Introduction

People loves symmetry! Nature seems to love symmetry, or better, our model of Nature loves symmetry. When a picture frame is not vertical, all (or almost all) of us feel a compulsion that forces us to exert a force just to restore the axial symmetry that was previously broken. In the same way, Nature (or our model of It) makes to appear forces, the fundamental forces, to restore a Fundamental Symmetry: Gauge Symmetry.

The main subject of these lectures is precisely Symmetry as the basis of forces and the main goal should be to make you to ``love" the symmetry based Theory of the Fundamental Interactions.

As in a play, let's begin by the beginning with the introduction of the characters. We will easily remember their names reading the following table:

$$\left[ \begin{array}{rlll} \nu_{e}\;\mid\; & u_{1} & u_{2} ... ...\\ \tau\;\mid\; & b_{1} & b_{2} & b_{3} \end{array} \right]$$

Fermion Generations or Families

$$gluons g_{1}, g_{2}, \dots, g_{8}$$

$$photon \gamma$$

$$\lq\lq weakons'' W^{+}, W^{-}, Z$$

$$\lq\lq graviton'' G$$

Intermediate Bosons

$$H$$

Higgs Boson

It is worth noticing that these are the characters of our present level of elementarity and that is why they bear today the name of ``elementary (?) particles (?)".

Figure 1: Fundamental Interactions

Again, as in a play we watch the interactions of the characters. We will try to remember the features of these forces of the nature through the diagram of the relative intensities of the interactions versus their respective range shown in Figure 1. The mediators of the forces with their respective masses proportional to their range are also shown.