We study bottomonium hadroproduction in proton-antiproton collisions at the Fermilab Tevatron in the framework of the quasi-multi-Regge kinematics approach and the factorization formalism of nonrelativistic QCD at leading order in the strong-coupling constant s and the relative velocity v of the bound quarks. The transverse-momentum distributions of prompt nS-meson production measured at the Tevatron are fitted to obtain the nonperturbative long-distance matrix elements for different choices of unintegrated gluon distribution functions of the proton.

We study charmonium production at high-energy colliders (Tevatron, HERA, and LEP2) in the framework of the k T -factorization approach and the factorization formalism of non-relativistic quantum chromodynamics at leading order in the strong-coupling constant α s and the relative velocity v. The transverse-momentum distributions of direct and prompt J/ψ-meson production measured at the Fermilab Tevatron are fitted to obtain the non-perturbative long-distance matrix elements for different choices of unintegrated gluon distribution functions in the proton. Using the matrix elements thus obtained, we predict charmonium production rates in γγ, γp, and deepinelastic ep collisions including the contributions from both direct and resolved photons. The results are compared with the known ones obtained in the conventional parton model and with recent experimental data from HERA and LEP2.

We study inclusive dijet azimuthal decorrelations in proton-proton collisions at the CERN LHC invoking the hypothesis of parton Reggeization in t−channel exchanges at high energies. In the parton Reggeization approach, the main contribution to the azimuthal angle difference between the two most energetic jets is due to the Reggeon-Reggeon-particle-particle scattering, when the fusion of two Reggeized gluons into a pair of Yang-Mills gluons dominates. Using a high-energy factorization scheme with the Kimber-Martin-Ryskin unintegrated parton distribution functions and the Fadin-Lipatov effective vertices we obtain good agreement of our calculations with recent measurements by the ATLAS and CMS Collaborations at the CERN LHC.

In the framework of the relativistic quasipotential quark model the mass spectrum of baryons with two heavy quarks is calculated. The quasipotentials for interactions of two quarks and of a quark with a scalar and axial vector diquark are evaluated. The bound state masses of baryons with J P = 1 2 + , 3 2 + are computed.

We evaluate the masses of baryons composed of two heavy quarks and a strange quark, taking into account spin-dependent splittings in the framework of the potential model with the K 2 O potential ͓V. V. Kiselev, A. E. Kovalsky, and A. I. Onishchenko, Phys. Rev. D 64, 054009 ͑2001͔͒ motivated by QCD with a three-loop ␤ function for the effective charge consistent with both the perturbative limit at short distances and a linear confinement term at long distances between the quarks. The factorization of dynamics is assumed and explored in the nonrelativistic Schrödinger equation for motion in a system of two heavy quarks constituting the doubly heavy diquark and the strange quark interaction with the diquark. The limits of the approach, its justification, and uncertainties are discussed. Excited quasistable states are classified by the quantum numbers of a heavy diquark composed of heavy quarks of the same flavor.