 Mikheyev–Smirnov–Wolfenstein effect

The Mikheyev–Smirnov–Wolfenstein (MSW) effect is a phenomenon in particle physics that describes the matter effects on the oscillation of neutrinos as they propagate through matter, such as in the Earth or the Sun. It helps to explain how neutrinos change from one flavor to another—a process known as neutrino oscillation—when they pass through dense media.