الفهرس 
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Abstract
Particle physics is the branch in which the elementary subatomic constituents of matter
(fields) and their interactions (forces) are studied. This branch is also called high energy
physics, because many elementary particles can only be created artificially during high energy
collisions with other particles in particle accelerators [1).
In the standard model only twelve particles of spin Yi known as fermions with corresponding
antiparticles, that made all forms of matter, interacting through fields of which they are the
sources and they are listed in table 1.1. These twelve particles are distinctly divided into two
groups called the quarks and the leptons. The six leptons and the six quarks are grouped in pairs
to form generations where the corresponding particles in each generation exhibit similar
physical behavior. Each particle of a generation has greater mass than that of the corresponding
particle of lower generation. The charged particles of all generations are thought to be
fundamental and there are no pieces within them, also neutrinos of all generations do not decay
and pervade the universe, but they are influenced only by weak nuclear forces.
The standard model also recognizes four forces to be fundamental forces, the gravity, the
electroweak force and the strong force.’ These four forces result from matter particles
exchanging other particles known as force mediating particles and the mediating particles are
called the gauge bosons. The matter fields can interact with each other through different kinds
of fields called gauge fields. These fields also have their own excitations.