When I read quantum field theory in Weinberg's Volume 1. In equation 2.6.22 :(adsbygoogle = window.adsbygoogle || []).push({});

[tex]P{\Psi _{p,\sigma }} = {\eta _\sigma }\exp ( \mp i\pi \sigma ){\Psi _{{\cal P}p,{-\sigma} }}[/tex]

I don't agree with the [tex]-\sigma[/tex] in the result of space reversal transformation.

Can any one explain it for me?

Thanks

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# One stupid question about Weinberg's Volume 1

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