Modern Physics Letters A

The experimental ratios of the neutron to the proton densities at the nuclear periphery (≃ half-density radius + 2.5 fm) determined using very low energy anti-proton annihilation studies are compared with the predictions of the semi-phenomenological model of the nucleon density distributions. The model incorporates correctly two physical requirements: the correct asymptotic behavior (r → ∞) and the behavior near the center (r → 0).

The model gives a good account of the experiment. The results of the more sophisticated, microscopic mean field calculations like non-relativistic Hartree–Fock–Bogoliubov (HFB) with Skyrme type interactions though are qualitatively similar, the model density results are relatively closer to the experiment.

A spontaneously broken SU(2) × U(1) gauge theory with just one "primordial" generation of fermions is formulated in the context of generally covariant theory which contains two measures of integration in the action: the standard and a new Φd⁴x, where Φ is a density built out of degrees of freedom independent of the metric. Such type of models are known to produce a satisfactory answer to the cosmological constant problem. Global scale invariance is implemented. After SSB of scale invariance and gauge symmetry it is found that with the conditions appropriate to laboratory particle physics experiments, to each primordial fermion field corresponds three physical fermionic states. Two of them correspond to particles with different constant masses and they are identified with the first two generations of the electroweak theory. The third fermionic states at the classical level get nonpolynomial interactions which indicate the existence of fermionic condensate and fermionic mass generation.

We study the supersymmetric spontaneous symmetry breaking of SO(10) into SU(3) ⊗ SU(2) ⊗ U(1) for the most physically interesting cases of SU(5) or flipped SU(5) ⊗ U(1) intermediate symmetries. The first case is more easily realized while the second one requires a fine-tuning condition on the parameters of the superpotential. This is because in the case of SU(5) symmetry there is at most one singlet of the residual symmetry in each SO(10) irreducible representation. We also point out on more general grounds in supersymmetric GUTs that some intermediate symmetries can be exactly realized and others can only be approximated by fine-tuning. In the first category, there could occur some tunneling between the vacua with exact and approximate intermediate symmetry. The flipped SU(5) ⊗ U(1) symmetry improves the unification of gauge couplings if (B-L) is broken by ‖(B-L)‖ =1 scalars yielding right-handed neutrino masses below 10¹⁴GeV.

We consider three-point couplings in simple Lie algebras — singlets in triple tensor products of their integrable highest weight representations. A coupling can be expressed as a linear combination of products of finitely many elementary couplings. This carries over to affine fusion, the fusion of Wess–Zumino–Witten conformal field theories, where the expressions are in terms of elementary fusions. In the case of su(4) it has been observed that there is a purely affine elementary fusion, i.e. an elementary fusion that is not an elementary coupling. In this paper we show by construction that there is at least one purely affine elementary fusion associated to every su(N > 3).

The supersymmetric standard model of particle interactions is extended to include two Higgs triplet superfields at the TeV scale, carrying two units of lepton number. Realistic tree-level Majorana neutrino masses are obtained in the presence of soft, i.e. bilinear, R-parity nonconservation.

In this work, using a description of defects in solids in terms of three-dimensional gravity, we have obtained the changes on the spectrum energy and eigenfunctions of a bound particle, moving in a magnetic field, in a space with a linear topological defect, namely disclination and screw dislocation. We find exact expressions for the energy eigenvalue and eigenfunctions and compare these results with the ones obtained in the previous cases.

We consider the stabilization of de Sitter brane-world. The scalar field bulk-brane theory produces the nontrivial minimum of modulus potential where temporal radion is realized. The hierarchy problem (between Planck and electroweak scales) may be solved. However, the interpretation of radion is not so clear as in AdS brane-world. In particular, the introduction of two times physics or pair-creation of bulk spaces or identification of one of spatial coordinates with imaginary time (nonzero temperature) may be required.

In this paper we apply the averaging technique (using a right-invariant local gauge group measure) to local polynomials of the SU(N) gauge potential and show that the results are divergent and ill-defined.