# Energy Eigenstates of the Hamiltonian

1. Operator Algebra. Evaluate the following expressions:

See attached for equations

Neutrino Oscillation made oversample. Neutrinos come in three varieties that we know of: the electron neutrino (V_e) the tau neutrino (V_T) and the muon neutrino (which is irrelevant to this problem). Nuclear fusion in the sun's interior produces electron neutrino. A major problem describes (in a super simplified way) one possible explanation.

Suppose the Hamiltonian of the sun (which describes the interaction of neutrinos with the rest of the sun) can be described as follows:

(See attached)

Find the energy eigenstates of this Hamiltonian in terms of the "basis vectors" (V_e) and (V_T), and the corresponding energy eigenvalues.

Suppose that t = 0, an electron neutrino (V_e) is produced in the center of the sun. What is the state at time t > 0, in terms of the parameters a and b?

What is the probability that the original electron neutrino will be observed as a tau neutrino at time t?

#### Solution Preview

First, let's recall that in the eigenbasis of we have:

(1.1)

Now let's consider the translation operator:

(1.2)

For small a we can express the right hand side as a Taylor series:

(1.3)

But this can be also written as:

(1.4)

Hence:

(1.5)

But we know that in the coordinate space we have:

(1.6)

Thus:

(1.7)

By the same token:

(1.8)

And:

(1.9)

When we apply the operators and consecutively we get:

Hence:

(1.10)

So the basis is also an eigenbasis for and applying it on the eigenbasis yields the coordinate shifted by ...

#### Solution Summary

The expert evaluates an expression for operator algebra.