Which neutrino has the smallest mass?

The question surrounding neutrino mass extends beyond how much they weigh to which one is the lightest.

We know that neutrinos come in three flavors: electron, muon, and tau neutrinos. However, there are three types of mass neutrinos: v1, 2, and 3, which are also known as mass 1, mass 2, and mass 3. Life would be simple—but boring—if each flavor of neutrino corresponded to a distinct mass. Neutrinos are difficult to understand, and it turns out that the mass and flavor neutrinos do not perfectly overlap.

Quantum mechanics, on the other hand, comes into play. Each flavor of neutrino is made up of a mixture of neutrinos with different masses. As a result, each neutrino with a given mass has a chance of interacting with a specific flavor. 1 is quite likely to interact as an electron neutrino, for example.

The most crucial thing to know about this issue is that scientists have no idea whether neutron 3 is considerably heavier or lighter than the other two mass states. It would be a major surprise if it was the lightest!

Neutrino physicists frequently discuss two scenarios for neutrino mass distribution. (The term “hierarchy” is sometimes used to describe the ordering of neutrino masses.)

1 is the lightest, 2 is the middle-weight, and 3 is the heaviest in the “standard mass ordering.” Because the masses of the particles associated with neutrinos are mirrored, this is called normal. Because the electron is significantly lighter than the muon and tau particles, it seems natural that the mass neutrino that normally manifests as an electron neutrino would also be lighter. To put it another way, the electron neutrino is largely made up of the lightest of the mass states, the neutrino mass state.

The “inverted mass ordering,” in which the 3 neutrino is the lightest, is the other option. The 1 neutrinos aren’t the lightest of all, which means electron neutrinos aren’t comprised of the lightest mass state. Alternatively, the electron neutrino is primarily composed of one of the heavier neutrino mass states. What a way to turn particles on their heads!

Scientists can use experiments that look at how neutrinos vary over great distances to see if they come in the usual or inverted mass ordering. Certain neutrino oscillations (flavor shifts) should occur at a faster pace in the regular world than in the inverted world.

Neutrinos are observed in three varieties that correspond to the leptons created when neutrinos interact (electron, muon, and tau). The three neutrino flavors are quantum mechanical combinations of three neutrino mass states, according to the simplest explanation for neutrino flavor change. As a result, neutrinos move as a mixture of the three mass states rather than as a single, unchanging flavor.

Each of the mass states has a chance of reacting in the form of one of the tastes.

One mass state (v1) will interact two-thirds of the time as an electron neutrino and one-third of the time as a muon or tau neutrino.
A third of the time, another mass state (2) will interact as any of the three flavors.

The final mass state (3) will interact 45 percent of the time as a muon or tau neutrino, and ten percent of the time as an electron neutrino.
The speed at which the three mass neutrinos migrate determines the likelihood that the neutrino flavor at the point of interaction differs from the flavor at the point of production. Because if neutrinos were massless, they would all move at the speed of light, this fact tells scientists that they have mass and that those masses are different.