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

e + source Ares RF cavity Belle detector SCC RF(HER) ARES(LER) The KEKB Collider e - (8.0GeV) × e + (3.5GeV) ⇒  (4S) → BB ⇒ Lorentz boost:  = Finite crossing angle - 11mrad ×2 Operation since Peak luminosity 1.71 x cm -2 s -1 !

3 Belle Detector 2007/9/22Toru ijima, B-L workshop

~10 10 BB &  /year !! Crab cavities KEKB / Belle Major Upgrade 4 KEKB Integrated Luminosity L peak = 1.7  cm -2 s -1 L tot = 710 fb -1 (Jun.30, 2007) world records !  (BB) ~ 1.1nb,  (  ) ~ 0.9nb 8.0x10 8 BB + 6.3x10 8  N BB/  =O(10 9 ) N BB/   O(10 11 ) N BB/  =O(10 7 CESR 2007/9/22Toru ijima, B-L workshop

Hou, Nagashima, Soddu, PRD72, (2005) B,L violating , D, B decays with right-handed four-fermion couplings. BNV in Higher Generation 2007/9/22Toru ijima, B-L workshop 5 proton decay limits;  D B BNV  /D/B decays are strongly suppressed by the proton stability, But Experimental redundancy is still important !

NP search in  decays In the 3 rd generation –Probe for the NP flavor mixing between 3 ⇔ 1/3 ⇔ 2 gen. Heavy –Rate enhancement –Q>0 for decays to baryonic final states. 2007/9/22Toru ijima, B-L workshop 6 BNV LNV LFV  lepton is the charged lepton, which is …    p , p  0, pK 0,     B-L conserving. B-L violating.    e + /  + + h - h - (h= ,K)    e - /  - + g, l + l -, h + h -, h 0, V 0 BAU Leptogenesis

General Analysis Procedure Signal side:   decay of interest Tag side:   1 trk w/ n  + missing –1-prong decays occupy >80% of the  decay. –Loose constraint on based on P miss, M 2 miss. Background – , continuum (qq), , ee, … Particle ID Signal evaluation based on M inv ~ M  &  E ~ 0 Signal region is open after analysis cuts are finalized. 2007/9/22Toru ijima, B-L workshop 7 ++  ++   p  Signal side Tag side  E=E Rec – E CM

Kinematical Constraint Use correlation between m 2 miss and p miss. Signal decays distribute around m 2 miss ~ zero (no. on the signal side). 2007/9/22 Toru ijima, B-L workshop 8 ++  ++   p  Signal side Tag side Signal MC Data qq MC (uds)  MC Y.Miyazaki et al., PLB632(2006)51-57 This cut removes 81% of  and 77% of qq backgrounds, while keeping 89% of the signal.

Belle Belle is based on the response of sub-detectors; –Threshold-type Aerogel Cherenkov Counter (ACC) n = 1.01  1.03 depending on  –Time-Of-Flight (TOF) –Ionization loss in CDC (dE/dx) 2007/9/22Toru ijima, B-L workshop 9 Combined to form a likelihood; Use a cut on the likelihood ratio; Proton-ID performance w/ a nominal cut Eff(p) = 70% Fake(   p) = 4% Fake(K  p) = 11% Proton-ID performance w/ a nominal cut Eff(p) = 70% Fake(   p) = 4% Fake(K  p) = 11% P th (  ) = 0.99  0.57 GeV/c P th (p) = 6.6  3.8 GeV/c   p , p  0 analyses use a different cut At Super-Belle, large improvement is expected by using Ring imaging type Cherenkov detectors

 Reconstruction The  candidates are reconstructed via p  - decay channel. Selection parameters; –Angle difference between P  and IP –VTX. –Flight distance of  –Closest approach of the  daughter tracks to IP. Particle ID cut for daughter tracks. 2007/9/22Toru ijima, B-L workshop 10  selection efficiency ~ 80% Purity ~ 90% Y.Miyazaki et al., PLB632(2006)51-57 Signal MC Data Histo:  +qq MC

  p , p  0   p  (86.7fb -1 )   p  0 (153.8fb -1 ) 2007/9/22Toru ijima, B-L workshop 11 N obs = 16 N bkg = 9.1±1.7 (expected) Br (  -  p  ) < 3.0×10 -7 N obs = 70 N bkg = 52.2±7.3 (expected) Br (  -  p   ) < 6.5×10 -7 BELLE-CONF-0433 hep-ex/  signal box  =6.9±4.3  =17.8±11.1 (UL determined by an unbinned ML fit)

  154fb /9/22Toru ijima, B-L workshop 12 B-L conserving (  -   - ) B-L violating (  -   - ) Con.Vio. Eff(%) N side 55 N bkg (exp’d)1.7±0.8 N obs 10 S Br (×10 -7 )<1.3<0.70 We evaluate UL using 5  ellipse. BKG are extrapolated from 15  box assuming flat dist. S 90 : Feldman-Cousins UL of 90% CL. including systematic errors (POLE) Y.Miyazaki et al., PLB632(2006)  ellipse  MC qq MC (uds) BKG:  (~1/2) + qq (~1/2) Only a few background  Will be improved by 1/L int

