K Meson Covariant Nature Of The Dynamics And Its Quasi-particle Model

Since the kaons were found in cosmic rays in 1944, lots of fundamental laws of microscopic world has been revealed via studying the properties of kaons. For instance, the conservation and violation of CP, breaking and restoration of the chiral symmetry, etc. They are all intimately related to the production,decay and annihilation of kaons. Strangeness production experiments were performed in the early 80s at the LBL in Berkeley by first time. In the middle of 90s the whole field obtained a significant push when the KaoS and the FOPI collaborations at GSI started to deliver high precision data for kaon and antikaon production in heavy ion systems.The heavy ion collision is, after all, an unique way to produce kaon mesons on the earth. These particles generated in the collision process must feel interaction coming from the environment which is drastically complicated. Such influence coming from environment is called medium effect.In the present paper, we give a brief review of the work studying the Kaon production in heavyion collisions at intermediate and high energy. In the theoretical part, our main attention is paid on the covariant Kaon dynamics model. The collective flows of positively charged kaon and the Lambda hyperon associated produced with Kaon are studied in the framework of the dynamics. The results indicate that the rapidity distribution of K+ mesons is mainly from the contribution of the N-△and N-N channel. This means that the delta resonance state plays a predominantly important role for the K+subthreshold production..In the end, the effective mass and energy of Kaon in dense and hot nuclear matter is studied. Our special attention is paid on the comparison of various definitions of quasi-particle model of Kaons used in transport theories. The effective mass of Kaon defined in popular mean field theory increases with increasing of the density of nuclear matter, while the quantity used in covariant Kaon dynamics decreases with the density increasing. The properties of mean field which acting on Kaon by hot and dense nuclear matter depends not only on the form of quasiparticle model of Kaons, but on the motion of nucleons around it.