img Profile
Tatsuo Kobayashi
e-mail address
(Please replace "_@_" with "@")
Key Word
  • String phenomenology
  • String cosmology
  • Extra dimensional models
  • Supersymmetry
  • Flavor Mechanism

img Research Field
The standard model has been established as the theory of particle physics at the weak scale experimentally. However, it has several mysteries and puzzles inside such as the gauge and flavor structures and it also has many free parameters. Then, it is believed that there would be underlying theory to explain them. Furthermore, the standard model has no caididate for the dark matter, and also quantum gravity is outside of the target of the standard model. Thus, there must exist the more underlying theory beyond the standard model to explain them.

Superstring theory is a promising candidate for the unified theory of all the interactions including gravity and all the matter fields and scalar fields. The typical scale of superstring theory is the Planck scale, which is very high compared with the weak scale. Thus, it is quite important to study in two approaches, the top-down approach from superstring theory and the bottom-up approach with taking into account experiments, complimentarily.

  • String phenomenology
  • Superstring theory predicts six-dimensional compact space in addition to our four-dimensional spacetime. Such a compact space is quite important, because it determines the particle content in low-energy effective theory, and their quantum numbers, the flavor structure, and the strengths of their couplings. I have been studying which class of compactifications in supersting theory lead to realistic results in particle physics.

  • Superstring cosmology
  • There are lots of mysteries in the Universe. However, if superstring theory is the theory of everything in our world, it can explain such mysteries in the Universe. I have been studying cosmological aspects such as inflation models and dark matter.

  • Supersymmetry
  • Low-energy effective field theory of superstring theory can be written by supergravity theory. I have been studying which type of supergravity theory can be derived from superstring theory and its implications on particle phenomenology and cosmology.

  • Flavor
  • The flavor structure of quarks and leptons are mysterious. Why are there three generations ? Why are quark and lepton masses so hierarchical ? What is the origin of the mixing patterns ? I have been studying on such a mystery and attempting to understand them from aspects of compactifications.

    img Achievements
    • H.Ishimori, T.Kobayashi, H.Ohki, H.Okada, Y.Shimizu and M.Tanimoto,
      ``An Introduction to Non-Abelian Discrete Symmetries for Particle Physicists'', Lecture Notes in Physucs, 858 (2012) 1-227 Springer.