Although we know that hadrons (nucleons and mesons) are governed by Quantum Chromodynamics (QCD) and are made of quarks and gluons, the problems have not been solved concerning the very fundamental questions such as how hadrons are formed by QCD, what the structure of hadrons are like and, perhaps most importantly, how the mass of hadrons are generated from the interactions of quarks and gluons.
To solve these problems, we study the exotic hadrons which have been discovered in modern accelerator facilities such as KEK, Spring-8, J-PARC (Japan) and BES (China). They are the new type of hadrons and are expected to contain many quarks than the already known hadrons. The understanding of these particles is the key to solving the above questions.
Key wards: Exptoc hadrons, QCD, Quarks, Gluons, Pions, Nucleons, Chiral symmetry, Mass generation