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Hi everybody,

i'm worried about some calculation. I have to write down the amplitude for the neutral Kaon oscillation. There are two Box diagrams which are depicted here:

http://upload.wikimedia.org/wikipedia/de/9/92/FeynmanKaon.png [Broken]

The two diagrams come along with a combinatorical factor of 1/2 and they have a relative sign according to the possible contractions.

Now I get for diagram on the left with W-exchange in (\xi =1) gauge up to some constants the following dirac structure (external momenta neglected)

[\bar(s) \gamma_{\mu} (\slashed{k} + m_1) \gamma_{\nu} d] \otimes

[\bar(s) \gamma_{\nu} (\slashed{k} + m_2) \gamma_{\mu} d]

Now, wenn calculating the right diagram, i get basically the same, which together with the relative sign would give a vanishing full amplitude.

Does anybody know, what i am doing wrong ?

i'm worried about some calculation. I have to write down the amplitude for the neutral Kaon oscillation. There are two Box diagrams which are depicted here:

http://upload.wikimedia.org/wikipedia/de/9/92/FeynmanKaon.png [Broken]

The two diagrams come along with a combinatorical factor of 1/2 and they have a relative sign according to the possible contractions.

Now I get for diagram on the left with W-exchange in (\xi =1) gauge up to some constants the following dirac structure (external momenta neglected)

[\bar(s) \gamma_{\mu} (\slashed{k} + m_1) \gamma_{\nu} d] \otimes

[\bar(s) \gamma_{\nu} (\slashed{k} + m_2) \gamma_{\mu} d]

Now, wenn calculating the right diagram, i get basically the same, which together with the relative sign would give a vanishing full amplitude.

Does anybody know, what i am doing wrong ?

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