The non-Standard Model Higgs Boson(s)
Lecture notes
Part I (PDF - 3.5 MB)
Part II (PDF - 3.2 MB)
Part III (PDF - 3.5 MB)
Part IV (PDF - 2.8 MB)
Part V (PDF - 2.6 MB)
Abstract
1 Introduction and motivations
2 The current experimental information
2.1 The negative LEP searches
2.2 Indirect constraints from the precision tests
3 A heavier Higgs boson than expected?
3.1 A minimal example
4 Higgsless models
4.1 The ElectroWeak Chiral Lagrangian
4.2 A model in 5D
5 The Higgs boson from a larger symmetry
5.1 A strongly coupled SO(5) model
5.2 A perturbative minimal model
5.3 Non minimal models: little Higgs, holographic
6 The supersymmetric case
6.1 The MSSM Higgs sector reviewed
6.2 How heavy can the lightest scalar be?
6.3 Living below the LEP bound
6.4 A 5D model with susy broken by boundary conditions
7 Summary
About four decades from the formulation of the Standard Model (SM), more then three from the discovery of neutral currents and more then two from the finding of the weak bosons the Large Hadron Collider is about to make the first thorough experimental exploration of the energy scales at or well above the Fermi scale. This is the main motivation for this page, without forgetting the fact that the Higgs boson, as predicted by the SM at the heart of ElectroWeak Symmetry Breaking (EWSB), has not yet been found.
Much thought and many speculations have gone into the EWSB problem, impossible, and not even reasonable, to describe all. On the other hand, although my preference goes to it being related to supersymmetry, I find more useful, especially at this stage, to keep an open mind as to its possible manifestations/solutions: hence the partial choice of subjects that are described in the Downloads. The merits and the difficulties of the various possibilities should emerge from the relative discussions, with the last word left to the experiment, as in the normal way for physics to operate.
Riccardo Barbieri
Homepage
Scuola Normale Superiore
di Pisa, Italy