We calculate the spin density matrix of the hadron h created via quark fragmentation in the process e − e + → q ¯ q → h + X. In the case of h = Λ the experimental data could possibly elucidate the problem of s-quark contribution to the spin of the Λ-hyperon, to be compared with the case of the proton (" spin crisis "). Generally we find that for hadrons with spin 1/2 the parton description, usi...

Abstract. The processes of the single W -production in hadron-hadron collisions are suggested for investigation of the nucleon spin. An approach is proposed for the determination of quark spin densities at low x. The lowest order electroweak radiative corrections to the observable quantities are calculated. The numerical calculations of the cross sections and the single spin asymmetries taking ...

We study weighted azimuthal single spin asymmetries in hadron-hadron scattering using the diagrammatic approach at leading order and assuming factorization. The effects of the intrinsic transverse momenta of the partons are taken into account. We show that the way in which T -odd functions, such as the Sivers function, appear in these processes does not merely involve a sign flip when compared ...

We present a phenomenological approach to the description of single transverse spin asymmetries (STSA) in inclusive hadron production. It generalizes the pQCD formalism for high energies and large pT inclusive hadron production processes, AB → C X, by incorporating quark intrinsic motion in the spin dependent quark distribution and fragmentation functions. We concentrate here on spin and k⊥ eff...

The study of two spin asymmetries in hadron-hadron collisions probes the details of fundamental particle interactions in ways infeasible to machines with unpolarized collisions. Within reach is how the proton spin is distributed among its constituents through ∆G and ∆q̄. Measuring couplings, furthering our understanding jet structure and uncovering new physics are all among the possibilities ava...

I study the effect of scalar and spin-orbit absorption potentials, in the production of a nonzero Sivers-like asymmetry in hadron-hadron high energy collisions (DrellYan and single spin asymmetries). A basic model is built for the intrinsic state of a quark in the projectile hadron. S-wave and P-wave 2-component states are considered. Before the hard event, this quark is subject to absorbing me...

Spin effects in exclusive and inclusive reactions provide an essential new dimension for testing QCD and unraveling hadron structure. Remarkable new experiments from SLAC, HERMES (DESY), and Jefferson Lab present many challenges to theory, including measurements at HERMES and SMC of the single spin asymmetries in ep→ e′πX where the proton is polarized normal to the scattering plane. This type o...

The analysing power AN is examined in the range of the Coulomb-hadron interference on the basis of the experimental data from pL = 6 GeV/c up to 200 GeV/c taking account of a phenomenological analysis at pL = 6 GeV/c and a dynamic high-energy spin model. The results are compared with the new RHIC data at pL = 100 GeV/c. The new experimental data obtained at RHIC indicate small contributions of ...

The Relativistic Heavy Ion Collider (RHIC) has brought the study of spin effects in hadronic collisions to a new energy regime. In conjunction with other experiments at facilities around the world, much can be learned from the high-energy polarized proton collisions RHIC provides, allowing the collider to serve as a powerful tool to continue to understand the rich subtleties and surprises of sp...