# Division of Theoretical Studies

At Nagoya University the foundation of ingenious research of theoretical physics was built by Prof. Shoichi Sakata and his colleagues, and various great achievements, led to the revolution of the fundamental physics that occurred in the 1970s, had been produced one after another. Among these are the Two-Meson Hypothesis which introduces μ lepton, Sakata model, which gave the foundation of the quark model, and Maki-Nakagawa-Sakata theory predicting the neutrino oscillations. These achievements culminated in the Kobayashi-Maskawa theory and further in the Standard Model of particle physics based on the gauge quantum field theory. After the Standard Model went through stringent tests of high-energy accelerator experiments, Prof. Kobayashi and Prof. Maskawa were awarded the 2008 Nobel Prize.

The standard model, which had been tested successfully through a wide variety of experiments and observations, recently became to show its flaws where the phenomena not explained with the simple standard model have been found. They are dark energy, dark matter, whose existence was established in recent precision astrophysical observations, and the neutrino oscillations found in the underground experiments. The long-waited experiments in the large hadron collider (LHC), now under operation, are expected to produce in a few years the key results to solve the question of the origin of mass of the elementary particles. It is no exaggeration to say that now the study of the fundamental theory of particles and the universe are entering the second revolutionary era after the first that produced the standard model in 1970th.

At the Division of Theoretical Studies in KMI, based on the brilliant tradition of research in the fundamental physics at Nagoya University, we aim to lead the fundamental theoretical physics with our original approach again in the period of this second revolution. The center consists of three divisions; The Theoretical Particle Physics Group studies the theory of elementary particle and explores the physics beyond the standard model. The Cosmology and Theoretical Astrophysics Group researches particle physics and cosmology to solve the problems such as the dark matter and dark energy. The String Theory and Mathematics Group investigates mathematical structures mainly for the gauge/gravity correspondence. In addition to the three divisions, Computational Theoretical Physics Laboratory carries out numerical simulation utilizing the high performance computers equipped in this institute to elucidate the evolution of the universe and the gauge dynamics of the quantum field theory. Working closely with all of these divisions and laboratory, and also in corporation with the Division of Experimental Studies, we will explore the fundamental theoretical physics in the new era.