Lepton Flavor Violation Search at B Factories

1. Lepton Flavor Violation Search at B Factories T. Ohshima (Nagoya U.) • t’s LFV and New Physics • t’s at B-Factory • New Data from B-Factory • t mg / eg, t (m/e) + (p0/h/h’), t 3 leptons, • t pg / pp0, t Lp , and t mKs/ eKs • Summary T.Ohshima Beijing 2004 / LFV at B-Factories

2. Tau at B-Factory ( Belle & BaBar ) CLEO made extensive study on t’s LFV with about 10/fb(10M tt’s).Sensitivities on Br @ O(10-6)Now, B-factory gets about 300 M tt’s with luminosity 1034/cm2 s ever achieved. If no-BG w/e@10%, Br@O(10-8) T.Ohshima Beijing 2004 / LFV at B-Factories

3. Tau at B-Factory ( Belle & BaBar ) Experiment:s (e+e-tt) = 0.9 nb; s(e+e- BB) = 1.0 nb at U(4S)(1) Properties: produced in pair; >0 n’s; ISR(initial rad.)(2) Sensitivity: For BG0, sensitivity cannot be improved linearly with 1/L 1/L . (3)Method for detection: BG Suppression • look for decays in exclusive mode (low multiplicity) • Separation into 2-hemisphers signal-side: 1 or 3 prong ( lg, lp0, lh, pg, pp0 / lh / h’, 3 l, Lp ) tag-side: 1-prong (Br = 80%) • BG (higher-order radiative Bhabha and mm, qq, tt with wrong PID) • Sample selection • Signal should have Minv=Mt and DE=0 (EsignalCM-EbeamCM) • Blind analysis over signal-region • Expect BG evaluation in signal-region • Blind opened and candidates obserced • Calculation of an upper limit by Bayesian/ Feldman-Cousins • or Maximum likelihood method T.Ohshima Beijing 2004 / LFV at B-Factories

4. New Data from Belle & BaBar1. t mg & eg Data history MSSM +Seesaw Photonic diagram Br(tmg) @ (6x10-7)()2()4 tanb 60 1 TeV MSUSY J.Ellis, J.Hisano, M.Raidal and Y.Shimizu, PR D66 (2002) 115013 for tanb>1 Br \ tan2b / MSUSY4 Br(tmee) / Br(tmg) @ 1/94 Br(tmmm)/ Br(tmg) @ 1/440 Br(teee) / Br(teg) @ 1/94 Br(temm)/ Br(teg) @ 1/440 mg eg Normal ordering case T.Ohshima Beijing 2004 / LFV at B-Factories

5. 1-1 prong 1 (1) t mg Belle (86.3/fb)K. Abe et al, PRL 92 (2004) 171802-1  BG:gtt & gmm  Selection on missing quantities Standard employed at Belle for most of analyses. 98% of tt removed, 76% of signal survive.s Minv-DE pmissing vs M2missing T.Ohshima Beijing 2004 / LFV at B-Factories

6. DE distribution 1 (1) t mg 3s region eW=10.8%, Ntt=78.5x106 Result Br(t mg ) < 3.4 x 10-7 at 90% CL Bayesian method (s0 w/ 90% CL) Comparison with CLEO s=0; b=54; s0(90%CL)=5.1 ev T.Ohshima Beijing 2004 / LFV at B-Factories

7. DE distribution 1 (2) t eg Belle (new data, 87.1/fb) K. Abe et al, Conf-contribution paper  BG:gtt & gee  Selection on pmissing vs m2missing M_inv-DE s= 3.75 ev (90%CL), b=20 ev eW = 6.5%, Ntt=79.3x106 systematic uncertainty = 6.8% Preliminary Result Br(t eg ) < 3.8 x 10-7 at 90% CL T.Ohshima Beijing 2004 / LFV at B-Factories

