Find the spectrum of the 2nd excited states.

1. Jun 10, 2013

rbwang1225

1. The problem statement, all variables and given/known data
A state at the 2nd exited level is of the form:
$|\epsilon>=(\epsilon_{\mu\nu}\alpha^\mu_{-1}\alpha^\nu_{-1}+\epsilon_{\mu}\alpha^\nu_{-2})|0;p>$
Find the spectrum of the 2nd excited states, the value of the mass squared, the condition for the state to be physical, and the gauge symmetry transformation due to null states.

2. Relevant equations
I don't know much.

3. The attempt at a solution