QFT: Is a^+_{-p}\ a_{-p} = a^+_{p}\ a_{p}?

[ananya J]

Homework Statement

Hi
I was trying to get the expression for H ,eqn 2.31 on page 21 peskins introductory QFT

Homework 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

 

[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? ;-)

 

[ananya J]

twas.