LHC physics
The Large Hadron
Collider, LHC, is a proton-proton collider designed to operate at a
center-of-mass energy of 14 TeV and a luminosity of 1034
cm-2s-1. It will start operating in 2007 at the
European Particle Physics Research Center CERN in Geneva, Switzerland.
The high energy and luminosity of LHC offers a large range of physics
opportunities from the precise measurement of the properties of known
objects such as the top quark and B mesons to the exploration of the
high energy frontier. While the present Standard Model of particle
physics provides a very successful description of the interactions of
the components of matter at presently available energies (200 GeV), new
physics is bound to appear in the 1 TeV energy scale.
In the context of the Standard Model, the electroweak symmetry breaking is expected to occur via the Higgs mechanism, producing one or several Higgs bosons, observable below about 1 TeV. The Standard Model, however, is theoretically not a satisfactory theory beyond the electroweak mass scale. Among the models beyond the Standard Model, supersymmetry is presently the most favoured one. Supersymmetry provides an elegant cancellation of divergences arising from radiative corrections. Furthermore, supersymmetry is a necessary ingredient in the only presently known mechanism for incorporating gravity into a quantum theory of particle interactions. Supersymmetric models postulate the existence of supersymmetric partners for all elementary particles; therefore, the model predicts clear physical signatures in form of observable new particles. In other scenarios such as ‘technicolor’, the electroweak symmetry is broken dynamically; again, new particles are bound to appear.
Finally, there are also other possibilities for new physics that are not directly related to electroweak symmetry breaking: there could be new quarks, charged leptons or massive neutrinos, new symmetries with associated gauge bosons, or elementary particles could turn out to be composite objects. Recently, extra dimensions at the TeV scale have received much theoretical attention, and these extra dimensions could be tested at the LHC.
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