Toward a new theory
Despite active research in the past decade, no hint to a theory ``beyond the Standard Model'' has been found. The reason is that the phenomena they govern appear only at energies higher than what has been reached so far with current particles accelerators.
To reach the energies of these new theories one needs a more powerful accelerator. At the moment there are 2 leading kinds of high energy particles collider. The first kind, called hadronic collider, smashes 2 protons on each other. The energy that can be released during these collisions is very high (at the scale of particle physics) but as the protons are composite particles many spectator particles are released during the collision and it is harder to isolate the particles that played a key role in the reaction. The second kind of collider (called a leptonic collider) smashes electrons onto their antiparticle counterparts (positrons). These two particles completely disappear in the process releasing all their energy for the production of new particles. Thus the reactions produced by such colliders are much ``cleaner'' but the energy reach is limited because it is much harder to accelerate electrons at very high energies.
A new hadronic collider called ``Large Hadron Collider'' (LHC) is being built at CERN on the Swiss-French border near Geneva. Particle physicists hope to discover the Higgs boson at the LHC as well as some new particle predicted by one of the models beyond the Standard Model. But they also know that they will not be able to measure precisely the properties of these particles because the collisions in an Hadronic collider have too many ``spectator'' particles.
To be able to measure precisely the properties of the new particles discovered at the LHC they will need a new leptonic collider.
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Last modified: "Sep 16 2003"
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