Modern Physics Letters A

We study lepton flavour-violating interactions which could result in the τ-lepton production in the ν_μN scattering or in μ → τ conversion on nucleons at high energies. Phenomenological bounds on the strength of interactions are extracted from the combined result of the NOMAD and CHORUS experiments on searching for ν_μ - ν_τ oscillations. Some of these bounds supersede limits from rare decays.

We also propose a "missing energy" type experiment searching for μ → τ conversion on nucleons. The experiment can be performed at a present accelerator or at a future neutrino factory.

Under the quenched approximation, we perform a lattice calculation for the mass of the ground 4⁺⁺ glueball state in E⁺⁺ channel on a D =3 + 1 lattice. Our calculation shows that the mass of this state is M_G (4⁺⁺) = 3.65(6)(18) GeV, which rules out the 4⁺⁺ or mainly 4⁺⁺ glueball state interpretation for ξ(2230).

Black hole entropy and its relation to the horizon area are considered. More precisely, the conditions and specifications that are expected to be required for the assignment of entropy, and the consequences that these expectations have when applied to a black hole are explored. In particular, the following questions are addressed: When do we expect to assign an entropy?; when are entropy and area proportional? and, what is the nature of the horizon? It is concluded that our present understanding of black hole entropy is somewhat incomplete, and some of the relevant issues that should be addressed in pursuing these questions are pointed out.

We argue that in four dimensions bosonic strings can be bundled together in a manner which resembles the way how individual filaments become bundled together to form a cable. The energy of such a bundle of strings is described by its extrinsic geometry, and it involves both torsion and curvature contributions. This leads to ordinary four-dimensional field theories, that describe the bundles of strings in terms of closed knotted solitons. Examples of field theories that can be constructed in this manner include the Faddeev model and the Skyrme model.

We investigate how the anticipated neutral current rate from SNO will sharpen our understanding of the solar neutrino anomaly. Quantitative analyses are performed with representative values of this rate in the expected range of 0.8–1.2. This would provide a 5–10σ signal for ν_e transition into a state containing an active neutrino component. Assuming this state to be purely active one can estimate both the ⁸B neutrino flux and the ν_e survival probability to a much higher precision than currently possible. Finally the measured value of the NC rate will have profound implications for the mass and mixing parameters of the solar neutrino oscillation solution.

The role of moduli stabilization in predictions for CP violation is examined in the context of four-dimensional effective supergravity models obtained from the weakly coupled heterotic string. We point out that while stabilization of compactification moduli has been studied extensively, the determination of background values for other scalars by dynamical means has not been subjected to the same degree of scrutiny. These other complex scalars are important potential sources of CP violation and we show in a simple model how their background values (including complex phases) may be determined from the minimization of the supergravity scalar potential, subject to the constraint of vanishing cosmological constant.

We comment on the recent claim for the experimental observation of neutrinoless double-beta decay. We discuss several limitations in the analysis provided in that paper and conclude that there is no basis for the presented claim.