LFV in  Decays Probe for 3 ⇔ 1/3 ⇔ 2 gen. mixing in the charged lepton sector. Br(  ) = O( ) x Br(  ). Enough chance to see    or   lll. The two decays have different sensitivity for different NP models.   3l, l  ll Slepton mass matrix

  l , l ,l  ’,l  0 signal data  →   →  (→  )  → ,e 535fb -1 (hep-ex/ submittedd to PLB) Br(  →  )<4.5x10 -8 (90%C.L.) Br(  → e  )<1.2x10 -7 (90%C.L.)  →e/  +  ’  401fb -1 (PLB648, 341 (2007)) Br(  → l ,l  ’,l  0 ) <(6.5-16)x %C.L. ⇒ Upper limits for LFV  decays are approaching O(10 -8 ) signal region Bkg. from  /  + initial state   →e/  +  ’   Only a few background  Will be improved by 1/L int 2007/9/22 14 Toru ijima, B-L workshop

 →lll: Background suppression Signal topology BG events electron-veto on the tag-side (e-e+e- and e-  +  -)  -conversion veto (e-e+e- and  -e+e-) m 2 miss and p miss (e-e+e-,  -  +  -, e-  +  -,  -e+e-) Bhabha (  ) ee  ( eeee ) mode   e-e+e-e-e+e- e+e-ee+e-e eeeeee Dominant bkg.  qq  Bhabha eeee  ee     qq 2007/9/22 15 Toru ijima, B-L workshop

 535fb /9/22Toru ijima, B-L workshop 16   eee Efficiency: 6.0% － 12.5% N bkg (expected) = 0 – 0.4 events No event found in the signal region Obtained upper limit (90%CL) Br<( )×10 -8 Improved by from Belle previous 90fb -1 mode U.L. of e-e+e-e-e+e- 3.6×10 -8  3.2×10 -8 e--e-- 4.1×10 -8 e+e-e+e- 2.7×10 -8 e+-e+- 2.3×10 -8 +e-e-+e-e- 2.0×10 -8 datasignal preliminary The most stringent upper limits among LFV  decays Still a few background  Will be improved by 1/L int

  lV 543fb /9/22Toru ijima, B-L workshop 17 modeBelle(158fb -1 ) ＠ 90%C.L. Belle(543fb -1      7.7   ee 7.3         ee     K*      e - K*      - K*      e - K*         2.0  ee 6.5   →      K* 0 Still a few background  Will be improved by 1/L int

 signal   /e + 2 chg. tracks  tag   /e + n  Background: , qq Continuum bkg. suppression by  flight length & R 2  2D PDF  Likelihood ratio   158fb -1 <7.3<2.0<3.0<3.1 <4.8<3.4<8.0<4.4 <7.2<1.6<1.9 <2.7<7.3<2.9 UL (x10 -7, 90%CL) Y.Yusa et al., PLB640(2006) Signal MC qq MC (uds) LNV *** * * * 2007/9/22 18 Toru ijima, B-L workshop *Still a few background  Will be improved by 1/L int

Summary for non-SM  Decay Search  →3leptons  →e ,e   →  →l→l  →l ,l  ’,l  0  →lhh’ New results this summer Upper limits of LFV  decay ▼▼ ▼ ▼▼ ▼ ▼▼ BNV 2007/9/22 19 Toru ijima, B-L workshop ULs for all LFV  decays are approaching the level

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

Interaction Region Crab crossing  =30mrad.  y*=3mm New QCS Super-KEKB Linac upgrade More RF power Damping ring New Beam pipe Increase beam currents 1.6 A (LER) / 1.2 A (HER) → 9.4 A (LER) / 4.1 A (HER) Smaller  y * 6 mm→3 mm Increase  y 0.059→>0.24(W-S) L=8x10 35 cm -2 s -1 8GeV (e+, 4.1A) 3.5GeV (e-, 9.6A)

Crab Cavity Superconducting crab cavities (1LER and 1HER) have been installed, and being tested at KEKB /9/22Toru ijima, B-L workshop

Crab Status Crab cavity installed in Jan Beam-beam tune shift (0.088) achieved at low currents. Beam current gradually increased  L=10 34 cm -2 s -1 with crab crossing by June Still need R&D/tuning to see L improvement (simulation predicts x2). 2007/9/22Toru ijima, B-L workshop 23 HER LER Crab OFF Crab ON 22mrad crossing crab crossing  y (beam-beam simulation)

24 Belle Upgrade SC solenoid 1.5T New readout and computing systems CsI(Tl) 16X 0  pure CsI (endcap) Aerogel Cherenkov counter + TOF counter  “TOP” + RICH Si vtx. det. 4 lyr. DSSD  2 pixel/striplet lyrs. + 4 lyr. DSSD Tracking + dE/dx small cell + He/C 2 H 5  remove inner lyrs. Use fast gas  / K L detection 14/15 lyr. RPC+Fe  tile scintillator 2007/9/22Toru ijima, B-L workshop

Summary B-factories provide an unique opportunity to study BNV, LNV, LFV in higher generation. The present KEKB provides 6x10 8  pairs  New results for LFV search using the full data sets are approaching to O(10 -8 ). Super-KEKB will provide x ~ statistics.  The search region will enter into O(10 -9 ) for many decays.  Good chance to see LFV  decays.  BNV can be tested too.

Backup Slides

International Collaboration: Belle 13 countries, 55 institutes, ~400 collaborators 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 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 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. 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

CP violation Precise CKM Rare decays –FCNC decays –Tauonic decays  decays –Lepton flavor violation –CPV in lepton sector Physics Targets at Super-B Using O(10 10 ) B and  (~100 x now) Search for new origin of flavor mixing and CPV.

Br~O(10 -8  9 ) at Super B factory ! T LFV Prospect             suffers from background due to ISR.

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

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