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We give a brief overview of the kinetic theory for spin-1/2 fermions in Wigner function formalism. The chiral and spin kinetic equations can be derived from equations for Wigner functions. A general Wigner function has 16 components which satisfy 32 coupled equations. For massless fermions, the number of independent equations can be significantly reduced due to the decoupling of left-handed and right-handed particles. It can be proved that out of many components of Wigner functions and their coupled equations, only one kinetic equation for the distribution function is independent. This is called the disentanglement theorem for Wigner functions of chiral fermions. For massive fermions, it turns out that one particle distribution function and three spin distribution functions are independent and satisfy four kinetic equations. Various chiral and spin effects such as chiral magnetic and vortical effects, the chiral separation effect, spin polarization effects can be consistently described in the formalism. [ABSTRACT FROM AUTHOR]

Spin transfer in high energy fragmentation process is determined by the hadronization mechanism and spin structure of hadrons. It can be studied by measuring the polarizations of hyperons and/or vector mesons in e+e- annihilation, in the current fragmentation region of polarized deeply inelastic lN-scatterings, and high pT-jets in polarized pp-collisions. Theoretical calculations have been made using different models. In this talk, I will briefly summarize the main features of the models the results obtained and the comparison with available data, They can be used for future tests by experiments. [ABSTRACT FROM AUTHOR]

Recent measurements, in particular those on Λ polarization and spin alignment of vector mesons in e[SUP+] e[SUP-] annihilation at LEP, and those on the azimuthal asymmetry at HERA, have attracted much attention on the spin effects in high energy fragmentation processes. In this talk, we make a brief introduction to the different topics studied in this connection and a short summary of the available data. After that, we present a short summary of the main theoretical results that we obtained in studying these different topics. The talk was mainly based on the publications [5-9] which have been finished in collaboration with C.Boros, Liu Chun-xiu and Xu Qing-hua. [ABSTRACT FROM AUTHOR]

We present the results for the polarizations of different octet hyperons produced in the current fragmentation regions of μ[SUP-] N or ν[SUBμ]N deep-inelastic scatterings using different models for spin transfer in fragmentation processes. We found that measuring the polarization of ∑[SUP+] produced in these processes can give a good test to the validity of the different spin transfer models. Measuring P[SUB∑[SUP+](T)] in transversely polarized case should) be able to give an useful check whether in high-energy fragmentation process the polarization transfer mechanisms are the same for both the longitudinally polarized and transversely polarized cases. A comparison with the existing data is made. [ABSTRACT FROM AUTHOR]

The recent data on the polarization of vector meson at LEP show that the vector mesons favor the helicity zero state. We calculate the helicity density matrix of vector meson which contains a polarized fragmenting quark by adding the spin of the fragmenting quark and that of the antiquark created in the fragmentation. The data at LEP imply a significant polarization for the antiquark in the opposite direction as that of the fragmenting quark. We extend the calculations to other reactions and make predictions for vector mesons in deeply inelastic lepton-nucleon scatterings and polarized pp collisions. [ABSTRACT FROM AUTHOR]

It has been realized for quite a long time that single-spin experiments, in which one of the colliding objects is transversely polarized, can be helpful in studying the properties of strong interaction in general and in testing quantum chromodynamics (QCD) in particular. Striking effects have been observed in the past few years which deviate drastically from the expectation of the perturbative QCD parton model. These effects have received much attention. New experiments of the similar type are underway and/or planned. Different theoretical attempts have been made to understand these effects. In this review, the special role played by singly polarized high-energy hadron-hadron collisions in high energy spin physics is emphasized. Characteristics of the available data for inclusive hadron productions are briefly summarized. Different theoretical approaches for such processes are reviewed with special attention to a nonperturbative model which explicitly takes the orbital motion of the valence quarks and hadronic surface effects into account. The connection between such asymmetries and hyperon polarization in unpolarized reactions is discussed. An example of the possible application of such experimental results in other processes is given. [ABSTRACT FROM AUTHOR]