Modern Physics Letters A

The 1992–1995 running of the Fermilab Tevatron (the so-called Run I) ended with many important physics goals accomplished, including the discovery of the top quark, and the anticipation of many further questions to be answered in the future. After many upgrades to the detector and to the accelerator complex, Run II began in April 2001. First results obtained by the Collider Detector at Fermilab (CDF) collaboration from the analysis of early Tevatron Run II data are reported here. They fall into two categories: a number of measurements have been performed with the primary goal of establishing detector performance and physics potential. Another set of measurements make use of completely new capabilities of the upgraded detector, thus allowing for competitive results with a modest amount of integrated luminosity.

The recently obtained solutions of Dirac equation in the confining SU(3)-Yang–Mills field in Minkowski spacetime are applied to describe the energy spectra of quarkonia (charmonium and bottomonium). The nonrelativistic limit is considered for the relativistic effects to be estimated in a self-consistent way and it is shown that the given effects are extremely important for both the energy spectra and the confinement mechanism.

We investigate the Kepler problem using a symplectic structure consistent with the commutation rules of the noncommutative quantum mechanics. We show that a noncommutative parameter of the order of 10^-58m² gives observable corrections to the movement of the solar system. In this way, modifications in the physics of smaller scales imply modifications at large scales, something similar to the uv/ir mixing.

We argue that the Born–Infeld solution on the D9-brane is unstable under inclusion of derivative corrections to Born–Infeld theory coming from string theory. More specifically, we find no electrostatic solutions to the first-order corrected Born–Infeld theory on the D9-brane which give a finite value for the Lagrangian.

We analytically calculate the topological charge of general noncommutative U(N) instantons using the Corrigan's identity and find that the result is exactly the instanton number k, which appears in the noncommutative ADHM construction as the dimension of the vector space V. This result coincides with the corresponding fact in the commutative case.

We consider the lightest Kaluza–Klein particle in universal extra dimensions (UED) to be a possible candidate for cold dark matter (CDM). We compute the relic densities for such Kaluza–Klein dark matter. This is done by first solving Boltzmann equation numerically to obtain freeze-out temperature and the ratio of number density and entropy density, for different masses. The relic densities (Ωh²) are then computed to find their variation with CDM masses. These calculations are performed considering two coannihilation channels namely B¹ B¹ → e⁺e^- and B¹ B¹ → qq.

We propose a new Doubly Special Relativity theory based on the generalization of the κ-deformation of the Poincaré algebra acting along one of the null directions. We recall the quantum Hopf structure of such deformed Poincaré algebra and use it to derive the phase space commutation relations. As in the DSR based on the standard quantum κ-Poincaré algebra we find that the spacetime is noncommutative. We investigate the fate of the properties of Special Relativity in the null basis: the split of the algebra of Lorentz and momentum generators into kinematical and dynamical parts, the action of the kinematical boost M^+-, and the emergence of the two-dimensional Galilean symmetry.