Modern Physics Letters A

Signatures of anomaly mediated supersymmetry breaking in linear colliders are briefly reviewed after presenting an outline of the theoretical framework. A unique and distinct feature of a large class of models of this type is a winolike chargino which is very closely degenerate in mass with the lightest neutralino. The very slow decay of this chargino results in a heavily ionizing charged track and one soft charged pion with a characteristic momentum distribution, leading to unique signals in linear colliders which are essentially free of background. The determination of chargino and slepton masses from such events is a distinctly interesting possibility.

We investigate the coherent bremsstrahlung by relativistic electrons in a single crystal excited by hypersonic vibrations. The formula for the corresponding differential cross-section is derived in the case of a sinusoidal wave. The conditions are specified under which the influence of the hypersound is essential. The case is considered in detail when the electron enters into the crystal at small angles with respect to a crystallographic axis. It is shown that in dependence of the parameters, the presence of hypersonic waves can either enhance or reduce the bremsstrahlung cross-section.

We re-evaluate the zero point Casimir energy for the case of a massive scalar field in R¹×S³ space, allowing also for deviations from the standard conformal value ξ=1/6, by means of zero temperature zeta function techniques. We show that for the problem at hand this approach is equivalent to the high temperature regularization of the vacuum energy, as conjectured in a previous publication. The analytic continuation can be performed in two ways, which are seen to be equivalent.

The early cosmic inflation, when taken along with the recent observations that the universe is currently dominated by a low density vacuum energy, leads to at least two potential problems which modern cosmology must address. First, there is the old cosmological constant problem, with a new twist: the coincidence problem. Secondly, cosmology still lacks a model to predict the observed current cosmic acceleration and to determine whether or not there is a future exit out of this state (as previously in the inflationary case). This constitutes (what is called here) a dynamical problem. Here a framework is proposed to address these two problems, based on treating the cosmic background vacuum (dark) energy as both dynamical and interacting. The universe behaves as a vacuum-driven cosmic engine which, in search of equilibrium, always back-reacts to vacuum-induced accelerations by increasing its inertia (internal energy) through vacuum energy dissipation. The process couples cosmic vacuum (dark) energy to matter to produce future-directed increasingly comparable amplitudes in these fields by setting up oscillations in the decaying vacuum energy density and corresponding sympathetic ones in the matter fields. By putting bounds on the relative magnitudes of these coupled oscillations the model offers a natural and conceptually simple channel to discuss the coincidence problem, while also suggesting a way to deal with the dynamical problem. A result with important observational implications is an equation of state w(t) which specifically predicts a variable, quasi-periodic, acceleration for the current universe. This result can be directly tested by future observational techniques such as SNAP.

We obtain in analytical form the dressed propagator of the massive Rarita–Schwinger field taking into account all spin components and discuss shortly its properties.

We use exact results in a new approach to quantum gravity to study the effect of quantum loop corrections on the behavior of the metric of spacetime near the Schwarzschild radius of a massive point particle in the standard model. We show that the classical conclusion that such a system is a black hole is obviated. Phenomenological implications are discussed.

Two-dimensional gravity with torsion is investigated using the Hamilton–Jacobi formalism. The equations of motion and the action integral are obtained as total differential equations in many variables. The integrabilty conditions, lead us to obtain the path integral quantization as an integration over the canonical phase-space coordinates.

If the unitary quark-mixing matrix, V, is moduli symmetric, it will depend on three real parameters. This means that there is a relation between the four parameters needed to parametrize a general V. It is shown that there exists a very simple relation involving |V₁₁|², |V₃₃|², and . This relation is compared with the present experimental data. It is concluded that a moduli symmetric V is not ruled out.