T.Ohshima Beijing 2004 / LFV at B-Factories 1

Lepton Flavor Violation Search at B Factories

T. Ohshima (Nagoya U.)

’s LFV and New Physics’s at B-FactoryNew Data from B-Factory / e, (/e) + (0//’), 3 leptons, p/ p0, , andKs/ eKs Summary

T.Ohshima Beijing 2004 / LFV at B-Factories 2

CLEO made extensive study on ’s LFV with about 10/fb(10M ’s).Sensitivities on Br O(10-6)

Now, B-factory gets about 300 M ’s with luminosity 1034/cm2 s ever achieved. If no-BG w/10%, BrO(10-8)

Tau at B-Factory ( Belle & BaBar )

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Experiment: (e+e- ) = 0.9 nb; (e+e- BB) = 1.0 nb at (4S)(1) Properties: produced in pair; >0 ’s; ISR(initial rad.)(2) Sensitivity: For BG0, sensitivity cannot be improved linearly with 1/L 1/ L (3) Method for detection: BG Suppression

Tau at B-Factory ( Belle & BaBar )

1. look for decays in exclusive mode (low multiplicity) 2. Separation into 2-hemisphers

signal-side: 1 or 3 prong ( l , l 0, l , p, p0 / l / ’, 3 l, ) tag-side: 1-prong (Br = 80%)

3. BG (higher-order radiative Bhabha and , qq, with wrong PID) 4. Sample selection 5. Signal should have Minv=M and E=0 (EsignalCM-EbeamCM) 6. Blind analysis over signal-region7. Expect BG evaluation in signal-region 8. Blind opened and candidates obserced9. Calculation of an upper limit by Bayesian/ Feldman-Cousins or Maximum likelihood method

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New Data from Belle & BaBar1. & e Data history

Normal ordering case

for tan>1Br tan2/ MSUSY

4

Br(ee) / Br() 1/94Br()/ Br() 1/440 Br(eee) / Br(e) 1/94 Br(e)/ Br(e) 1/440

MSSM+Seesaw

e

J.Ellis, J.Hisano, M.Raidal and Y.Shimizu, PR D66 (2002) 115013

Br( ) (6x10-

7)( )2( )4

tan 60

1 TeV MSUSY

Photonic diagram

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1 (1)Belle (86.3/fb) K. Abe et al, PRL 92 (2004) 171802-1 BG: & Selection on missing quantities

pmissing vs M2missing

Minv-E

1-1 prong

98% of removed, 76% of signal survive.s

Standard employed at Belle for most of analyses.

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1 (1)

Result

E distribution

Comparison with CLEOBayesian method (s0 w/ 90% CL)

=10.8%, N=78.5x106

Br( ) < 3.4 x 10-7 at 90% CL

3region

s=0; b=54; s0(90%CL)=5.1 ev

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1 (2) eBelle (new data, 87.1/fb) K. Abe et al, Conf-contribution paper BG: & ee Selection on pmissing vs m2

missing

M_inv-E

E distribution

ResultBr(e ) < 3.8 x 10-7 at 90% CL

s = 3.75 ev (90%CL), b=20 ev = 6.5%, N=79.3x106

systematic uncertainty = 6.8%

Preliminary

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Br( ) (8x10-7)( )6( )4

2 (/e)+(0//’), 3l -> and sensitive to Higgs in SUSY

Br(3l ) / Br() 0.2Br()/ Br() 0.006Br(’ )/ Br() 0.004

tan 60

100 GeV mA

Br() : Br(3) : Br() =

Higgs mediated diagram

K.S.Babu and C. Kolda, PRL 89 (2002) 241802M. Sher, PR D66 (2002) 057301A. Dedes, J. Ellis and M. Raidal, PL B549 (2002) 159. A. Brignole and A. Rossi, hep-ph/0404211.

Enhancement of to 3(1) a colorfactor 3, (2) Yukawa-coupling (ms/m)2,(3) Phase space 3/2. In total, a factor of 10

tan2

mA

1( )4

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2 (1)(/e)+(0//’)Belle (new data,153.8/fb) K. Abe et al, Conf-contribution paper 432 BG: & qq Selection on pmissing vs m2missing

Signal MC

and masses

for tag side, mtag < 1.777 GeV/c2

E-Minv

0.0+0.4 / 0 ev 0.230.23 / 0 ev 0.150.15 / 0 ev 0.160.16 / 1 ev

2.70.7 / 5 ev 0.60.4 / 0 ev 3.1.0 / 1 ev 1.40.6 / 0 ev

expected BG / obserbed ev

90% aperture data

-0.0

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List of results

First measurements of e’ and ’

Systematics

Preliminary

2 (1)(/e)+(0//’)

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2 (2) 3l (e-e+e-,e-+-,e+--,-e-e+,+e-e-,-+-)Babar Collaboration: B. Aubert et al. PRL 92(2004) 121801Belle Collaboration: K. Abe et al. PL B589(2004) 103.

Babar (91.5/fb) ; Belle (80/fb) BG: & qq lepton identification

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.

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3 (1) pp

Result

For p(154/fb)s (@90%CL) = 10.6 ev w/ sys. (s=3.1, b=66.9 ev)=5.8%, N=140x106

p

Belle (new data, 154/fb) K. Abe et al, Conf-contribution paper 433 BG: & qq Selection on pmissing vs m2missing

Proton identification

PreliminaryFor p(87/fb)s (@90%CL) = 4.5 ev w/ sys. (s=0.16, b=15.9) =9.4%, N=79x106

M_inv-E

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3 (2) Belle (new data, 154/fb) K. Abe et al, Conf-contribution paper 433

BG: & qq Selection on pmissing vs m2missing

L-B conserving (p)

& violating (p)

E vs Minv

ResultPreliminary

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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.

Summary

Red: preliminary but contributed to this Conf. Blue: preliminary but reported in elsewhere. Black: published.

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Research results on some physics parameters:

mA vs tan plot from MSUSY vs tan plot from

mSTAU vs Br from e

e

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.