Model building (particle physics)

In particle physics, the term model building refers to a construction of new quantum field theories beyond the Standard Model that have certain features making them attractive theoretically or for possible observations in the near future. If the model building physicist uses the tools of string theory, he or she is called "superstring model builder".

A model builder typically chooses new quantum fields and their new interactions, attempting to make their combination realistic, testable and physically interesting. In particular, an interestingnew model should address questions left unanswered in the Standard Model which has, including three massive neutrinos, 28 free parameters. A model which extends the Standard Model should predict one or more of these parameters or shed light on some other issue such as why there are three quark-lepton families or, the most common motivation, the naturalness or hierarchy problem associated with the quadratic divergences appearing in the scalar sector.

The work of model builders

Model builders constitute a group between experimentalists and "pure" theorists; model builders are theorists, but with an emphasis on using current tools to fit data, in addition to the more long-term pursuit of a more complete theory of nature. Model builders are one step closer to pure theorists than phenomenologists are, although the distinction is often blurred in practice.

Model building is speculative because current particle......
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