Speaker
Description
Neutrino oscillations are experimentally established, yet their description within quantum field theory remains conceptually subtle—particularly how to define the oscillating one-particle neutrino state. Many formulations recover the phenomenology by introducing the coherent production of flavour states as superpositions of mass eigenstates and by modeling production/detection with external wave packets; our framework requires neither.
In our approach flavour neutrinos are treated as massless at weak interaction vertices as in the Standard Model, while a feeble flavour-violating Yukawa coupling to the Higgs vev background field influences their propagation via coherent forward, flavour-mixing scattering. Motivated by optical birefringence, we interpret the Higgs vev background field—and any matter background—as a refractive medium in which multiple forward-scattering leads to differing phase accumulation and mixing. In the medium the flavour neutrinos obey a relativistic flavour-mixing wave equation governed by an index-of-refraction matrix.
This equation reproduces the standard oscillation probabilities in vacuum, the MSW effect, and adiabatic flavour conversion in slowly varying density profiles. In addition, the refractive description naturally defines an effective “refractive mass” and a unique group velocity for the oscillating neutrino state at fixed energy, yielding a well-defined time-of-flight interpretation and ensuring the coherence of the flavour states. The poster will present the derivation, the mapping to standard oscillation phenomenology, and the conceptual and phenomenological distinctions of the refractive-vacuum approach.