Download The Standard Model (SM) describes the fundamental particles of the

The Standard Model (SM) describes the fundamental particles of the universe
and the ways in which they interact. The SM describes 36 fundamental
particles and three types of fundamental interactions.
Fermions –
All fermions have half-integer spin (intrinsic angular momentum). As a result of their spin, all fermions obey the Pauli Exclusion Principle
which asserts that no two particles can exist in the same state at the same time. Fermions in the SM are subdivided into leptons and quarks,
which are commonly referred to as matter particles.
Quarks – These are particles that are never found on their own and have fractional electric charges. Quarks come in six flavors: up, down,
top, bottom, charm, and strange. Each quark has an associated anti-quark, typically indicated with a bar over the symbol. Quarks form two
types of composite particles, baryons and mesons. Baryons are made up of three quarks and mesons are made of a quark and an anti-quark.
The proton is an example of a baryon.
Leptons – These are particles with integer electric charge values and can be found alone. The six leptons are: the electron, muon, tau,
electron neutrino, muon neutrino, and tau neutrino. Like quarks, each lepton has an associated anti-particle.
Bosons –
All bosons have integer spin. Bosons in the SM are usually force carrier particles, referred to as gauge bosons. The only boson that does
not act as a mediating particle for one of the three fundamental forces of the SM is the Higgs boson. The Higgs boson is theoretically
responsible for giving mass to other particles through interactions with the Higgs field. Yet to be discovered, the Higgs boson is a major
focus of research at the Tevatron at Fermilab in Batavia, Illinois, and the Large Hadron Collider at CERN in Geneva, Switzerland. The W + , Wand Z bosons mediate the weak force, the photon mediates the electromagnetic force, and gluons mediate the strong force.
Fundamental Interactions –
Electromagnetic (EM) – This interaction deals with electrically charged particles. Any particle with electric charge creates an electric field,
and if the charge is moving it creates a magnetic field. This interaction is mediated by the exchange of the photon, a boson having no mass
or charge. An electron held in orbit by the positive nucleus of an atom is an example of the EM force at work.
Weak – This interaction is responsible for flavor change. That is, the weak force explains why heavy and unstable quarks and leptons are
able to decay. A common example of this is beta decay. The weak force is responsible for the nuclear fusion process that is the source of the
Sun's energy. The weak force is mediated by the exchange of the massive gauge bosons, W+/- and Z. The electromagnetic and weak force are
recognized to be different manifestations of only one force, the electroweak force.
Strong – This interaction is so named because it is the strongest of the fundamental forces. It is mediated by gluons, which are responsible
for holding together quarks in protons and neutrons, the constituents of atomic nuclei. The strong interaction creates a binding force
stronger than the electromagnetic repulsion between the positive protons in the nucleus.
Physics and Arts Exhibition at UB
August 2009