Particle zoo
Encyclopedia
In particle physics
, the term particle zoo is used colloquially to describe a relatively extensive list of the known elementary particles that almost look like hundreds of species in the zoo.
The situation was particularly confusing in the late 1960s, before the discovery of quarks, when hundreds of strongly interacting particles (hadron
s) were known. It turned out later that they were not elementary but rather composites of the quark
s. The set of particles believed today to be elementary is known as the Standard Model
.
According to string theory
, all particles in the "zoo" have a common ancestor, namely a vibrating string.
Particle physics
Particle physics is a branch of physics that studies the existence and interactions of particles that are the constituents of what is usually referred to as matter or radiation. In current understanding, particles are excitations of quantum fields and interact following their dynamics...
, the term particle zoo is used colloquially to describe a relatively extensive list of the known elementary particles that almost look like hundreds of species in the zoo.
The situation was particularly confusing in the late 1960s, before the discovery of quarks, when hundreds of strongly interacting particles (hadron
Hadron
In particle physics, a hadron is a composite particle made of quarks held together by the strong force...
s) were known. It turned out later that they were not elementary but rather composites of the quark
Quark
A quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly...
s. The set of particles believed today to be elementary is known as the Standard Model
Standard Model
The Standard Model of particle physics is a theory concerning the electromagnetic, weak, and strong nuclear interactions, which mediate the dynamics of the known subatomic particles. Developed throughout the mid to late 20th century, the current formulation was finalized in the mid 1970s upon...
.
According to string theory
String theory
String theory is an active research framework in particle physics that attempts to reconcile quantum mechanics and general relativity. It is a contender for a theory of everything , a manner of describing the known fundamental forces and matter in a mathematically complete system...
, all particles in the "zoo" have a common ancestor, namely a vibrating string.