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Why we use the trace calculation?

by Hluf
Tags: calculation, trace
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Hluf
#1
Mar11-14, 02:36 AM
P: 22
Dear all
When we calculating the cross section of particles, we apply the trace calculation. This is not clear for me, why we use the trace calculation?
Thank you all.
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dauto
#2
Mar11-14, 08:48 AM
Thanks
P: 1,948
The trace averages over many possible initial states. Useful when the initial state is not known or the beam of particles contains a mixture of states.
dauto
#3
Mar11-14, 08:56 AM
Thanks
P: 1,948
Also, if you're talking about intermediary (virtual) particles than taking the trace ensures that all possible intermediary states are taken into account.


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