Lepton Number
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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. today: many examples. Wolfgang Pauli. n t. n m. Neutrino Oscillations. neutrino oscillations violate lepton number !. annihilation. - PowerPoint PPT Presentation
Transcript of Lepton Number
Li = Σ # LeptonsGen i – # AntileptonsGen iconserved in the Standard Model
Wolfgang Pauli
n p e-e
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-decays:
today: many examples
neutrinooscillations
violatelepton
number !
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W-
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annihilation
forbidden:
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W-
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neutrino oscillation
but: energy/momentum conservation
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W-
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neutrino oscillation
but: energy/momentum conservation
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W-
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Z+
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W-
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Z 0
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W-
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neutrino oscillation
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W-
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Ui
Ui
Euro Phys J C8 (1999) 513, hep-ph/9810484
for discussion see Tord Riemanns home-pagehttp://www-zeuthen.desy.de/~riemann/
new physics breaks GIM
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
currently best limits !
approaching 109 -pairs
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Belle 2004: < 3.1 10-7
BaBar 2005: < 6.8 10-8
BaBar
currently best limits !
approaching 109 -pairs
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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
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- -
Try- - + -
Simulation with underlying eventlow luminosity
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
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
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-
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Z+
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W-
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Z+
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Z+
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p p Z - +
Zp
p
+
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p p Z - +
Zp
pW
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
