Modern Physics Letters A

The low-energy spectrum of a one-component, spontaneously broken Φ⁴ theory is generally believed to have the same simple massive form as in the symmetric phase where 〈Φ〉 = 0. However, in lattice simulations of the 4D Ising limit of the theory, the two-point connected correlator and the connected scalar propagator show deviations from a standard massive behavior that do not exist in the symmetric phase. As a support for this observed discrepancy, we present a variational, analytic calculation of the energy spectrum E₁(p) in the broken phase. This analytic result, while providing the trend at large |p|, gives an energy gap E₁(0)< m_h, even when approaching the infinite-cutoff limit Λ→∞ with that infinitesimal coupling λ ~ 1/ln Λ suggested by the standard interpretation of "triviality" within leading-order perturbation theory. We also compare with other approaches and discuss the more general implications of the result.

We have shown that the possibility of the existence of the mixed phase of the non-uniform chiral (NCh) and the color superconducting (2SC) ground state depends significantly on the choice of the parameters and type of the regularization scheme. Our calculations indicate that irrespective of the choice of regularization type, in a moderate baryon density region, there is a local minimum of a system corresponding to the NCh/2SC related phase. In the 3d cutoff regularization scheme, the mixed region of the NCh and the 2SC phases exists for a broad set of NJL model parameters. However, in the Schwinger regularization scheme, if parameters are set to the vacuum values of f_π, m_π and , then the mixed region of the NCh and the 2SC phases does not exist.

An unified approximated solution for symmetric Skyrmions was proposed for the SU(2) Skyrme model for baryon numbers up to 8, which take the hybrid form of a kink-like solution and that given by the instanton method. The Skyrmion profiles are examined by computing lowest soliton energy as well as the static properties of nucleons within the framework of collective quantization, with a good agreement with the exact numerical results. The comparisons with the previous computations as well as the experimental data are also presented.

We construct a neutrino mass matrix M_ν via a seesaw mechanism with perturbed invariant under a cyclic permutation by introducing a parameter δ into the diagonal elements of M_ν with the assumption that trace of the perturbed M_ν is equal to trace of the unperturbed M_ν. We found that the perturbed neutrino mass matrices M_ν can predict the mass-squared difference with the possible hierarchy of neutrino mass is normal or inverted hierarchy. By using the advantages of the mass-squared differences and mixing parameters data from neutrino oscillation experiments, we then have neutrino masses in inverted hierarchy with masses: |m₁| = 0.101023 eV, |m₂| = 0.101428 eV and |m₃| = 0.084413 eV.

We study a compact star comprising strange matter content in the presence of pressure anisotropy. Considering strange matter with equation of state p = (ρ-4B)/3, where B is Bag parameter, we analyze the effect of pressure anisotropy on the Bag parameter for a compact star described by Vaidya–Tikekar metric. The values of B inside and on surface of the star are determined for different anisotropy parameter α. It is found that in the vicinity of the center of a compact star, B parameter is almost constant. However, away from the center B varies with the radial distance and finally at the surface B attains a value independent of the anisotropy. It is also noted that for some values of α, B remains constant throughout the star. Given α and spheriodicity a, B is found to be decreasing with the increase in compactness factor. The models admitting B increasing with α for a given spheriodicity parameter (a) and compactness are also found.

The dynamics of a (charged) pseudo-classical spinning particle, that evolves on a curved space, are addressed. Besides the Dirac approach, we give a consistent Hamiltonian analysis of the spinning particle without using the Dirac bracket. The link between our treatment and Dirac formalism is evidenced.