Hadronic Systems Kanchan Kamchandani

Until 1960s, all matter was believed to constitute three elementary particles: an electron, proton and neutron. Bound systems of these three particles formed various atoms, like Hydrogen, Lithium, Beryllium etc. These elements were organized in a periodic table on the bases of their regular properties. Further, as we know, these elements form more complex systems called as molecules like Eg: 2H + O-->H2O, C + 20--> C02, etc., in terms of which it has been possible to understand most of the phenomena ocurring around us. The simple picture of the existence of three elementary particles changed during 1964-1969 when the sub-structure of the proton and neutrons was discovered and it was found that these latter particles were the lightest of many other hadrons. Now, what are hadrons? They are particles which are composed of what we today know as the elementary particles; the quarks. The standard model includes 6 flavors of quarks, each of which possesses three types of "color" charge. These quarks always form colorless hadrons: mesons which are made of a quark and an antiquark or baryons which are made of three quarks. The lightest hadrons are called as the ground state hadrons (for example, proton, neutron, pion, etc.) while those with one or more quarks excited to higher energies or angular momenta are known as excited hadrons or resonances. There exist many hadrons, whose properties cannot be explained in terms of neither of these structures. However, some of them can be understood as weekly bound systems of hadrons. Such hadrons are called dynamically generated resonances since the origin of their existence is the strong (and attractive) interaction between two (or more) hadrons (see the figure below). There are more complex structures of hadrons allowed within the theory of strong interactions, like, tetraquarks, pentaquarks, glueballs, quark-qluon hybrids, etc. Many known hadrons can be understood in terms one of these structures or in terms of a mixed configuration of different structures. My research work involves studies of the properties of different hadrons and their interactions.


The Research about infinite nuclear matter Jinnu Hu

Nuclear matter is a hypothetical system of a huge number of protons and neutrons interacting by only nuclear force. The volume and number of nucleon are infinite, but the ratio is finite in this system. There are two substances which can be approximately considered as the likelihood candidates of nuclear matter. One is the neutron star in universe and the other one is the interior of the heavy nucleus around us. Through the study on infinite nuclear matter, the one of the largest object, neutron star, can be connected with the smallest one, nucleus. The nuclear force as one of the four fundamental forces in nature still has many puzzles. It provides a chance to interpret clearly about such force from the study of nuclear matter. Therefore, we study the properties of nuclear matter with nucleon-nucleon interaction in the many-body framework, such as Hartree-Fock approximation to study the characters of nuclear forces. These characters include the tensor components, the strong repulsion at short distance and so on. Furthermore, we also try to use these properties to explain the astronomical observables about neutron star.

Nuclear Many-body Theory

トップ   編集 凍結 差分 履歴 添付 複製 名前変更 リロード   新規 一覧 検索 最終更新   ヘルプ   最終更新のRSS
Last-modified: 2023-10-23 (月) 12:31:09