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4 th Generation Leptons in Minimal Walking Technicolor Theory Matti Heikinheimo University of Jyväskylä. Background: What is technicolor?. In SM, electroweak symmetry is broken by the Higgs field Hierarchy problem: Solution: Break electroweak symmetry dynamically
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4th Generation Leptons in Minimal Walking Technicolor Theory Matti Heikinheimo University of Jyväskylä
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
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
Walking behaviour of the coupling constant as a function of momentum
Minimal Walking Technicolor Model • Fundamental techniquarks: needed for walking • → Too large contributions to the S parameter • Adjoint techniquarks • → Need only
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 ,
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
The Lagrangian: where , and mass matrix eigenvalues → Mass eigenstates , where Neutral current Charged current
Decay fractions of the Higgs boson in the standard model and in MWTC