International Journal of Modern Physics E

Primordial nucleosynthesis provides a probe of the Universe during its early evolution. Given the progress exploring the constituents, structure, and recent evolution of the Universe, it is timely to review the status of Big Bang Nucleosynthesis (BBN) and to confront its predictions, and the constraints which emerge from them, with those derived from independent observations of the Universe at much later epochs in its evolution. Following an overview of the key physics controlling element synthesis in the early Universe, the predictions of the standard models of cosmology and particle physics (SBBN) are presented, along with those from some non-standard models. The observational data used to infer the primordial abundances are described, with an emphasis on the distinction between precision and accuracy. These relic abundances are compared with predictions, testing the internal consistency of BBN and enabling a comparison of the BBN constraints with those derived from the WMAP Cosmic Background Radiation data. Emerging from these comparisons is a successful standard model along with constraints on (or hints of) physics beyond the standard models of particle physics and of cosmology.

The historical context of the recent results from high energy heavy ion reactions devoted to the search of quark-gluon plasma (QGP) is reviewed, with emphasis on the surprises encountered. The evidence for QGP from heavy ion reactions is compared with that available from particle reactions.

The relativistic five-quark equations are found in the framework of the dispersion relation technique. The five-quark amplitudes for the low-lying pentaquarks including u, d quarks are calculated. The poles of the five-quark amplitudes determine the masses of the ududţ and uuuuţ pentaquarks. The calculated of pentaquark amplitudes estimates the contributions of four subamplitudes. The main contributions to the pentaquark amplitude are determined by the subamplitudes, which include the meson states M.

The relativistic five-quark equations are found in the framework of the dispersion relation technique. The five-quark amplitudes for the low-lying pentaquarks including the u, d, s-quarks are calculated. The poles of these amplitudes determine the masses of the nucleon and the Ξ^–– pentaquarks. The mass spectra of the lowest pentaquarks with the are calculated. The mass values of the positive and negative parity pentaquarks are determined by the mixing of both 0⁺ and 1⁺ diquarks.

The pseudo-spin concept and the SD-pair shell model provide for tractable truncations of large model spaces. We tested the compatibility of these concepts, and hence the applicability of the SD-pair shell model to its pseudo SD-pair analog, for the (1h_9/2 2f_7/2 2f_5/2 3p_3/2 3p_1/2)⁸ system. The validity of the SD-pair concept is found to survive under pseudo-spin transformation.

We study high energy proton-proton (pp) elastic reactions in a meson-exchange model. The observed differential cross sections at small momentum exchanges (|t|<0.8 GeV²) are well reproduced for a large energy range (s~100 to 1000 GeV²) in the model. Our study reveals that the meson-exchange model developed in the low and medium energy sector is applicable to the high-energy pp elastic reactions. It might be argued that high-energy reactions at small momentum transfers might be as soft as low and medium energy processes.

The mass differences of the flavor octet and decuplet ground-state baryons are studied in the perturbative chiral quark model. We present a way to understand the nontrivial spin- and flavor-dependent mass differences, whereby both pseudoscalar mesons and gluons play a significant role.

The Gell-Mann and Levy model, as well as the Birse and Banerjee model, describe quark interactions via the exchange of σ- and π-mesons. We extend these models to include higher order mesonic interactions. The field equations were solved in the mean-field approximation and good agreement with the data for nucleon properties was obtained. Our agreement is better than that obtained by the original model of Birse and Banerjee and by other models. This indicates the importance of including higher order meson correlations.

Advances achieved during recent years in model and ab initio descriptions of fission of metal clusters are reviewed. We focus on developments in ab initio treatment of the electronic subsystem within the jellium background model, as well as on applications of potential energy surface analysis to determining the characteristics of the fission process. We reiterate the main results obtained with the implementation of the Hartree–Fock and local density schemes for the two-center deformed jellium model. We overview the influences of the geometrical and statistical factors on the parameters of the fission process revealed recently. Also, we overview concisely the classical liquid drop model, the shell correction method, the asymmetric two-center-oscillator shell model, and the main approaches to the molecular dynamics simulations of the fission process.

Identical boson Hanbury-Brown–Twiss interferometry as applied to relativistic heavy-ion collisions is reviewed. Emphasis is placed on the use of hadronic scattering models to interpret the physical significance of experimental results. Interferometric studies with center-of-mass energies from <1 GeV/nucleon up to 5500 GeV/nucleon are considered.

We measured the excitation functions for nine evaporation residues for the ¹²C + ¹¹⁵In system in the energy range well beyond the Coulomb barrier. The experimental results are compared with the theoretical values calculated using the Monte Carlo simulation code PACE2. Several complete and incomplete fusion products are observed in the present study. It is observed that a definite amount of incomplete fusion contribution is present, even at the lowest energy. The results clearly show the incomplete fusion contributions in the iodine and antimony products.

The hyper-spherical adiabatic expansion is a representation for the investigation of the muonic three-body bound states. In this research, we have used the method of hyper-spherical "surface" functions for the muonic molecule, tritium-tritium-muon. Through this approach, the binding energy of the ground state and the lowest eigenpotentials for the muonic molecular ions are calculated in the extreme adiabatic approximation. The results obtained are close to the calculation of other researchers.

It is taken for granted in modern high energy approaches, that the Planck scale is the minimum scale. We investigate why this should be so, and provide a rationale for its numerical value.

Positive baryon numbers (A>0) and positive lepton numbers (L>0) characterize matter particles while negative baryon numbers and negative lepton numbers characterize antimatter particles. Matter particles and antimatter particles belong to two distinct classes of particles. Matter neutral particles are particles characterized by both zero baryon number and zero lepton number. This third class of particles includes mesons formed by a quark and an antiquark pair (a pair of matter particle and antimatter particle) and bosons which are messengers of known interactions (photons for electromagnetism, W and Z bosons for the weak interaction, gluons for the strong interaction). The antiparticle of a matter particle belongs to the class of antimatter particles, the antiparticle of an antimatter particle belongs to the class of matter particles. The antiparticle of a matter neutral particle belongs to the same class of matter neutral particles. A truly neutral particle is a particle identical with its antiparticle; it belongs necessarily to the class of matter neutral particles. All known interactions of the Standard Model conserve baryon number and lepton number; matter cannot be created or destroyed via a reaction governed by these interactions. Conservation of baryon and lepton number parallels conservation of atoms in chemistry; the number of atoms of a particular species in the reactants must equal the number of those atoms in the products. These laws of conservation valid for interaction involving matter particles are indeed valid for any particles (matter particles characterized by positive numbers, antimatter particles characterized by negative numbers, and matter neutral particles characterized by zero). Interactions within the framework of the Standard Model which conserve both matter and charge at the microscopic level cannot explain the observed asymmetry of our Universe. The strong interaction was introduced to explain the stability of nuclei: there must exist a powerful force to compensate the electromagnetic force which tends to cause protons to fly apart. The weak interaction with laws of conservation different from electromagnetism and the strong interaction was postulated to explain beta decay. Our observed material and neutral universe would signify the existence of another interaction that did conserve charge but did not conserve matter.