Liang Zuo-tang

Hyperon polarization and single spin left-right asymmetry in inclusive production processes at high-energies

It is shown that the polarization of hyperons observed in high energy collisions using unpolarized hadron beams and unpolarized nucleon or nuclear targets is closely related to the left-right asymmetries observed in single spin inclusive hadron production processes. The relationship is most obvious for the production of the hyperons which have only one common valence quark with the projectile. Examples of this kind are given. Further implications of the existence of large polarization for a hyperon which has two valence quarks in common with the projectile and their consequences are discussed. A comparison with the available data is made. Further tests are suggested. {copyright} {ital 1997} {ital The American Physical Society}

Spin structure and longitudinal polarization of a hyperon ine+e−annihilation at high energies

Longitudinal polarizations of different kinds of hyperons produced in e + e − annihilation at LEP I and LEP II energies in different event samples are calculated using two different pictures for the spin structure of hyperon: that drawn from polarized deep inelastic lepton-nucleon scattering data or that using SU(6) symmetric wave functions. The result shows that measurements of such polarizations should provide useful information to the question of which picture is more suitable in describing the spin effects in the fragmentation processes.

Spin alignment of a vector meson in e + e − annihilation at the Z 0 pole

We calculate the spin density matrix of the vector meson produced in e+e- annihilation at Z^0 pole. We show that the data imply a significant polarization for the antiquark which is created in the fragmentation process of the polarized initial quark and combines with the fragmenting quark to form the vector meson. The direction of polarization is opposite to that of the fragmenting quark and the magnitude is of the order of 0.5. A qualitative explanation of this result based on the LUND string fragmentation model is given.

Hyperon polarization in semi-inclusive deeply inelastic lepton-nucleon scattering at high energy

We calculate the polarizations for different octet hyperons produced in the current fragmentation regions of the deeply inelastic lepton-nucleon scatterings

Longitudinal polarization of hyperon and antihyperon in semi-inclusive deep-inelastic scattering

\mu^-N \to \mu^- HX

Spin alignment of vector mesons in unpolarized hadron-hadron collisions at high energies

and

Spin alignment of the high p T vector mesons in polarized pp collisions at high energies

\nu_{\mu} N \to \mu^- HX

Hyperon polarization in nu(mu) charged current interaction at NOMAD energies

at high energy using different models for spin transfer in fragmentation processes. The results show that measurements of those hyperon polarizations should provide useful information to distinguish between different models in particular the SU(6) and the DIS pictures used frequently in the literature. We found, in particular, that measuring the polarization of

Lambda polarization and single-spin left-right asymmetry in diffractive hadron-hadron collisions

\Sigma^+

Spin alignments of vector mesons in deeply inelastic lepton-nucleon scattering

produced in these processes can give a better test to the validity of the different spin transfer models.