In theoretical physics
, the seesaw mechanism
is a mechanism within grand unification theory
, and in particular in theories of neutrino
masses and neutrino oscillation
, where it can be used to explain the smallness of observed neutrino masses relative to those of quarks
There are several varieties commonly referred to as type 1 seesaw, type 2 seesaw etc. The simplest version, type 1, requires as additional assumptions to the standard model
only two or more right-handed neutrino fields, and the existence of a very large mass scale in the theory which can for example be the scale of grand unification.
Type 1 seesaw
This model produces a light neutrino, corresponding to the three known neutrino flavors, and a very heavy, undiscovered sterile neutrino
, which has possibly been detected.
The mathematics behind the seesaw mechanism is the following fact: the 2 by 2 matrix
- <math>A = begin0&M\M&Bend text</math>
where <math>B</math> is much larger than <math>M</math>, has the following eigenvalues
- <math>lambda_pm = frac text</math>
The larger eigenvalue is approximately equal to <math>B</math> while the smaller eigenvalue is approximately equal to
- <math>lambda_- approx...