# Oscillations: Neutral Kaon vs neutrino

1. Mar 11, 2010

### Dmitry67

I understand that
$$K_l = \frac{d\bar{s} + s\bar{d}}{\sqrt{2}}$$
$$K_s = \frac{d\bar{s} - s\bar{d}}{\sqrt{2}}$$
This happens because $$K_0$$ is oscillating into its own antiparticle.
My question is, why the same is not applicable to the neutrinos? They do oscillate. So instead of ‘pure’ e, mu, tau neutrinos we do not observe superposition?

2. Mar 11, 2010

### ansgar

We detect mass eigenstates of neutrinos, but a mass eigenstate is a mixture of weak eigenstates. Similar for quarks, their mass and weak eigenstates are not the same.

3. Mar 11, 2010

### chrispb

We DO observe superpositions; we observe one of three mass eigenstates, each of which is a linear superposition of flavors.

4. Mar 11, 2010

### clem

In each case, the mass eigenstate propagates, but the particle eigenstate (d sbar or
say e-neutrino) interacts in the weak interaction. The time scales are different.
When you say "observe" that is the weak interaction.

5. Mar 11, 2010

### ansgar

that is correct, i mixed them up. Sorry OP

6. Mar 11, 2010

### Dmitry67

So your thoughts are in superposition? :)

Thank you