25.6 Standard Model of Particle Physics Problem Set
25.1 The Big Idea
All matter is composed of fundamental building blocks, called the elementary particles. These building blocks are
much smaller than an atom, and so are sometimes referred to assubatomicparticles. Particles interact with one
another according to a set of laws. There are two types of particles: force particles (fermions) and matter particles
(bosons). What sets them apart is an intrinsic property called ’spin’. The set of particles and the laws that govern
their interactions are called the Standard Model. The Standard Model is very powerful and can predict particle
interactions to amazing accuracy.
The fifth of the five conservation laws is called CPT symmetry. CPT is a symmetry between matter and anti-matter.
The law states that if you reverse the spatial coordinates of a particle, change it from matter to anti-matter, and
reverse it in time the new object is now indistinguishable from the original. More on the fifth conservation law in
the Feynman Diagram’s chapter.