On the emergence of physics beyond the Standard Model from right-handed neutrinos
Publication Date
December 31, 2025
Creator
Abstract
Sakharov's induced gravity is a semiclassical mechanism where classical spacetime dynamics emerge from quantised matter fields. In this thesis, we find the Lagrangian terms from Sakharov's induced gravity where the matter fields are exclusively right-handed neutrinos. The right-handed neutrino induced terms consist of two main types: gravitational and fermionic. Our key result from the gravitational piece is a Newton constant that is consistent with observation, whence it is possible for the Einstein-Hilbert action to be an emergent consequence of right-handed neutrinos alone. We also obtain a cosmological constant and gravitational couplings of curvature-squared order, but these are incompatible with existing bounds and can be discarded. The fermionic piece leads to a seesaw mechanism, which gives active (left-handed) and sterile (right-handed) neutrino masses. The active neutrino masses turn out to be consistent with experimental data, but this comes at the expense of naturalness and staying within the perturbative coupling domain. The sterile neutrino masses lead to a potential neutrino dark matter candidate. Hence, we observe that right-handed neutrino induced gravity accounts for the combination of realistic spacetime dynamics, neutrino masses and a dark matter candidate, which is unaccounted for by the Standard Model. The right-handed neutrino induced Einstein-Hilbert term in particular further motivates right-handed neutrino existence.
In the non-commutative formulation of geometry due to Connes, coordinates under multiplication do not commute. A simple matrix model within Connes' non-commutative geometry is considered. It is observed that the full action of this model is emergent in a manner akin to Sakharov's induced gravity. In the model, this induced gravity perspective provides further explanation for a non-commutative geometry principle which is a stronger version of diffeomorphism-invariance at the level of the action. The findings are restricted to our model and constitute work in progress. It is hoped that non-commutative geometry will gain more understanding due to the induced gravity perspective.
Item Type
ethesis
Thesis Type
PhD
Supervisors
Subjects (LC)
Associated Schools / Departments
School of Mathematical Sciences (UK)
eprints ID
81299
UoN Repository URI
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Nagen, Alexander, 20313757, corrections.pdf
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