We discuss how the vacuum model of Celenza and Shakin with a squeezed gluon condensate can explain the existence of an infrared singular gluon propagator frequently used in calculations within the global colour model. In particular, it reproduces a recently proposed QCD-motivated model where low energy chiral parameters were computed as a function of a dynamically generated gluon mass. We show ...

z-If the Z0 boson is made of colored subconstituents it can be produced in pp (and pp) collisions through the subprocess gluon + gluon-) Z " + gluon. Rate is estimated from Z "-7 mixing parameter and found comparable to that of Drell-Yan process.-Events with a large PT 2' and a large PT balancing gluon should be observed at pp collider. The possibility that the weak W* and 2' bosons together wi...

The motion of quark is studied in a confining bag having central color field. The Dirac equation is solved for a quark in such bag and its energy spectrum is found. It is pointed out the possibility to take into account an interaction of constituent quark with the gluon condensation as the interaction with the color background.

I review recent results on soft gluon radiation at large angles. 1 Gribov’s legacy on soft radiation Although the major interest of Vladimir Gribov [1] in QCD was on non-perturbative aspects (notably colour confinement), his work on soft photons or soft pions emission in the pre-QCD era [2] is the basis for understanding general features of perturbative QCD dynamics. In principle soft emission ...

We construct a set of states that implement the non-Abelian Gauss’s law for QCD. We also construct a set of gauge-invariant operator-valued quark and gluon fields by establishing an explicit unitary equivalence between the Gauss’s law operator and the ‘pure glue’ part of the Gauss’s law operator. This unitary equivalence enables us to use the ‘pure glue’ Gauss’s law operator to represent the en...

The contribution of the quark-quark and quark-gluon interaction induced by instantons to the valence quark and proton spin-dependent structure functions g 1 (x, Q 2) is estimated within the instanton liquid model for QCD vacuum. It is shown, that this interaction leads to a rather large violation of the Ellis-Jaffe sum rule.

We construct a set of states that implement the non-Abelian Gauss’s law for QCD. We also construct a set of gauge-invariant operator-valued quark and gluon fields by establishing an explicit unitary equivalence between the Gauss’s law operator and the ‘pure glue’ part of the Gauss’s law operator. This unitary equivalence enables us to use the ‘pure glue’ Gauss’s law operator to represent the en...