1995 Fiscal Year Final Research Report Summary
Effect of heavy neutrinos in the weak bosons' pair production
| Project/Area Number |
05640336
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
素粒子・核・宇宙線
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| Research Institution | OCHANOMIZU UNIVERSITY |
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Principal Investigator |
SUGAMOTO Akio Ochanomizu Univ.Dept.physics Professor, 理学部, 教授 (70132686)
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| Co-Investigator(Kenkyū-buntansha) |
SHIRAISHI Kiyoshi Akita J.College Economics Assoc.Prof., 商経科, 助教授 (80202117)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Heavy neutrino / Electron, positron scattering / Weak bosons' pair production / Electro weak Baryogenesis / Phase transition dynamics / Vector-like quhrk makel / ep violation / Super symaetric model |
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| Research Abstract |
1. Effects of the heavy neutrino in the 4th generation have been investigated in the e^+e^---> W^+W^- process, where 1) weak boson's 3 point formfactors, 2) differential cross sections, and 3) foreward-backward asymmetry was estimated. It has been shown that the neutrino type of Majorana or Dirac can be determined from the "threshold behavior of the scattering amplitudes", When the polarizd electron and positron beams are adopted as well as the polarization measurement of the final W' s can be performed. In the next collider energies the the heavy neutrinos' contibution to the cross sections is about 0.5%. 2. Baryogenesis at electoroweak scale has been studies using the heavy neutrinos. The lepton number generation rate has been estimated from the scattering of the neutrinos from the bubbles which appear in the development of the lstorder phase transition of our universe. Furthermore, simulation has been performed including the generation, fusion and growth effects of the bubbles, leading to the 2-3 times larger value for the produced to tallepton numbers. The observed value of the baryon number can be explained with the 100GeV and 50 GeV neutrinos at the phase transition temperature of 100K.3. CP violation effects in the weak boson's pair production processes have been studied in the model (1) with the heavy vector-like down-type quark, leading to the small value of 10^<-9>. In the supersymmetric standard model (2), however, a rather big value of 10^<-(4-5)> has been found due to the extra CP violationin the softly susy breaking term. 4. As the other baryogenesis model, the hyper-charge generation rate has been estimated in the presence of the up-type vector-like quark of 500 GeV,and the phase transition dynamics has been studied in this model. 5. Atmospheric neutrino problem has been examined in the 3 generation model of the neutrino oscillation.
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