8. 2 t (m/e)+(p0/h/h’), t 3l t->mh and mmm sensitive to Higgs in SUSY Br(tmh) @ (8x10-7)( )6( )4 tanb 60 100 GeV mA Higgs mediated diagram tan2b Enhancement of tmh to t3m (1) a colorfactor 3, (2) Yukawa-coupling (ms/mm)2, (3) Phase space 3/2. In total, a factor of ~10 Br(tmh) : Br(t3m) : Br(tmg) = 8 : 1.5 : 1 1 ( )4 Br(t3l ) / Br(tmh) @ 0.2 Br(tmp0)/ Br(tmh) @ 0.006 Br(tmh’ )/ Br(tmh) @ 0.004 mA K.S.Babu and C. Kolda,PRL 89 (2002) 241802 M. Sher, PR D66 (2002) 057301 A. Dedes, J. Ellis and M. Raidal, PL B549 (2002) 159. A. Brignole and A. Rossi, hep-ph/0404211. T.Ohshima Beijing 2004 / LFV at B-Factories

9. 2 (1) t (m/e)+(p0/h/h’) Belle (new data,153.8/fb) K. Abe et al, Conf-contribution paper 432  BG:gtt & qq  Selection on pmissing vs m2missing for tag side, mtag< 1.777 GeV/c2 expected BG/ obserbed ev 0.0+0.4/ 0 ev 0.230.23/ 0 ev 0.150.15/ 0 ev 0.160.16/ 1 ev -0.0 ppp and pphmasses 90% aperture data DE-Minv 2.70.7/ 5 ev 0.60.4/ 0 ev 3.1.0/ 1 ev 1.40.6/ 0 ev Signal MC T.Ohshima Beijing 2004 / LFV at B-Factories

10. 2 (1) t (m/e)+(p0/h/h’) First measurements of eh’ and mh’ Preliminary List of results Systematics T.Ohshima Beijing 2004 / LFV at B-Factories

11. 2 (2) t 3l (e-e+e-,e-m+m-,e+m-m-,m-e-e+,m+e-e-,m-m+m-) Babar (91.5/fb) ; Belle (80/fb)  BG:tt & qq lepton identification Babar Collaboration: B. Aubert et al. PRL 92(2004) 121801 Belle Collaboration: K. Abe et al. PL B589(2004) 103. BaBar Belle Since the signal-region is not dominated by BG yet, sensitivity will be improved still proportional to accumulated luminosity. Therefore, in this year or next year, the sensitivity of 10-8 will be realized. T.Ohshima Beijing 2004 / LFV at B-Factories

12. Belle (new data, 154/fb) K. Abe et al, Conf-contribution paper 433  BG:gtt & qq  Selection on pmissing vs m2missing  Proton identification 3 (1) t pg, pp0 M_inv-DE pp0 Result Preliminary For pg (87/fb) s (@90%CL) = 4.5 ev w/ sys. (s=0.16, b=15.9) e=9.4%, Ntt=79x106 For pp0(154/fb) s (@90%CL) = 10.6 ev w/ sys. (s=3.1, b=66.9 ev) e=5.8%, Ntt=140x106 T.Ohshima Beijing 2004 / LFV at B-Factories

13. 3 (2) t-Lp-, Lp- Belle (new data, 154/fb) K. Abe et al, Conf-contribution paper 433  BG:tt & qq  Selection on pmissing vs m2missing L-B conserving t-(pp-)p- & violating t-(pp+)p- Preliminary Result DE vs Minv T.Ohshima Beijing 2004 / LFV at B-Factories

14. Summary Sensitivities are improved by a factor of ten or more compared to previous ones, based on at most a quarter of billions of tau events or less. Now, B factories give us sensitivity that, for the first time, enable us to seek for new physics in Lepton Flavor Violation in tau-decay. Red: preliminary but contributed to this Conf. Blue: preliminary but reported in elsewhere. Black: published. T.Ohshima Beijing 2004 / LFV at B-Factories

15. Research results on some physics parameters: MSUSY vs tanb plot from t mg mA vs tanb plot from t mh mSTAU vs Br from t mg/ eg mg eg Belle and BaBar have now about a half of billions of tau events, 300/fb. Sensitivity on LFV gets soon to be 10-8 level, and research region for new physics is getting expand. We can expect some interesting results. T.Ohshima Beijing 2004 / LFV at B-Factories