ﻻ يوجد ملخص باللغة العربية
Taking a two interacting scalar toy model with interaction term $gphichi^2$, we study the production of $chi$-particles coming from the decay of an asymptotic and highly occupied beam of $phi$-particles. We perform a non-perturbative analysis coming from parametric resonant instabilities and investigate the possibility that massive $chi$-particles are produced from decays of massless $phi$-particles from the beam. Although this process is not present in a perturbative analysis, our non perturbative approach allows it to happen under certain conditions. For a momentum $p$ of the beam particles and a mass $m_chi$ of the produced ones, we find that the decay is allowed if the energy density of the beam exceeds the instability threshold $p^2mc^4/(2g^2)$. We also provide an analytical expression for the spontaneous decay rate at the earliest time.
We give the exact solution of classical equation of motion of a quartic scalar massless field theory showing that this is massive and is represented by a superposition of free particle solutions with a discrete spectrum. Then we show that this is als
Electromagnetic fields of a massless charged particle are described by a gauge potential that is almost everywhere pure gauge. Solution of quantum mechanical wave equations in the presence of such fields is therefore immediate and leads to a new deri
Thermodynamic properties of a system of interacting bosonic particles and antiparticles at finite temperatures are studied within the framework of a thermodynamically consistent mean field model. The mean field contains both attractive and repulsive
It is important to obtain (nearly) massless localized modes for the low-energy four-dimensional effective field theory in the brane-world scenario. We propose a mechanism for bosonic zero modes using the field-dependent kinetic function in the classi
By using a Hamiltonian based on the coupling through flux lines, we have calculated the interaction energy between two fermions via massless bosons as well as via massive particles. In the case of interaction via massless bosons we obtain an equivale