Find the spectrum of the 2nd excited states.

Homework Statement

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.

Homework Equations

I don't know much.