4th Generation Leptons in

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4th Generation Leptons in Minimal Walking
Technicolor Theory Matti Heikinheimo University
of Jyväskylä
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Background What is technicolor?

• In SM, electroweak symmetry is broken by the
  Higgs field
• Hierarchy problem
• Solution Break electroweak symmetry dynamically
• Technicolor a new strongly interacting sector
  accounts for EWSB

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Walking Technicolor

• To get SM fermion masses, we need another new
  interaction at some high scale
• This gives four-fermion vertices between SM
  fermions and techniquarks
• ? Flavour changing neutral currents
• Need walking dynamics to suppress the FCNCs

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Walking behaviour of the coupling constant as a
function of momentum
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Minimal Walking Technicolor Model

• Fundamental techniquarks needed for
  walking
• ? Too large contributions to the S parameter
• Adjoint techniquarks
• ? Need only

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New particles , , in the adjoint
representation of We have added three new weak
doublets ? the model suffers from Witten
anomaly Cure the anomaly add one more weak
doublet ? 4th lepton generation ,
, Neutrino mass matrix allows
the neutrino to have a general mass structure ?
Two Majorana neutrinos ,
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Phenomenology of the 4th generation leptons

• The phenomenology of the 4th lepton generation
  has been studied, but usually with 4th QCD quark
  generation
• MWTC adds only the 4th generation leptons but no
  QCD quarks
• We also allow the new neutrino to have a general
  mass structure

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The Lagrangian where ,
and mass matrix eigenvalues ? Mass
eigenstates ,
where Neutral current Charged current
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Decay fractions of the Higgs boson in the
standard model and in MWTC