Neutrino Propagation When Mass Eigenstates and Decay Eigenstates Mismatch

Area of Science:

• Particle Physics
• Neutrino Physics
• Cosmology

Background:

• The behavior of neutrinos propagating through matter is crucial for understanding neutrino oscillations and decay.
• Simultaneous diagonalization of Hermitian and anti-Hermitian components of the effective Hamiltonian is often assumed but not universally applicable for decaying neutrinos.
• Existing models face challenges in accurately describing neutrino survival and conversion probabilities under various matter densities.

Purpose of the Study:

• To investigate the limitations of simultaneous diagonalization for decaying neutrinos in matter.
• To develop a novel formalism for two-flavor neutrino propagation with decay into invisible states.
• To derive analytic expressions for neutrino survival and conversion probabilities.

Main Methods:

• Developed a new theoretical formalism for two-flavor neutrino propagation through uniform density matter.
• Incorporated neutrino decay into invisible states within the formalism.
• Employed a resummation of the Zassenhaus expansion to derive analytic results.

Main Results:

• Demonstrated that Hermitian and anti-Hermitian components of the effective Hamiltonian cannot always be simultaneously diagonalized.
• Obtained compact analytic expressions for neutrino survival and conversion probabilities.
• Results are presented to first and second order in the mismatch parameter γ[over ¯].

Conclusions:

• The developed formalism provides a more accurate description of decaying neutrino propagation in matter.
• The analytic expressions offer a valuable tool for theoretical calculations and experimental interpretations in neutrino physics.
• This work advances our understanding of neutrino properties and their interactions in dense media.