Code comparison for fast flavor instability simulations

The fast flavor instability (FFI) is expected to be ubiquitous in core-collapse supernovae and neutron star mergers. It rapidly shuffles neutrino a way that could impact the explosion mechanism, signals, mass outflows, nucleosynthesis. variety of initial conditions simulation methods employed simulations FFI prevent an apples-to-apples comparison results. We simulate standardized test problem using five independent codes verify they are all faithfully simulating underlying quantum kinetic equations under assumptions axial symmetry homogeneity two directions. quantify amount numerical error each method demonstrate superior at least one metric this error. make results publicly available serve as benchmark.