERec – ECM Toru ijima, B-L workshop

  8. Kinematical Constraint • Use correlation between m2miss and pmiss. • Signal decays distribute around m2miss ~ zero (no. n on the signal side). p p- L Signal side p+ t- t+ p+ Tag side n Signal MC Data Y.Miyazaki et al., PLB632(2006)51-57 This cut removes 81% of tt and 77% of qq backgrounds, while keeping 89% of the signal. tt MC qq MC (uds) Toru ijima, B-L workshop

  9. Hadron-ID @ Belle • Hadron-ID @ Belle is based on the response of sub-detectors; • Threshold-type Aerogel Cherenkov Counter (ACC) n = 1.011.03 depending on q • Time-Of-Flight (TOF) • Ionization loss in CDC (dE/dx) Pth(p) = 0.99  0.57 GeV/c Pth(p) = 6.6  3.8 GeV/c Proton-ID performance w/ a nominal cut Eff(p) = 70% Fake(pp) = 4% Fake(Kp) = 11% • Combined to form a likelihood; • Use a cut on the likelihood ratio; •  pg, pp0 analyses use a • different cut At Super-Belle, large improvement is expected by using Ring imaging type Cherenkov detectors Toru ijima, B-L workshop

  10. L Reconstruction • The L candidates are reconstructed via pp- decay channel. • Selection parameters; • Angle difference between PL and IP –VTX. • Flight distance of L • Closest approach of the L daughter tracks to IP. • Particle ID cut for daughter tracks. Data Histo: tt +qq MC L selection efficiency ~ 80% Purity ~ 90% Signal MC Y.Miyazaki et al., PLB632(2006)51-57 Toru ijima, B-L workshop

  11. tpg, pp0 BELLE-CONF-0433 hep-ex/ 0408117 • tpg (86.7fb-1) • tpp0 (153.8fb-1) 5s signal box D=17.8±11.1 • Nobs = 16 • Nbkg = 9.1±1.7 (expected) • Br (t-pg) < 3.0×10-7 • Nobs = 70 • Nbkg = 52.2±7.3 (expected) • Br (t-pp0) < 6.5×10-7 D=6.9±4.3 (UL determined by an unbinned ML fit) Toru ijima, B-L workshop

  12. tLp @154fb-1 Y.Miyazaki et al., PLB632(2006)51-57 We evaluate UL using 5s ellipse. BKG are extrapolated from 15s box assuming flat dist. B-L conserving (t-Lp-) B-L violating (t-Lp-) 5s ellipse tt MC qq MC (uds) S90: Feldman-Cousins UL of #signals @ 90% CL. including systematic errors (POLE) Only a few background  Will be improved by 1/Lint BKG: tt (~1/2) + qq (~1/2) Toru ijima, B-L workshop

  13. Slepton mass matrix LFV in t Decays • Probe for 3⇔1/3 ⇔2 gen. mixing in the charged lepton sector. t3l, lh tlg • Br(t) = O(103-5) x Br(m). Enough chance to see tmg or tlll. • The two decays have different sensitivity for different NP models.

  14. signal data tlg, lh,lh’,lp0 t→mg t→mg,eg @535fb-1 (hep-ex/0705.0650 submittedd to PLB) Br(t→mg)<4.5x10-8(90%C.L.) Br(t→eg)<1.2x10-7 (90%C.L.) t→e/m + h,h’,p0@ 401fb-1 (PLB648, 341 (2007)) Br(t→lh,lh’,lp0) <(6.5-16)x10-890%C.L. signal region Bkg. from tt/mm+ initial state g t→mh(→gg) ⇒Upper limits for LFV t decays are approaching O(10-8) t→e/m + h,h’,p0 Only a few background  Will be improved by 1/Lint Toru ijima, B-L workshop

  15. t→lll: Background suppression BG events Signal topology eemm(eeee) Bhabha(mm) electron-vetoon the tag-side (e-e+e- and e-m+m-) g-conversion veto (e-e+e- and m-e+e-) m2miss and pmiss (e-e+e-, m-m+m-, e-m+m-, m-e+e-) Toru ijima, B-L workshop

  16. tlll @535fb-1 New ! signal data • Efficiency: 6.0%－12.5% • Nbkg (expected) = 0 – 0.4 events • No event found in the signal region • Obtained upper limit (90%CL) Br<(2.0-4.1)×10-8 Improved by 4.9-7.0 from Belle previous results @ 90fb-1 teee tmmm preliminary The most stringent upper limits among LFV t decays Still a few background  Will be improved by 1/Lint Toru ijima, B-L workshop

  17. tlV0@543fb-1 New ! t→mf t-m-K*0 Still a few background  Will be improved by 1/Lint Toru ijima, B-L workshop

  18. tlhh @158fb-1 Y.Yusa et al., PLB640(2006)138-144 tsignal m/e + 2 chg. tracks ttag  m/e + ng Background: tt, qq Continuum bkg. suppression by t flight length & R2 2D PDF  Likelihood ratio qq MC (uds) Signal MC UL (x10-7, 90%CL) * * * * * <7.3 <2.0 <3.0 <3.1 <7.2 <1.6 <1.9 <2.7 <7.3 <2.9 <4.8 <3.4 <8.0 <4.4 * LNV *Still a few background  Will be improved by 1/Lint Toru ijima, B-L workshop

  19. Summary for non-SM t Decay Search Upper limits of LFV t decay BNV ▼ ▼ ▼ ▼ ▼ ▼ ▼ ▼ t→ef,ew t→lh,lh’,lp0 t→mf,mw t→lhh’ t→lg t→3leptons New results this summer ULs for all LFV t decays are approaching the 10-8 level Toru ijima, B-L workshop

  20. Future prospect • Extrapolated sensitivity at 5ab-1 PDG2006 Belle Babar based on eff. and NBG of most sensitive analysis Estimated upper limit range of Br Ambiguity due to the stat. error of the bkg. estimation in the preset data.

