Yasue Laboratory For Elementary Particle Theory 

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The main subject is to clarify various properties of quarks and leptons described by their unified pictures based on unification of the quark-lepton interactions and by their substructure based on compositeness of the quark-lepton states. Currently studied are possible forms of new interactions.and possible types of other fundamental particles than quarks and leptons including their subconstituents as the extension of the Glashow-Weinberg-Salam model for the standard quark-lepton physics. Also focused on are their phenomenological implications in various high-energy experiments such as p_pbar.gif (878 ???) collisions at FNAL and ep collisions at HERA.  Future planned collisions such as those at LHC, CLIC and JLC. The previously studied works have been published in several journals, which are listed as the publication list. The recent results are summarized as new results.

Our laboratory has received and will receive financial support from  the Ministry of Education, Culture, Sports, Science, and Technology, Japan, supplied by  ."Grants-in-Aid for Scientific Research":

  • Grants-in-Aid for Scientific Research on Priority Areas A
    "Neutrino Oscillations and Their Origin" (2000-2001)
  • Grants-in-Aid for Scientific Research on Priority Areas B
    "Superstring Theory and Dynamics of Field Theory" (2001-2006)

Subjects summarized:

  • Weak interactions of quarks and leptons and their compositeness

    The symmetric behavior of quarks and leptons that manifests itself in weak interactions was described as the manifestation of effects caused by more fundamental particles,
  • Weak interactions of quarks and leptons and the anomalies in neutral current interactions

    The systematic analyses and predictions on the anomalies of neutral current interactions were performed.

  • Compositeness of quarks and leptons implied by an SO(10) unified model

    A new model was proposed to describe composite quarks and leptons in accord with the SO(10) group structure.

  • Mass scales in an SO(10) unified model of quarks and leptons

    The mass scales at the spontaneous breakdown the SO(10) symmetry are determined by the stability of the Higgs potential. And applications to quark-lepton physics were described.

  • Observable effects due to quark-lepton compositeness

    Physics of composite quarks and leptons was discussed as possible observed effects in experiments, which appeared as deviations of the standard model predictions due to their finite sizes.

  • The Nambu-Goldstone mechanism for quark-lepton compositeness

    The Nambu-Goldstone mechanism in supersymmetric theories were suggested as the mass generation mechanism of light quarks and leptons. Especially, mass formula of Nambu-Goldstone fermions were derived as the supersymmetric version of the Dashen formula..

  • Masses of quarks and leptons and nonlinear interactions

    Detailed calculations of quark-lepton masses were performed by adopting nonlinear interaction of the Nambu-Jona-Lasinio type as explicit mechanism of creating composites.

  • Extra weak bosons and charge-commutation relations

    Sum rules of masses of weak bosons including extra weak bosons were derived from commutation relation of weak charges in the electroweak SU(2)xU(1) model.

  • Mass protection mechanisms and mass hierarchies of quarks and leptons

    The interplay of chiral symmetries and supersymmetry as mass protection mechanisms was applied to construct supersymmetric models for quarks and leptons exhibiting mass hierarchies.

  • Compositeness of extra weak bosons and their phenomenology

    Excited weak bosons were introduced as matter fields, which were related to weak bosons as gauge fields. The derived interactions were applied to predict possible physics of extra weak bosons at image54.gif (883 ???) and p_pbar.gif (878 ???) collisions.

  • Masses of quarks and leptons and supersymmetric quantum chromodynamics

    A possible mechanism of generating light composite fermions was suggested by utilizing Nambu-Goldstone supermultiplets in supersymmetric quantum chromodynamics (SQCD). The symmetry breaking patterns were clarified in SQCD with N"flavor">N"color" based on an effective lagrangian approach of the Veneziano-Yankielowicz type. Some of these breakings produced Nambu-Goldstone supermultiplets including quark-lepton fields, whose low-energy interactions were thus computed by the effective lagrangian. The explicit breaking terms of chiral symmetries and supersymmetry were also included in the effective lagrangian to predict quark-lepton masses. The relation of symmetry breaking patterns obtained by our research to those conjectured by Dr.Seiberg is currently studied.

  • Compositeness and "elementariness"

    Composite weak bosons were pointed out to disguise as fundamental gauge particles at low-energies below compositeness scale. Also discussed is the similar phenomenon in QCD with three flavors, where octet vector bosons were regarded as octet color massive gluons and the same procedure was applied to extra weak bosons in the QCD with the SU(2) "color",

  • Properties of strange matter

    The relationship of mass number and electric charge of strange matter was discussed to derive mass formula, which was applied to the candidate events due to strange matter.

  • Radiatively generated neutrino masses

    Neutrinos are kept massless at the tree level. Their masses are radiatively generated by one loop diagrams. 1)The model is extended to include the fourth hypothetical neutrino called "sterile neutrino" that is used to accont for oscillations of the electron neurtinos comming from the Sun.2)This radiative mechaniism is naturally incorporated in models based on SU(3)LXU(1)N and the suggested physics on creation of neutrino mass is examined.

  • CP-violation in neutrinos

    New sources of CP-violation arise from complex masses of neutrinos and are should be clarified.

  • Properties of neutrino oscillations compatible with the observation

    Constraints on flavor neutrino masses are generally derived for large neutrino mixing and neutrino  mass hierarchiy..

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