NuSQuIDS: A toolbox for neutrino propagation

Abstract

The Neutrino Simple Quantum Integro-Differential Solver (nuSQuIDS) is a C++ code based on SQuIDS that propagates an ensemble of neutrinos through given media. Neutrino oscillation calculations relevant to current and next-generation experiments are implemented. This includes coherent and non-coherent neutrino interactions in settings such as the Sun, Earth, or a vacuum. The code is designed to be accurate and flexible, while at the same time maintaining good performance. It has a modular design that allows the user to incorporate new physics in novel scenarios. Program summaryProgram title: Neutrino Simple Quantum Integro-Differential SolverCPC Library link to program files:https://doi.org/10.17632/fb66sr79dz.1Developer's repository link:https://github.com/arguelles/nuSQuIDSLicensing provisions: LGPLProgramming language: C++ with optional Python interfaceNature of problem: The evolution of neutrino fluxes includes both coherent flavor changes (oscillations) and non-coherent scattering interactions with matter. Calculating both types of phenomena is necessary for some studies in neutrino physics, and even in cases where it is not required it is convenient to have a full physics description available in a single package.Solution method: The Simple Quantum Integro-Differential Solver (SQuIDS) [1,2] is used to decompose neutrino fields with SU(N) algebras and solve for their evolution with standard ODE solvers (via the GNU Scientific Library [3]). The evolution of the flavor/mass eigenstate relationships are kept updated in parallel with the ODE solution, as are interaction effects with matter. Users may add new material profiles and physics effects.Additional comments including restrictions and unusual features: Vacuum oscillations are computed analytically, simplifying the ODE problem to be solved. This package supports additions to the neutrino flux over the full course of its evolution, allowing direct treatment of extended sources, and averaging of fast oscillations which cannot be experimentally resolved. The package does not currently implement the complex neutrino interactions relevant at low (O(10 GeV)) neutrino energies.