standard model of particle physics
model-e estânde-ye fizik-e zarre-yi
Fr.: modèle standard de la physique des particules
The theory developed since the 1970s, which is based on the theories and discoveries since the 1930s, and aims at explaining the fundamental structure of matter. According to the standard model, everything in the universe is made from a few basic building blocks called fundamental particles, governed by four fundamental forces. The particles occur in two basic types, called quarks and leptons. Three of the four fundamental forces (except gravity) and their carrier particles are included in the Standard Model. The Standard Model has successfully explained almost all experimental results and precisely predicted a wide variety of phenomena. Over time and through many experiments, the Standard Model has become established as a well-tested physics theory.
Fr.: particule étrange
An elementary particle created in high-energy particle collisions having a short life and a strangeness quantum number of 1. For example, sigma and xi baryons are strange particles. A strange particle is produced when a strange quark is created in a high-energy collision. → strangeness.
zarre-ye zir-atomi (#)
Fr.: particule subatomique
Any particle that is small compared to the size of the atom, e.g. an electron, proton, neutron, neutrino, quark, meson, all of which are either bosons or fermions.
In → plasma physics, → fluid dynamics, and → self-gravitating systems, a particle or ensemble of particles which are affected by the evolution of the rest of the system, but do not affect the rest of the system. The test particle concept is used, e.g., for revealing a flow, describing the path of fluid elements, and so on.
Fr.: particule virtuelle
A subatomic particle that, according to the uncertainty principle, comes into being out of energy fluctuations of the "vacuum" and lasts for extremely short periods of time. An electron-positron pair can exist only about 4 x 10-21 seconds. The lifetime increases as the mass and energy involved decreases. Virtual particles are real and have measurable effects, but cannot be directly observed, according to the uncertainty principle. → vacuum polarization.
Fr.: dualité onde-particule
The principle admitted in → quantum mechanics that
all particles have a wave-like nature and that waves have a particle aspect.
The wave-particle duality is of fundamental importance in obtaining a realistic picture of
the → elementary particles.