  21. Super-KEKB Interaction Region Crab crossing q=30mrad. by*=3mm New QCS New Beam pipe 8GeV (e+, 4.1A) 3.5GeV (e-, 9.6A) More RF power Damping ring • Increase beam currents • 1.6 A (LER) / 1.2 A (HER) • → 9.4 A (LER) / 4.1 A (HER) • Smaller by* • 6 mm→3 mm • Increase xy • 0.059→>0.24(W-S) Linac upgrade L=8x1035cm-2s-1

  22. Crab Cavity • Superconducting crab cavities (1LER and 1HER) have been installed, and being tested at KEKB. Toru ijima, B-L workshop

  23. Crab Status • Crab cavity installed in Jan. 2007. • Beam-beam tune shift (0.088) achieved at low currents. • Beam current gradually increased  L=1034cm-2s-1 with crab crossing by June 2007. • Still need R&D/tuning to see L improvement (simulation predicts x2). y (beam-beam simulation) crab crossing HER LER Crab OFF 22mrad crossing Crab ON Toru ijima, B-L workshop

  24. Belle Upgrade Aerogel Cherenkov counter + TOF counter g “TOP” + RICH CsI(Tl) 16X0 g pure CsI (endcap) Si vtx. det. 4 lyr. DSSD SC solenoid 1.5T g 2 pixel/striplet lyrs. + 4 lyr. DSSD Tracking + dE/dx small cell + He/C2H5 • remove inner lyrs. Use fast gas m / KL detection 14/15 lyr. RPC+Fe g tile scintillator New readout and computing systems Toru ijima, B-L workshop

  25. Summary • B-factories provide an unique opportunity to study BNV, LNV, LFV in higher generation. • The present KEKB provides 6x108tt pairs  New results for LFV search using the full data sets are approaching to O(10-8). • Super-KEKB will provide x ~50-100 statistics.  The search region will enter into O(10-9) for many decays.  Good chance to see LFV t decays.  BNV can be tested too.

  26. Backup Slides

  27. 13 countries, 55 institutes, ~400 collaborators International Collaboration: Belle Seoul National U. Shinshu U. Sungkyunkwan U. U. of Sydney Tata Institute Toho U. Tohoku U. Tohuku Gakuin U. U. of Tokyo Tokyo Inst. of Tech. Tokyo Metropolitan U. Tokyo U. of Agri. and Tech. Toyama Nat’l College U. of Tsukuba VPI Yonsei U. Nagoya U. Nara Women’s U. National Central U. National Taiwan U. National United U. Nihon Dental College Niigata U. Osaka U. Osaka City U. Panjab U. Peking U. U. of Pittsburgh Princeton U. Riken Saga U. USTC IHEP, Vienna ITEP Kanagawa U. KEK Korea U. Krakow Inst. of Nucl. Phys. Kyoto U. Kyungpook Nat’l U. EPF Lausanne Jozef Stefan Inst. / U. of Ljubljana / U. of Maribor U. of Melbourne Aomori U. BINP Chiba U. Chonnam Nat’l U. U. of Cincinnati Ewha Womans U. Frankfurt U. Gyeongsang Nat’l U. U. of Hawaii Hiroshima Tech. IHEP, Beijing IHEP, Moscow

  28. Physics Targets at Super-B • CP violation • Precise CKM • Rare decays • FCNC decays • Tauonic decays • t decays • Lepton flavor violation • CPV in lepton sector Search for new origin of flavor mixing and CPV. Using O(1010) B and t (~100 x now)

  29. T LFV Prospect • Br~O(10-89) at Super B factory ! tmg tmh tmmm tmgsuffers from background due to ISR.

  30. Ante-chamber with solenoid field New crab cavity Ante-chamber Circular-chamber Build-up of electron clouds Super-KEKB (cont’d) • Head-on collision w/ Crab cavity Will be tested in 2006. • Ante-chamber /solenoid for reduction of electron clouds

  31. 4 Vertexing 4 Tracking 4 Particle ID 4 EM Cal 4 KL & m Pixel det. Issues • Higher background • Higher event rate • Require special features Small cell Fast gas Si-tracker • radiation damage and occupancy • fake hits and pile-up noise in the EM - higher rate trigger, DAQ and computing F-DIRC+TOP Aerogel RICH • low p m identification • full recon. eff. • hermeticity ; n “reconstruction” Pure CsI Liquid-Xe etc. 4 Fully pipelined readout 4 Large scale computing LST Scintillator New Challenge! Intensive R&Ds! Detector Upgrade

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