Theoretical Elementary Particle Physics
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| A little theoretical physics. |
As early as 1974, theorists had essentially formulated the Standard Model of particle physics and had taken it about as far as they could with the evidence available from experiment. It would be decades before experimentalists would be able to begin either work on the unsolved mysteries of the Standard Model, such as the existence of the hypothetical Higgs Boson; or begin testing physics beyond the Standard Model. Indeed, the technological ability to do these experiments is a contemporary development, which will hopefully be borne out in huge collaborations such as the Compact Muon Solenoid at the Large Hadron Collider in Geneva, slated to begin operation this decade.
Professor Mikhail Voloshin is a Minnesota theorist whose main interests lie in the unresolved questions of the Standard Model, such as the interplay of strong and electroweak interactions in heavy quark physics.
Another way in which high energy theorists such as Professor Keith Olive have worked, without much experimental data from accelerators, is to apply their knowledge of elementary particle interactions to astrophysics and cosmology. For example, the process through which the light elements were formed in the early Universe, called Big Bang Nucleosynthesis, can be used to place constraints on the Standard Model. Olive and his group have also used data from accelerator runs at CERN to place strong constraints on the possible properties of dark matter.
Professor Tom Walsh's interest has recently focused on lattice gauge theories that provide a concrete numerical approach to attain a quantitative understanding of the strong interactions.
The bulk of theoretical efforts in elementary particle physics focus on the possibilities of physics beyond the Standard Model. To go beyond the Standard Model, theorists have been using a hypothetical construct known as Supersymmetry (SUSY). SUSY states that at some level, processes involving bosons (integer-spin particles) and fermions (one-half integer spin particles) are indistinguishable. In the real world of the Standard Model, these two classes of particles are very different. In order for bosons and fermions to be at some level indistinguishable, Supersymmetry postulates that each particle has its own superpartner of unknown mass and identical Standard Model quantum numbers. As experimentalists search for hard evidence of superpartners, Minnesota theorists such as Tony Gherghetta, Serge Rudaz, Mikhail Shifman and Arkady Vainshtein continue to explore the properties of Supersymmetry.
It is remarkable that the idea of Supersymmetry has lead to deeper understandings of the properties of quantum field theory, the descriptive framework of elementary particle physics, in spite of the (to date) absence of concrete evidence in its favor. Some theorists at Minnesota, such as Tony Gherghetta and Mikhail Shifman go even beyond these speculative ideas to visionary constructs such as extra dimensions and brane worlds.
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