Sterile neutrinos are a type of neutrino that has been hypothesized as a possible explanation for some surprising experimental results, although they have yet to be confirmed. Scientists are scouring the globe for them in a variety of tests.
While electron, muon, and tau neutrinos (and antineutrinos) interact with matter via two forces (weak force and gravity), scientists believe sterile neutrinos may solely interact via gravity. This would make them even more difficult to detect than the perplexing “normal” neutrinos. Gravity is the weakest of all the forces, and neutrinos are extremely light, thus gravity has nothing to work with. Finding faint signals in the midst of the universe’s chaos will be difficult, but not impossible.
While scientists are aware of the three types of neutrinos, they are unsure how many sterile neutrinos exist. Is there only one to include, or are there three in parallel? Or there could be much more!
Spin and helicity are properties of particles, notably the strange neutrino. Although the particles do not really spin like a top, this is a useful metaphor. Helicity describes how the spin of a particle interacts with its movement, and it’s similar to being left-handed or right-handed.
Make two fists with your hands outstretched. Your thumb points in the direction of movement, and your fingers curve to symbolize a particle’s spin. These are right-handed and left-handed particles, and they’re significant because the weak force, one of nature’s four forces, does not regard them equally. The weak force tends to interact with particles that are left-handed.
Only left-handed neutrinos have been discovered so far. Right-handed neutrinos, on the other hand, could be the expected sterile neutrinos. Sterile (right-handed) neutrinos would interact only through gravity because the weak force would ignore them, making them nearly invisible.
Oscillation is one method for locating these elusive particles. Excess neutrino oscillations have been seen in several studies when theory indicated they shouldn’t be. In several investigations, neutrinos appeared or disappeared over considerably shorter distances than neutrinos from more distant places, such as the atmosphere or the sun. If neutrinos oscillate into this fourth type of particle, the quick shifts and abnormalities observed in experiments could be explained. Before anything can be decided definitively, much more data is required.