Neutrino masses from nonstandard supersymmetry breaking terms

Naturally small Majorana neutrino masses arise from nonstandard supersymmetry breaking terms. This mechanism works in the minimal supersymmetric framework and does not require extra particles or new mass scales. It could also be responsible for proton decay even in the absence of Grand Unification.Comment: 7 pages, 3 eps figures; important note on baryon number violation added; small editorial changes mad

On intersection of domain walls in a supersymmetric model

We consider a classical field configuration, corresponding to intersection of two domain walls in a supersymmetric model, where the field profile for two parallel walls at a finite separation is known explicitly. An approximation to the solution for intersecting walls is constructed for a small angle at the intersection. We find a finite effective length of the intersection region and also an energy, associated with the intersection.Comment: 12 pages, LaTeX, 4 figures, ep

What Becomes of Vortices in Theories with Flat Directions

In many theories with flat directions of scalar potential, static vortex solutions do not exist for a generic choice of vacuum. In two Euclidean dimensions, we find their substitutes --- constrained instantons consisting of compact core formed by Abrikosov--Nielsen--Olesen vortex and long-ranged cloud of modulus field. In (3+1) dimensions, an initial compact configuration of string topology evolves in such a way that at every point in space the modulus relaxes, in a universal manner, to one and the same value characteristic to the theory.Comment: 8 pages, latex, 3 figures, uses axodraw.st

Zeros of tree amplitudes at rest and symmetries of mechanical systems

We consider the tree amplitudes of production of $n_2$ scalar particles by $n_1$ particles of another kind, where both initial and final particles are at rest and on mass shell, in a model of two scalar fields with $O(2)$ symmetric interaction and unequal masses. We find that these amplitudes are zero except for the lowest possible $n_1$ and $n_2$, and that the cancellation of the corresponding Feynman graphs occurs due to a special symmetry of the classical mechanical counterpart of this theory. This feature is rather general and is inherent in various other scalar field theories.Comment: 11 pages Preprint INR-830/93, August 199

Three generations on a local vortex in extra dimensions

We develop an approach to the origin of three generations of the Standard Model fermions from one generation in a higher-dimensional theory, where four-dimensional fermions appear as zero modes trapped in the core of a topological defect, and the hierarchy of masses and mixings is produced by wave function overlaps in extra dimensions. We present a model with unbroken U(1) symmetry where three zero modes appear on an Abrikosov-Nielsen-Olesen vortex due to nontrivial scalar--fermion interactions.Comment: 8 pages, no figure

Tree amplitudes at multiparticle threshold in a model with softly broken O(2)O(2) symmetry

Tree amplitudes of the production of two kinds of scalar particles at threshold from one virtual particle are calculated in a model of two scalar fields with $O(2)$ symmetric quartic interaction and unequal masses. These amplitudes exhibit interesting factorial and exponential behaviour at large multiplicities. As a by-product we observe that the kinematically allowed decay of one real particle into $n$ real particles of another kind, all at rest, has zero tree amplitude in this model for $n>2$.Comment: 17 pages. Preprint INR-823/9

Dynamical supersymmetry breaking and unification of couplings

We consider the possibility of unification of the Supersymmetric Standard Model gauge groups with those of the dynamical supersymmetry breaking (DSB) sector in theories with gauge mediated supersymmetry breaking. We find constraints on the DSB gauge group beta function that come from unification of the gauge coupling constants of the two sectors. These constraints are satisfied by a fairly wide class of models. We discuss possible unification scenarios in the context of a simple model.Comment: 7 pages, LaTeX; grant numbers correcte

Constraining holographic technicolor

We obtain a new bound on the value of Peskin-Takeuchi S parameter in a wide class of bottom-up holographic models for technicolor. Namely, we show that weakly coupled holographic description in these models implies S>>0.2. Our bound is in conflict with the results of electroweak precision measurements, so it strongly disfavors the models we consider.Comment: 8 pages; journal versio

Magnetic deflections and possible sources of the ultra-high-energy cosmic rays in the AGASA-HiRes-Yakutsk cluster

The cluster of ultra-high-energy cosmic rays observed by the AGASA, HiRes and Yakutsk experiments is studied with respect to possible deflections of particles in regular magnetic fields. Best-fit positions of a potential source of these clustered particles are found, with account of the errors in energy estimation, both in the frameworks of particular models of the Galactic magnetic field and treating the direction and the amount of deflection as free parameters. The study suggests that an unknown regular component of either Galactic or extragalactic magnetic field may dominate over modelled components in the direction of the cluster. Possible sources of the cosmic rays in that direction are considered.Comment: 18 pages, 3 eps figures, iopart.cl

BPS Domain Wall Junctions in Infinitely Large Extra Dimensions

We consider models of scalar fields coupled to gravity which are higher-dimensional generalizations of four dimensional supergravity. We use these models to describe domain wall junctions in an anti-de Sitter background. We derive Bogomolnyi equations for the scalar fields from which the walls are constructed and for the metric. From these equations a BPS-like formula for the junction energy can be derived. We demonstrate that such junctions localize gravity in the presence of more than one uncompactified extra dimension.Comment: 17 pages, uses RevTeX, new references adde