After an historical introduction of the construction of the Standard Model, I will discuss why a scalar particle, called the Higgs boson, is needed.
The presence of an elementary scalar with a mass much smaller than the unification or the Planck scales generates, however, the hierarchy and fine tuning problems. To cure these problems one needs to extend the Standard Model. I will discuss two such extensions of the Standard Model: one based on supersymmetry where one introduces a supersymmetric partner for each particle of the Standard Model with a mass not much higher than 1 TeV and the other that assumes not an elementary, but rather a composite Higgs boson. This second possibility postulates the existence of a new interaction, called technicolour that is an extension of the colour symmetry needed for strong interactions.
Nordita is organizing a program on "Origin of mass 2012" from May 28th to
June 22nd where the new experimental results from the Large Hadron Collider (LHC) at Cern in Geneva will be discussed and compared with the theoretical predictions. This Nordita seminar will serve as an introduction to what will be discussed in the program.
