# Peskin QFT p.21

1. Jan 1, 2009

### ananya J

1. The problem statement, all variables and given/known data
Hi
I was trying to get the expression for H ,eqn 2.31 on page 21 peskins introductory QFT
2. Relevant equations
I get the final expression only if $$a^+_{-p}\ a_{-p}$$ = $$a^+_{p}\ a_{p}$$
so pls tell me if $$a^+_{-p}\ a_{-p}$$ = $$a^+_{p}\ a_{p}$$
(+ stands for dagger) thanks in advance

Last edited: Jan 1, 2009
2. Jan 1, 2009

### malawi_glenn

don't you think it is a good exercise to rewrite the creation/annihilation operators in terms of phi and pi fields and then find out the relation for yourself? ;-)

3. Jan 1, 2009

twas.