Licentiate thesis: Predictions of Effective Models in Neutrino Physics
by
Johannes Bergström(Department of Theoretical Physics, KTH)
→
Europe/Stockholm
FB53
FB53
Description
Experiments on neutrino oscillations have confirmed that neutrinos have
small, but non-zero masses, and that the interacting neutrino states do
not have definite masses, but are mixtures of such states.
The seesaw models make up a group of popular models describing the small
neutrino masses and the corresponding mixing. In these models, new,
heavy fields are introduced and the neutrino masses are suppressed by
the ratio between the electroweak scale and the large masses of the new
fields. Usually, the new fields introduced have masses far above the
electroweak scale, outside the reach of any foreseeable experiments,
making these versions of seesaw models essentially untestable. However,
there are also so-called low-scale seesaw models, where the new
particles have masses above the electroweak scale, but within the reach
of future experiments, such as the LHC.
In quantum field theories, quantum corrections generally introduce an
energy-scale dependence on all their parameters, described by the
renormalization group equations. In this thesis, the energy-scale
dependence of the neutrino parameters in two low-scale seesaw models,
the low-scale type I and inverse seesaw models, are considered.
Also, the question of whether the neutrinos are Majorana particles, i.e., their own antiparticles, has not been decided experimentally. Future
experiments on neutrinoless double beta decay could confirm the Majorana
nature of neutrinos. However, there could also be additional
contributions to the decay, which are not directly related to neutrino
masses. We have investigated the possible future bounds on the strength
of such additional contributions to neutrinoless double beta decay,
depending on the outcome of ongoing and planned experiments related to
neutrino masses.
