Neutrinoless double beta decay is a very important process both from the particle and nuclear physics point of view. From the elementary particle point of view it pops up in almost every model. In addition to the traditional mechanisms, like the light neutrino mass, λ and η terms etc we can have direct R-parity violating supersymmetric (SUSY) contributions. In any case its observation will seve...

Since particles such as molecules, atoms and nuclei are composite particles, it is important to recognize that physics must be invariant for the composite particles and their constituent particles, this requirement is called particle invariance in this paper. But difficulties arise immediately because for fermion we use the Dirac equation, for meson we use the Klein-Gordon equation and for clas...

Currently, a controversy is dividing physicists: Do the basic laws of nature operate only at the level of elementary particles (the reductionist position) or also (and differently) at higher levels of matter? If proponents of the former position are correct, then a complete explanation of physics can be achieved by studying the most basic particles in isolation. A similar controversy has long d...

An introduction to spin techniques in particle physics is given. Among the topics covered are: helicity formalism and its applications to the decay and scattering of spin-1/2 and spin-1 particles, techniques for evaluating helicity amplitudes (including projection operator methods and the spinor helicity method), and density matrix techniques. The utility of polarization and spin correlations f...

The purpose of this paper is to elucidate the concept of an elementary particle in the first-quantized Standard Model. The emphasis is upon the mathematical structures involved, rather than numerical computations. After the general concepts and philosophical outlook are introduced in the opening section, Section 2 addresses the question of what a free elementary particle is, paying particular a...

A central problem in the physics of elementary particles concerns the establishment of their quantum numbers. Recent developments in the theoretical classification of particles states have added impetus to this ac­ tivity as a means of making meaningful confrontation between theoretical proposals and experiment. In this review we confine our attention to the in­ ternal quantum numbers of spin a...

We consider gravitational scattering of point particles with Planckian centre-of-mass energy and fixed low momentum transfers in the framework of general relativity and dilaton gravity. The geometry around the particles are modelled by arbitrary black hole metrics of general relativity to calculate the scattering amplitudes. However, for dilaton gravity, this modelling can be done only by extre...

We discuss the possibility to observe the products of dark matter annihilation that was going on in the early Universe. Of all the particles that could be generated by this process we consider only photons, as they are both uncharged and easily detectable. The earlier the Universe was, the higher the dark matter concentration n and the annihilation rate (proportional to n) were. However, the em...

The old Weyl's idea of scale recalibration freedom and the Infeld's and van der Waerden's (IW) ideas concerning geometrical interpretation of the natural spinor phase gauge symmetry are discussed in the context of modern models of fundamental particle interactions. It is argued that IW gauge symmetry can be naturaly identified with U (1) symmetry of Weinberg-Salam model. It is also argued that ...