The tau Lepton

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Achim Stahl RWTH Aachen University Mass Origin and Supersymmetry March 6 -8 2006 Tsukuba

description

The tau Lepton. and. Flavour Violation. Mass Origin and Supersymmetry March 6 -8 2006 Tsukuba. Achim Stahl RWTH Aachen University. t -  m - n m n t. n  p e - n e. t -decays:. Lepton Number. L i = Σ # Leptons Gen i – # Antileptons Gen i. conserved in the Standard Model. - PowerPoint PPT Presentation

Transcript of The tau Lepton

Page 1: The tau Lepton

Achim StahlRWTH Aachen

University

Mass Origin and SupersymmetryMarch 6 -8 2006

Tsukuba

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Li = Σ # LeptonsGen i – # AntileptonsGen iconserved in the Standard Model

Wolfgang Pauli

n p e-e

- -

-decays:

today: many examples

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neutrinooscillations

violatelepton

number !

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-

-

W-

- -

annihilation

forbidden:

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-

-

W-

- - forbidden:

neutrino oscillation

but: energy/momentum conservation

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-

-

W-

- - forbidden:

neutrino oscillation

but: energy/momentum conservation

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-

-

W-

- - + -

Z+

-

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-

-

W-

- - 0

Z 0

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-

-

W-

- -

neutrino oscillation

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A Ui Ui = ?*

- -

Ue1 Ue2 Ue3

U1 U2 U3

U1 U2 U3

1

2

3

e

=-

-

i

W- Ui

Ui*

A Ui Ui = 0*

br ≈ 10-40

A Ui Ui f(mi2) ≈ 0*

Ue1 Ue2 Ue3

U1 U2 U3

U1 U2 U3

Ue1 U1 U1

Ue2 U2 U2

Ue3 U3 U3

1 0 00 1 00 0 1

= * * * * * * * * *

unitarity condition

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Euro Phys J C8 (1999) 513, hep-ph/9810484

for discussion see Tord Riemanns home-pagehttp://www-zeuthen.desy.de/~riemann/

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new physics breaks GIM

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new physics breaks GIM

SUSY SO(10) NPB649(2003)189 PRD68(2003)033012 10-8 10-10

SUSY HIGGS PLB549(2002)159 PLB566(2003)217 10-10 10-7

mSUGRA EPJC14(2000)319 PRD66(2002)115013 10-7 10-9

non-universal Z´ PLB547(2002)252 10-9 10-8

Heavy Maj. NR PRD66(2002)034008 10-9 10-10

Some theoretical estimates

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- - Signal:

Background:

e+e- +-

e+e- +-

- -

e+e- q q_

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currently best limits !

approaching 109 -pairs

- -

Belle 2004: < 3.1 10-7

BaBar 2005: < 6.8 10-8

BaBar

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currently best limits !

approaching 109 -pairs

- -

Belle 2004: < 3.1 10-7

BaBar 2005: < 6.8 10-8

BaBar

prel. ’03 final ‘05

(/e-tag) 5.2 % 3.8 %

(total) 9.4 %

exp. BGD (/e) 7.8 ev. 2.8 ev.

(total) 6.2 ev.

limit (10-8) < 200 < 6.8

b-factories reaching the limits at x 10-8

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sources at the LHC:

p p W

p p Z/

p p B0 X

p p B± X

p p Bs X

p p Ds X

1.7 108

8.0 108

4.0 1011

3.8 1011

7.9 1011

1.5 1012

1 year runninglow luminosity

plenty of taus !

no chance to see- -

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Try- - + -

Simulation with underlying eventlow luminosity

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Source: W

Trigger: Single-Muon L1: pT > 14 GeV HLT: pT > 19 GeV

Trigger: Di-Muon L1: pT > 3 GeV HLT: pT > 7 GeV

Looks okay

1.7 108 per year

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DS - Source

Trigger: Single-Muon L1: pT > 14 GeV HLT: pT > 19 GeV

Trigger: Di-Muon L1: pT > 3 GeV HLT: pT > 7 GeV

Trigger-Eff. only 1%

1.5 1012 per year

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Background Problem with DS source

DS 1 % br.

10-5 br.

Does anybody know of a generator for this process ?

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-

-

W-

- - + -

Z+

-

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-

-

W-

- + - -

Z+

-

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+

-

- + - +

Z+

-

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+

-

p p Z - +

Zp

p

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+

-

p p Z - +

Zp

pW

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Can we improve a few channels at LHC ?Also look for LVF in Z-decays at LHC !

LFV tau-decays Interesting search for physics beyond the S.M. (SUSY and others )

b-factories will approach 10-8