1. The problem statement, all variables and given/known data consider the space-time transformation of translation xμ → x'μ = xμ + aμ where xμ is a point in space-time and aμis a constant 4-vector. Assuming translations are generated by the operator U=e-iPμaμ acting on fields Φ(x), derive the representation of Pμ on the field Φ(x). 2. Relevant equations 3. The attempt at a solution From looking at it I would assume it would look something like i∂μΦ Though if this is the case I'm not entirely sure why.