Lambda and Lambda-bar Polarization in Lepton Induced Processes

The study of the longitudinal polarization of Lambda and Lambda-bar hyperons produced in polarized deep inelastic scattering, neutrino scattering, and in Z0 decays allows to access the spin dynamics of the quark fragmentation process. Different phenomenological spin transfer mechanisms are considered and predictions for the Lambda and Lambda-bar longitudinal polarization in various processes using unpolarized and polarized targets are made. Current and future semi-inclusive deep inelastic scattering experiments will provide soon accurate enough data to study these phenomena and distinguish between various models for the spin transfer mechanisms.Comment: 17 pages, LaTex with epsfig.sty, including 10 figures One reference adde

Gluon Polarization from Correlated High-p_T Hadron Pairs in Polarized l - N Scattering

We propose to access the gluon polarization $\Delta G$ by measuring the cross section spin-asymmetry in semi-inclusive polarized lepton -- nucleon scattering. The photon-gluon fusion sub-process will be tagged by detecting high-$p_T$ correlated hadron pairs in the forward hemisphere. Selecting oppositely charged kaon pairs will allow to suppress the background coming from gluon radiation.Comment: 6 pages, 3 eps figures, aipproc.cls and aipproc.sty include

Globally Polarized Quark-gluon Plasma in Non-central A+A Collisions

Produced partons have large local relative orbital angular momentum along the direction opposite to the reaction plane in the early stage of non-central heavy-ion collisions. Parton scattering is shown to polarize quarks along the same direction due to spin-orbital coupling. Such global quark polarization will lead to many observable consequences, such as left-right asymmetry of hadron spectra, global transverse polarization of thermal photons, dileptons and hadrons. Hadrons from the decay of polarized resonances will have azimuthal asymmetry similar to the elliptic flow. Global hyperon polarization is predicted within different hadronization scenarios and can be easily tested.Comment: 4 pages in RevTex with 2 postscript figures, an erratum is added to the final published versio

Polarization probes of vorticity in heavy ion collisions

We discuss the information that can be deduced from a measurement of particle (hyperon or vector meson) polarization in ultrarelativistic nuclear collisions. We describe the sensitivity of polarization to initial conditions, hydrodynamic evolution and mean free path, and find that the polarization observable is sensitive to all details and stages of the system's evolution. We suggest that an experimental investigation covering production plane and reaction plane polarizations, as well as the polarization of jet-associated particles in the plane defined by the jet and particle direction, can help in disentangling the factors contributing to this observable. Scans of polarization in energy and rapidity might also point to a change in the system's properties.Comment: In press, Phys.Rev.C. One new figure, text streamlined and edited, physics conclusions and reasoning not change

Gluon polarization from correlated high-pT hadron pairs in polarized electro-production

We propose to measure the gluon distribution function Delta G(eta) at eta < 0.2 via pseudo jet production in polarized fixed target lepton nucleon scattering at typical lepton beam energies of 200 GeV. The measurement of the spin-asymmetry for the production of correlated charge conjugated hadrons of opposite transverse momentum can be directly related to Delta G(eta) through the photo-gluon fusion process. Wa also present a numerical analysis of the accuracy which can be obtained for different flavors and kinematics of the observed hadron pair.Comment: 18 pages, 6 eps figure

Future physics with polarized ep-colliders

We discuss some of the physics opportunities at polarized ep-colliders. Recent studies for polarized ep-colliders include HERA, EIC and THERA.Comment: 7 pages, 6 figures, Invited talk presented at the ``International Workshop on the Spin Structure of the Proton and Polarized Collider Physics'', ECT, Trento, Italy, July 23-28, 200

Evolution of twist-3 multi-parton correlation functions relevant to single transverse-spin asymmetry

We constructed two sets of twist-3 correlation functions that are responsible for generating the novel single transverse-spin asymmetry in the QCD collinear factorization approach. We derive evolution equations for these universal three-parton correlation functions. We calculate evolution kernels relevant to the gluonic pole contributions to the asymmetry at the order of $\alpha_s$. We find that all evolution kernels are infrared safe as they should be and have a lot in common to the DGLAP evolution kernels of unpolarized parton distributions. By solving the evolution equations, we explicitly demonstrate the factorization scale dependence of these twist-3 correlation functions.Comment: 28 pages, 17 figures, new materials and references adde

Production mechanisms and single-spin asymmetry for kaons in high energy hadron-hadron collisions

Direct consequences on kaon production of the picture proposed in a recent Letter and subsequent publications are discussed. Further evidence supporting the proposed picture is obtained. Comparison with the data for the inclusive cross sections in unpolarized reactions is made. Quantitative results for the left-right asymmetry in single-spin processes are presented.Comment: 10 pages, 2 Postscript figure