In this talk, I focus on the quark-gluon structure of hadrons probed using high-energy hadron beams. I start with a brief review on recent major achievements in measuring parton distributions of the nucleon, pion, and kaon, with hadron facilities at CERN and FNAL. Then I discuss a number of outstanding questions and interesting physics issues in the field, and point out their intellectual impac...

We derive, an expression for the average multiplicity for an inclusive experiment a + b +c + X, where a, b, and c are hadrons and c is detected with a large transverse momentum. If EC is the energy of c in the center-of-mass of aandb, wefind &/4, the last term is absent. C e+eand Ch are related to the av...

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...

QCD is the accepted (that is, the effective) theory of the strong interaction; studies at colliders are no longer designed to establish this. Such studies can now be divided into two categories. The first involves the identification of observables which can be both measured and predicted at the level of a few percent. Such studies parallel those of the electroweak sector over the past fifteen y...

We review the recent applications of various parton models, to the problem of hadron-hadron scattering at large momentum transfers. Models which allow direct parton-parton interactions as well as those that do not are considered. Predictions for the structure of hadronic final states (whether or not transverse jets exist), associated multiplicities, and the s and t dependencies of inclusive and...

We show how the transverse polarization of a quark initiating a jet can be probed by the azimuthal distribution of two hadrons (of large z) in the jet. This permits a twist 2 asymmetry in hard processes when only one of the initial particles is polarized transversely. Applications to hadron-hadron and lepton-hadron scattering are discussed.

We compute the virtual next-to-leading corrections to the impact factors or offshell coefficient functions in the high-energy limit. When combined with the known real corrections, these results will provide the complete NLO corrections to the impact factors, which are necessary to use the BFKL resummation at NLL for jet production at both lepton-hadron and hadron-hadron colliders.

We show that measurements of single-spin asymmetries (SSAs) in charged current weak interaction processes such as deep inelastic neutrino scattering on a polarized target and inclusive W production in polarized hadron-hadron collisions discriminate between the two fundamental QCD mechanisms (the Sivers and Collins effects) which have been proposed to explain such time-reversal-odd asymmetries. ...