PHY 6648: Quantum Field Theory I
Fall Term 2005
Homework Set 3
Due Friday, September 16 2005
Reading: Section 2.3 from the textbook and class notes.
Problem 1. The total momentum operator. Use (2.27-2.29) and derive (2.33) in a
manner analogous to the derivation of (2.31) in class. Did you encounter an infinite constant
along the way? (Recall that to make sense of the Hamiltonian operator, we had to sweep under
the rug an infinite constant.) Does the answer for P~ suffer from a similar ambiguity? Explain
why or why not.
Problem 2. Lorentz-invariant measure. Prove (2.40) from Peskin&Schroeder.
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