  In this study, a novel theory to investigate the mass oscillation of
particles is proposed. It has been proven that, at high-energy conditions, the
fermion field described by Dirac Lagrangian interacts with the half-integer
spin tachyon field with negative energy, causing the formation of composite
particles whose mass depends on the total angular momentum. The proposed theory
is based on a new interpretation of the Majorana equation for particles with
arbitrary spin and shows that mass oscillation is a phenomenon in which the
component of particle decay prevails over that of mixing mass states. Using the
kinematic of Lemke for spacelike particle decay, we propose a mechanism able to
explain the neutrino flavour change. The proposed mechanism is also
investigated concerning the shape of its spectrum. Finally, the Lagrangian
field of composite particles is formulated.
