Modern Physics Letters A

The classification of scalar and vector mesons is reviewed within the framework of the Resonance-Spectrum Expansion (RSE). This method allows a simple and straightforward description of non-exotic meson–meson scattering, incorporating the effects of quark confinement and OZI-allowed decay in a fully nonperturbative way. Results for resonances and bound states are compared to experiment, on the basis of computed pole positions and cross-sections. New predictions for open-charm and -bottom scalar mesons are presented.

Concretely, observed vector states for and are reproduced, and others are predicted. In the light scalar sector, the now established two nonets, one below 1 GeV and one in the region 1.3–1.5 GeV, are easily described, through the appearance of extra poles in the S-matrix. The recently found (2317) meson is accurately reproduced by the same mechanism, as a quasi-bound state in the coupled system.

In S-wave Dπ and Bπ scattering, new resonances are foreseen close to threshold, i.e. a at 2.16±0.05 GeV some 250 MeV wide, and a at 5.47±0.05 GeV with a width of about 50 MeV. Additional predictions concern the existence of and scalar mesons, stable with respect to OZI-allowed decay to BK and BD, respectively, namely at 5.61±0.05 GeV resp. 6.64±0.05 GeV.

We summarize the results on the high energy behavior of quark–antiquark exchange in γ*γ* elastic scattering. The ladder diagrams, summed in the double logarithmic approximation, provide a perturbative QCD model for secondary reggeon exchange.

A mechanism of formation of a planet from a gaseous cloud and dust is proposed. The particles of the clouds are combined into clusters and the gravitational contraction of the system is modeled using central gravitational field. Initially the clusters are randomly distributed in the space, and during the contraction process they form hollow spherical layers. The thermodynamic approach considers each cluster as a volume comprising an initial number of the particles to give the temperature of the layers. This method has been used to model the formation of the Earth at early stages. Our results demonstrate that the gravitational contraction leads to quantization of the structure and formation of spherical shells. Particularly, the Earth consists of at least three spherical layers of high density.

The cosmological constant combined with Planck's constant and the speed of light implies a quantum of mass of approximately 2×10^-65g. This follows either from a generic dimensional analysis, or from a specific analysis where the cosmological constant appears in 4D spacetime as the result of a dimensional reduction from higher-dimensional relativity (such as 5D induced-matter and membrane theory). In the latter type of theory, all the particles in the universe can be in higher-dimensional contact.

Motivated by the recent experimental evidence of the exotic B=S=+1 baryonic state Θ (1540), we examine the older existing data on K⁺N elastic scattering through the time delay method. We find positive peaks in time delay around 1.545 and 1.6 GeV in the D₀₃ and P₀₁ partial waves of K⁺N scattering respectively, in agreement with experiments. We also find an indication of the J=3/2 Θ* spin-orbit partner to the Θ, in the P₀₃ partial wave at 1.6 GeV. We discuss the pros and cons of these findings in support of the interpretation of these peaks as possible exotics.

In this letter, the analytic relativistic bound state energy spectrum and wave functions of the s-wave Klein–Gordon equation for the generalized Hulthén potential are obtained through functional analytical method. The results also contain the analytic relativistic solutions of the s-wave Klein–Gordon equation for the Wood–Saxon and standard Hulthén potentials, however, the required results of the exponential potential are not derived from this paper.