standard model

The Standard Model

If we recapitulate?

Now that we have done the tour of all the elementary particles of matter (fermions) and of vector particles (bosons) the 4 fundamental forces of the Universe, we are ready to bring it all together. This synthesis of current knowledge, without doubt provisional, is called the standard model.
This model rests on quantum physics and relativity and benefits from a very large consensus in the community of particle physicists. It uses a very elaborate mathematical formulation which is also very hermetic for the non-specialist. The power of this formulation comes from that which it has permitted to be predicted such as the existance of particles (for example intermediary bosons) which have subsequently been discovered experimentally. Electrodynamics and quantum chromodynamics form part of this model and permit the explanation of all of the interactions except gravitation (the graviton has never been detected).

This model then allows us to explain all of the observable phenomena at the scale of particles.
We can summarise this with two tables:

**FERMIONS: particles of matter Spin = 1/2...**
QUARKS Q = 2/3	up quark u	charm quark c	top quark t
QUARKS Q = -1/3	down quark d	strange quark s	bottom quark b
LEPTONS Q = -1	electron e^-	muon m^-	tau t^-
LEPTONS Q = 0	electronic neutrino n_e	muonic neutrino n_m	tau neutrino n_t

Other FERMION table

We have then 12 elementary particles to which we need to add the 12 corresponding antiparticles = 24 elementary particles .

**BOSONS: interaction mediator particles Spin = 1...**
Boson	interaction	range	intensity	actors	charge sensible
graviton ?	gravitational	infinite	10 ^-38	all particles	mass, energy
photon	electro- magnetic	infinite	10^-2	all fermions except neutrinos	electric Q charge
8 gluons	strong	10 ^-15 m.	1	all quarks	colour charge
3 bosons: W⁺ W^- Z⁰	weak	10^-18 m.	10^-7	all fermions	weak charge

Other BOSON table

We have 13 bosons to which we need to add the corresponding antibosons.
Recall that the photon is its own antiparticle and that the graviton remains hypothetical.

N.B.:To this last table grouping together all of the boson, it is convenient to add one: the Higgs boson which is also the most mysterious of all. We have spoken of this in the chapter dealing with Grand Unification!

The standard model then finally describes around fifty truly elementary particles.

Without doubt it will not be the ultimate theory of matter: it is nothing but a current synthesis of our knowledge about matter.

The great dream of physicists is to simplify this model:

in unifying the 4 forces into a single superforce: this is the Superforce theory. Already electromagnetism and the weak interaction have been unified in the weakelectro force.
in unifying all of the elementary particles into a single one: this is the supercords theory