In the previous videos of this series, we reviewed 12 out
of the 18 known elementary particles. These are six leptons and six quarks.
The remaining six elementary particles are five gauge bosons and Higgs Boson.
Bosons are sometimes called force particles, because it
is the bosons that control the interaction of physical
forces, such as electromagnetism and gravity.
The name of boson comes from the surname of Indian Physicist Satyendra Nath Bose,
a brilliant physicist who worked with Albert Einstein to
develop a method of analysis called Bose-Einstein statistics.
In the Standard Model, 3 out of the 4 fundamental forces
have a force-carrier particle i.e gauge boson, but there is
no force-carrier particle has been found for gravity.
Most physicists believe that leptons & quarks interact
by producing and absorbing gauge bosons.
The four gauge bosons are experimentally observed.
Let's start by examining these one by one.
The electromagnetic force is responsible for keeping a
magnet stuck to a metal. It also keeps electrons bound
in orbitals around the nucleus of an atom. So without
electromagnetic force, matter could not exist.
Photon is the electromagnetic force carrying boson and
known as the particle of light. The photon itself is a
massless, uncharged boson with spin 1. These are
stable and their own antiparticle.
Just as Photons, Gluons are the carriers or messengers of the
the strong nuclear force, which form & holds
protons & neutrons together with in nucleus of an atom.
As we know, there are two up quarks and one down
quark in a proton. Also two down quarks and one up
quark in neutron. These quarks are "glued" together by
particles called gluons.
A gluon has the ability to change the colour of a
quark in order to keep overall color
charge of the particle neutral i.e.
Red + Blue + Green = White
Like photons, gluons are massless, uncharged, spin 1
bosons. Furthermore, gluons possess color charge,
they can interact with other gluons.
Since gluons possess any one of three colours
and any of three anticolors, actually there are
nine combinations of gluons.
Antigluons are also gluons because reversing
all colours results in another gluon.
The Weak Nuclear Force is able to change one type of
particle into another at short distances.
It is responsible for phenomena such as the radioactive decay in unstable atoms.
The weak force is mediated by three different bosons.
the W+, W- and Z0. All three are spin 1 bosons and have mass.
Since W bosons, have electric charge (+1 or -1) . A weak
force interaction can change not only the type of
particle but also the charge + -1.
For example, a down quark can decay into an up quark
by emitting a W- or by absorbing W+.
Weak decays which involve Z0 boson, do not change the
charge of particle. The W+ is
the antiparticle of W- and vice -versa.
The Z0 is its own antiparticle.
In addition, there are other fundamental bosons predicted
but without clear experimental confirmation.
According to the Standard Model, the Higgs Boson is the
particle that gives rise to all masses.
On July 4, 2012, scientists at LHC announced that
they had good reason to believe, they'd found evidence
of the Higgs Boson.
Further research is ongoing to get better information
about the particle's exact properties. It is predicted
as a boson due to its quantum spin value of 0.
Second one is a Gravition. It is a theoretical particle
which has not been found experimentally.
As all other forces explained in terms of a gauge boson,
it is very natural to attempt the use of same mechanism
to explain gravity. Prediction of a quantum spin value of
graviton is 2.
Under the theory of supersymmetry, every fermion
would have a so-far-undetected bosonic counterpart.
Since there are 12 fundamental fermions, if
supersymmetry is true, there are another 12 fundamental
bosons that have not been detected yet.
Due to their high instability, they decayed into other forms.
