The masses of two-gluon glueballs are studied with a semirelativistic potential model whose interaction is a scalar linear confinement supplemented by a one-gluon exchange mechanism. The gluon is massless but the leading corrections of the dominant part of the Hamiltonian are expressed in terms of a state-dependent constituent gluon mass. The Hamiltonian depends only on three parameters: the st...

The contribution of the anomalous quark-gluon interaction induced by instantons to the polarized and unpolarized gluon distributions in nucleon is estimated. It is shown that this interaction leads to negative gluon polarization in nucleon.

We consider QCD corrections to Higgs boson production through gluon-gluon fusion in hadron collisions. We compute the effects of soft-gluon emission to all orders. We present numerical results at the Tevatron and the LHC.

The solution of the plasmon problem and the subsequent development of an effective field theory approach to ultrarelativistic plasmas are reviewed. The effective lagrangians that summarize collective effects in ultrarelativistic quark-gluon and electron-photon plasmas are presented. A generalization that describes an electromagnetic plasma at all temperatures and densities is proposed. Effectiv...

The quark loop contribution to the reggeon-reggeon-gluon vertex is calculated in QCD, where the reggeon is the reggeized gluon. Compared with the vertex in the Born approximation, this contribution exhibits a new spin structure as well as the gluon loop one. A remarkable but not complete cancellation between gluon and quark contributions to this new spin structure takes place for the case of th...

A general relation between families of (n+1) gluon and n gluon eigenstates of the BKP evolution kernels in the multicolour limit of QCD is derived. It allows to construct an (n + 1) gluon eigenstate if an n gluon eigenstate is known; this solution is Bose symmetric and thus physical for even n. A recently found family of odderon solutions corresponds to the particular case n = 2.

We study the quark-antiquark-gluon techniques in SU(3) lattice QCD, for different geometries, namely angles of 0, 45, 60, 90, 120, 135 and 180 degrees, between the quark-gluon and the antiquark-gluon segments. We calculate the form of the static potential and discuss whether, or not, two-body interactions exist between the three different bodies. We also study the existence of repulsion between...

We study the quark-antiquark-gluon techniques in SU(3) lattice QCD, for different geometries, namely angles of 0, 45, 60, 90, 120, 135 and 180 degrees, between the quark-gluon and the antiquark-gluon segments. We calculate the form of the static potential and discuss whether, or not, two-body interactions exist between the three different bodies. We also study the existence of repulsion between...

We study the quark-antiquark-gluon techniques in SU(3) lattice QCD, for different geometries, namely angles of 0, 45, 60, 90, 120, 135 and 180 degrees, between the quark-gluon and the antiquark-gluon segments. We calculate the form of the static potential and discuss whether, or not, two-body interactions exist between the three different bodies. We also study the existence of repulsion between...

s-channel discontinuity of quark-quark scattering amplitude with gluon quantum numbers in the t channel and negative signature is calculated in the Regge kinematical region in the two-loop approximation. Using this dis-continuity and assuming that the Regge asymptotic behaviour is given by the Reggeized gluon contribution, we calculate the gluon trajectory in the two-loop approximation. Remarka...