Modern Physics Letters A

By using symplectic Majorana spinors as Grassmann coordinates in a superspace associated with the supersymmetric extension of the isometry group on the spherical surface S₂, it proves possible to formulate supersymmetric models on S₂ using superspace techniques.

The two-photon two-neutrino interaction induced by magnetic field is investigated. In particular the processes and are studied in the presence of strong magnetic field. An effective Lagrangian and partial amplitudes of the processes are presented. Neutrino emissivities due to the reactions and are calculated taking into account the photon dispersion and large radiative corrections. A comparison of the results obtained with previous estimations and another inducing mechanisms of the processes under consideration is made.

We present the cosmological solution of the multi-brane/crystal universe model, to leading order in an expansion about the energy densities on branes, by using the generalized Goldberger–Wise mechanism to stabilize the extra dimension, and give general formula of the Friedmann equations. This is very interesting in the study of the cosmological phenomenon in the multi-brane/crystal universe model. We also compute the shift of the extra dimension between the adjacent branes.

The influence of hypersonic waves excited in a single crystal is investigated on the process of electron–positron pair creation by high-energy photons. The coherent part of the corresponding differential cross-section is derived as a function of the amplitude and wave number of the hypersound. The values of the parameters are specified for which the latter affects remarkably on the pair creation cross-section. It is shown that under certain conditions the presence of hypersonic waves can result in enhancement of the process cross-section.

We consider the Lagrangian path-integrals in Minkowski space for gauges with a residual gauge-invariance. From rather elementary considerations, we demonstrate the necessity of inclusion of an ε-term (even) in the formal treatments, without which one may reach incorrect conclusions. We show, further, that the ε-term can contribute to the BRST WT-identities in a nontrivial way (even as ε → 0). We also show that the (expectation value of the) correct ε-term satisfies an algebraic condition. We show by considering (a commonly used) example of a simple local quadratic ε-term, that lead to additional constraints on Green's function that are not normally taken into account in the BRST formalism which ignores the ε-term, and that they are characteristic of the way the singularities in propagators are handled. We argue that for a subclass of these gauges, the Minkowski path-integral could not be obtained by a Wick rotation from a Euclidean path-integral.

We examine the constraints from the recent HEIDELBERG–MOSCOW double beta decay experiment. It leads us to the almost degenerate or inverse hierarchy neutrino mass scenario. In this scenario, we obtain possible upper bounds for the Majorana CP violating phase in the lepton sector by incorporating the data from the neutrino oscillation, the single beta decay experiments, and from the astrophysical observation. We also predict the neutrino mass that may be measurable in the future beta decay experiments.