Name： | Goro ISHIKI | |

Affiliation： | Faculty of Pure and Applied Sciences | |

Specialty： | Physics | |

Field of Research： | String theory, field theory | |

Position： | Assistant Professor | |

Degree： | Ph.D.(science) |

Degree earning University ： | Graduate School of Science, Osaka University（March 2009） |

Starting Date： | November 1,2014 |

Mentor： | Professor Nobuyuki Ishibashi |

Laboratory： |

## Constructing string theory, a unified theory of fundamental interactions.

This world is made from tiny building blocks called fundamental particles. The most familiar examples of the fundamental particles are electrons and photons. Quarks, which compose protons or neutrons, and gravitons, which transmit the gravitational force, are also considered as the fundamental particles. These fundamental particles have interactions with each other, which can be classified to four categories: gravitational, electro-magnetic, weak and strong interactions. One of the biggest goals of particle physics is to construct a theory which can describe all the interactions in a mathematically consistent way.

The three interactions other than the gravity can be formulated within a mathematical framework called field theory. Though the field theory is a very successful and useful theory in particle physics, it is not still satisfactory since it cannot describe gravity. If one tries to formulate gravity based on the field theory, it turns out that the theory becomes mathematically inconsistent (non-renormalizable). One possibility to overcome this difficulty is given by extending the notion of point particles to strings, which have finite spatial extent. The extended theory based on this idea is called string theory and it is known that the string theory can consistently describe all the interactions at least on a few simple background geometries. Toward a complete (non-perturbative) formulation of the string theory, I am trying to understand various properties of the theory. In particular, I am studying the so-called matrix model formulation of the string theory and the gauge/gravity correspondence, which is a conjectured equivalence between field theories and string theories.