Phase-Space methods for neutrino oscillations: extension to multi-beams

TL;DR

This paper extends the phase-space approach to neutrino oscillations, enabling efficient simulation of many beams and neutrinos, capturing many-body effects, and bridging microscopic and transport models.

Contribution

The paper introduces a new sampling method within the phase-space approach that allows modeling an arbitrary number of neutrino beams and neutrinos efficiently.

Findings

Successfully validated the method against exact calculations.

Able to simulate up to 200 beams with complex Hamiltonians.

Captures many-body effects like entanglement and dissipation.

Abstract

The Phase-Space approach (PSA), which was originally introduced in [Lacroix et al., Phys. Rev. D 106, 123006 (2022)] to describe neutrino flavor oscillations for interacting neutrinos emitted from stellar objects is extended to describe arbitrary numbers of neutrino beams. The PSA is based on mapping the quantum fluctuations into a statistical treatment by sampling initial conditions followed by independent mean-field evolution. A new method is proposed to perform this sampling that allows treating an arbitrary number of neutrinos in each neutrino beam. We validate the technique successfully and confirm its predictive power on several examples where a reference exact calculation is possible. We show that it can describe many-body effects, such as entanglement and dissipation induced by the interaction between neutrinos. Due to the complexity of the problem, exact solutions can only be calculated for rather limited cases, with a limited number of beams and/or neutrinos in each beam. The PSA approach considerably reduces the numerical cost and provides an efficient technique to accurately simulate arbitrary numbers of beams. Examples of PSA results are given here, including up to 200 beams with time-independent or time-dependent Hamiltonian. We anticipate that this approach will be useful to bridge exact microscopic techniques with more traditional transport theories used in neutrino oscillations. It will also provide important reference calculations for future quantum computer applications where other techniques are not applicable to classical computers.