Kobayashi Tatsuo

Superstring theory provides us with the unified description of all the interactions including gravity, and matter modes such as quarks and leptons, and the Higgs mode. Superstring theory predicts extra six dimensional compact space in addition to the four dimensional space-time. One of important points is that when we fix the background such as six dimensional compact space, which modes appear is determined, e.g. gauge bosons, generations of quarks and leptons and other modes. I have been studying particle physics and cosmology derived from superstring theory on six dimensional compact space. Four dimensional low energy effective field theory depends on geometrical aspects of six dimensional compact space within the framework of superstring theory. I have been studying which properties in particle physics originate from geometrical aspects of string compactifications, and how geometrical structures and symmetries appear in four dimensional low energy effective field theory and they control the effective theory. The vacuum expectation values of moduli fields characterize the size and shape of six dimensional compact space. Thus, the moduli fields are characteristic features of higher dimensional theory such as superstring theory. Particle physics and cosmology relevant to moduli fields give us important aspects, which may lead to indirect predictions of string compactifications. Thus, studies relevant to moduli fields are important issues in my research such as geometrical symmetries of moduli, moduli-depenence of coupling constants in the effective field theory, the moduli potential, dynamics of moduli, etc.