Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userCollective Oscillations of Majorana Neutrinos in Strong Magnetic Fields and Self-induced Flavor Equilibrium
61
0
0.0
(
0
)
Authors
Sajad Abbar
Ask ChatGPT about the research
No Arabic abstract
We study collective oscillations of Majorana neutrinos in some of the most extreme astrophysical sites such as neutron star merger remnants and magneto-rotational core-collapse supernovae which include dense neutrino media in the presence of strong magnetic fields. We show that neutrinos can reach flavor equilibrium if neutrino transition magnetic moment $mu_ u$ is strong enough, namely when $mu_ u/mu_{rm{B}} gtrsim 10^{-14}-10^{-15}$ with $mu_{rm{B}}$ being the Bohr magneton. This sort of flavor equilibrium, which is not necessarily flavor equipartition, can occur on (short) scales determined by the strength of the magnetic term. Our findings can have interesting implications for the physics of such violent astrophysical environments.
rate research
Read More
We bring to light a novel mechanism through which turbulent matter density fluctuations can induce collective neutrino flavor
We study the evolution of massive mixed Dirac and Majorana neutrinos in matter under the influence of a transversal magnetic field. The analysis is based on relativistic quantum mechanics. We solve exactly the evolution equation for relativistic neutrinos, find the neutrino wave functions, and calculate the transition probability for spin-flavor oscillations. We analyze the dependence of the transition probability on the external fields and compare the cases of Dirac and Majorana neutrinos. The evolution of Majorana particles in vacuum is also studied and correction terms to the standard oscillation formula are derived and discussed. As a possible application of our results we discuss the spin-flavor transitions in supernovae.
We simulate neutrino-antineutrino oscillations caused by strong magnetic fields in dense matter. With the strong magnetic fields and large neutrino magnetic moments, Majorana neutrinos can reach flavor equilibrium. We find that the flavor equilibration of neutrino-antineutrino oscillations is sensitive to the values of the baryon density and the electron fraction inside the matter. The neutrino-antineutrino oscillations are suppressed in the case of the large baryon density in neutron (proton)-rich matter. On the other hand, the flavor equilibration occurs when the electron fraction is close to $0.5$ even in the large baryon density. From the simulations, we propose a necessary condition for the equilibration of neutrino-antineutrino oscillations in dense matter. We also study whether such necessary condition is satisfied near the proto-neutron star by using results of neutrino hydrodynamic simulations of core-collapse supernovae. In our explosion model, the flavor equilibration would be possible if the magnetic field on the surface of the proto-neutron star is larger than $10^{14}$ G which is the typical value of the magnetic fields of magnetars.
We investigate collective flavor oscillations of supernova neutrinos at late stages of the explosion. We first show that the frequently used single-angle (averaged coupling) approximation predicts oscillations close to, or perhaps even inside, the neutrinosphere, potentially invalidating the basic neutrino transport paradigm. Fortunately, we also find that the single-angle approximation breaks down in this regime; in the full multiangle calculation, the oscillations start safely outside the transport region. The new suppression effect is traced to the interplay between the dispersion in the neutrino-neutrino interactions and the vacuum oscillation term.
We give a very brief overview of collective effects in neutrino oscillations in core collapse supernovae where refractive effects of neutrinos on themselves can considerably modify flavor oscillations, with possible repercussions for future supernova neutrino detection. We discuss synchronized and bipolar oscillations, the role of energy and angular neutrino modes, as well as three-flavor effects. We close with a short summary and some open questions.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
