Significant differences between transverse and longitudinal polarized parton distributions are found at low energies within a light-front covariant quark model of the nucleon. These differences are due to relativistic spin effects introduced by the Melosh rotations and survive evolution to higher Q2 scales. We show that the importance of these relativistic effects can be assessed by measuring d...

Next-to-leading order QCD corrections to top quark spin correlations at hadron colliders: the reactions q ¯ q → t ¯ t(g) Abstract: Future hadron collider experiments are expected to record large to huge samples of t ¯ t events. The analysis of these data with respect to t ¯ t spin-spin correlations requires precise predictions of the production of these quark pairs in a general spin configurati...

An outline is explained for hadron-physics projects at J-PARC, which is considered to be one of the flagship facilities in hadron physics from 2008. The facility provides an intensity frontier with 50 GeV proton beam for nuclear and particle physics. It could cover a wide range of hadron physics from strongly interacting many-body systems with an extended hadronic degree of freedom, strangeness...

The COMPASS Experiment at the CERN SPS has a broad physics program focused on the nucleon spin structure and on hadron spectroscopy, using muon and hadron beams. Main objectives for the spin program with the muon beam are the direct measurement of the gluon contribution to the spin of the nucleon, semiinclusive measurements, and the measurement of the transverse spin distribution ∆Tq(x). The CO...

Hadron structure studies might be traced back to Fermi-Yang [1] and Sakata models [2]. Gell-Mann [3] and Zweig [4] proposed the quark model of hadrons. Lepton-nucleon deep inelastic scattering (DIS) [5] verified the quark structure of hadrons. However the quark revealed in DIS is found to be different from the quark as a carrier of SU(3) symmetry in Gell-Mann-Zweig model. The former is almost a...

In the case of elastic high-energy hadron-hadron scattering, the impact of the largedistance contributions on the behaviour of the slopes of the spin-non-flip and of the spinflip amplitudes is analysed. It is shown that the long tail of the hadronic potential in impact parameter space leads to a value of the slope of the reduced spin-flip amplitude larger than that of the spin-non-flip amplitud...

A behavior of imaginary and real parts of the high-energy elastic hadron scattering amplitude is examined in the diffraction region. It is shown that the interference between Coulomb and hadronic scattering at small momentum transfers and especially in the region of diffractive minimum can bring some information about the structure of the hadron spin-non-flip amplitude.

Our present information on the gluon polarisation ∆g/g is reviewed. The data from fixedtarget lepton–nucleon experiments are in context with the recent data from the RHIC polarised pp collider. The main tools to study ∆g/g in lepton–nucleon scattering are scaling violations of the g1 structure functions and longitudinal spin asymmetries in hadron production. Results from high-pT hadron pairs, i...