Modern Physics Letters A

We present a brief summary of the developments of no-boundary quantum cosmology for the last three decades.

In induced fusion–fission reaction, resultant compound system loses a part of its energy via γ-ray emission both before and after scission point that can be measured using proper apparatus. A dynamical Monte Carlo simulation based on the multi-dimensional Langevin equations (L.E) has been applied to obtain γ-ray multiplicity emitted from highly excited compound nucleus. In this study, γ-ray multiplicity has been calculated following the ¹⁹F+²³²Th, ¹²C+²³²Th and ¹⁶O+²³²Th reactions. Comparison of calculated results for symmetry and asymmetry fission show γ-ray multiplicity in symmetry fission is higher than asymmetry fission especially in higher energies.

We study the analogue of the Aharonov–Bohm effect for bound states for a neutral particle with a permanent magnetic dipole moment interacting with an external field. We consider a neutral particle confined to moving between two coaxial cylinders and show the dependence of the energy levels on the Aharonov-Casher quantum flux. Moreover, we show that the same flux dependence of the bound states can be found when the neutral particle is confined to a one-dimensional quantum ring and a quantum dot, and we also calculate the persistent currents in each case.

The problem of finding a systematic computation of the gauge-invariant extension of WZW term by using equivariant cohomology is addressed. Witten's analysis for the two-dimensional case is extended to higher dimensions, in particular to four dimensions. It is shown that Cartan's model is used to find the anomaly cancellation condition while Weil's model is more appropriated to express the gauge-invariant extension of the WZW term. In the process we point out that both models are also useful to emphasize some nice relations with the Abelian anomaly.

Most attractive channel is studied for SU(5) grand unified theory in five dimensions where 5* and 10 fermions and a 24 gauge boson propagate in the bulk. If there are bulk fermions with zero mode for the chirality opposite to quark and lepton multiplets, they can contribute to forming 5, 24, 50 and 75 scalar bound states. We find that the inclusion of a simple anomaly-free set for zero mode yields scalar bound states whose binding strengths are the largest for 24 and the second largest for 5. This corresponds to the breaking pattern of the SU(5) to color and electromagnetism via the standard model gauge group.

We have studied the topological expression of the reduced quantum trajectory using ϕ-mapping topological current theory and reduced density matrix theory. Moreover, we have proposed a new topological expression called the reduced quantum topological trajectory. Ignoring the coefficients of the winding number, we have found that the expression for the reduced quantum topological trajectory is the same for coherence as it is for decoherence. Under certain conditions, the vorticity of the reduced quantum topological trajectory is a topological invariant.

A triangular ansatz for the seesaw mechanism and baryogenesis via leptogenesis is explored. In a basis where both the charged lepton and the Majorana mass matrix are diagonal, the Dirac mass matrix can generally be written as the product of a unitary times a triangular matrix. We assume the unitary matrix to be the identity and then an upper triangular Dirac matrix. Constraints from bilarge lepton mixing and leptogenesis are studied.