Neutrino flavour evolution through fluctuating matter

Abstract

A neutrino propagating through fluctuating matter can experience large amplitude transitions between its states. Such transitions occur in supernovae and compact object mergers due to turbulent matter profiles and neutrino self-interactions. In this paper we study, both numerically and analytically, three-flavour neutrino transformation through fluctuating matter built from two and three Fourier modes. We find flavor transformation effects which cannot occur with just two flavours. For the case of two Fourier modes we observe the equivalent of "induced transparency" from quantum optics whereby transitions between a given pair of states are suppressed due to the presence of a resonant mode between another pair. When we add a third Fourier mode we find a new effect whereby the third mode can manipulate the transition probabilities of the two mode case so as to force complete transparency or, alternatively, restore "opacity" meaning the perturbative Hamiltonian regains its ability to induce neutrino flavour transitions. In both applications we find analytic solutions are able to match the amplitude and wavenumber of the numerical results to within a few percent. We then consider a case of turbulence and show how the theory can be used to understand the very different response of a neutrino to what appears to be two, almost identical, instances of turbulence.

Matter parametric neutrino flavor transformation through Rabi resonances

“…It is also different than the threeflavor effect discussed in Ref. [19]. We have shown that an off-resonance Rabi mode can significantly change the parametric resonance of neutrino flavor conversion if the amplitude of the off-resonance mode is sufficiently large.…”

“…The interference between Rabi modes discussed here is different than the suppression of the parametric resonance by certain longwavelength Fourier modes which was discussed in Ref [17]. (see also footnote 1) and the three-flavor effect discussed in Ref [19]…”

“…Using the Jacobi-Anger expansion and the rotating wave approximation Kneller et al have shown that a parametric resonance can also occur when the neutrino oscillation frequency with the mean matter density matches a harmonic of the spatial frequency of * leima137@gmail.com † shashankshalgar@gmail.com ‡ duan@unm.edu the sinusoidal matter fluctuation [16]. This result has been generalized to the scenarios with matter fluctuations of multiple Fourier modes [17], slowly varying base profiles [18] and three-flavor neutrino mixing [19].…”

LUNA measurement found no evidence of a low-energy resonance in 6Li(p, γ)7Be reaction

“…In addition a Silicon (Si) detector was installed at 125 • from the beam direction to detect the α and 3 He particles from the 6 Li(p,α) 3 He reaction concurrently with the gamma rays from the 6 Li(p,γ) 7 Be reaction. Efficiencies for both detectors were obtained using GEANT simulations, fine tuned through the comparison with experimental results for γ and α standards as well as for known resonances of 14 N(p,γ) 15 O and 18 O(p,α) 15 N reactions [17]. The total uncertainty is 4% and 8% for the HPGe and Si detector efficiency respectively.…”

Turbulence fingerprint on collective oscillations of supernova neutrinos

“…Turbulence plays a crucial role in CCSNe [58][59][60][61][62]. The impact of turbulent density fluctuations on neutrino oscillations has been extensively studied in 1D models [63][64][65][66][67][68][69][70][71][72][73], where it can induce flavor conversions through parametric resonances. Here, we demonstrate that the presence of turbulence in CCSNe can also induce collective neutrino flavor conversion modes via an entirely different mechanism, i.e., the leakage of flavor instabilities between different Fourier modes.…”