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Physics with ATLAS: The Higgs Particle

One of the main goals of the ATLAS program is to discover and study the Higgs particle. The Higgs particle is of critical importance in particle theories and is directly related to the concept of particle mass and therefore to all masses. What is the Higgs particle?

The Riddle of Mass

Why do the fundamental particles have mass, and why are their masses different? It is remarkable that a concept as familiar as mass was not understood until the proposal of the Standard Model.

Most of us are familiar with electric, magnetic, and gravitational fields. A person in Earth's gravitational field feels a force. Electromagnetic waves (such as radio waves) travel through space in the same way that ripples in a pond travel through water. If the pond was described in quantum language, the water surface that carries the waves would be called a "field".

The Standard Model proposed that there is another field never before observed, a field that is almost indistinguishable from empty space. We call this the Higgs field. We think that all of space is filled with this field, and that by interacting with this field, particles acquire their masses. Particles that interact strongly with the Higgs field are heavy, while those that interact weakly are light.

The Higgs field has at least one new particle associated with it, the Higgs particle (or Higgs boson). The ATLAS detector at the LHC will be able to detect this particle if it exists. This would be one of the greatest scientific discoveries.

On the next page, the Higgs mechanism is revealed !