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Difference between 2to2 interactions

by ChrisVer
Tags: 2to2, difference, interactions
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ChrisVer
#1
Jun8-14, 04:59 PM
P: 1,066
What is the difference between these interactions?
[itex] a+b \rightarrow c+d[/itex]
and
[itex] b+a \rightarrow d+c [/itex]
?

I was reading the "State-of-the-art formulas for helicity amplitude calculation and all that" ver 2.4, part Ia. - Spherical-vector method for helicity amplitudes (Formalism), by Ken-Ichi Hikasa.
In the discrete symmetry and helicity amplitudes sector (pg 5) he gives different invariant matrices [itex]M[/itex] forms for these two above.
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Hepth
#2
Jun9-14, 07:08 AM
PF Gold
Hepth's Avatar
P: 472
Are you SURE there is no difference between the notation in the two equations, ONLY the ordering? (such as a helicity index change?) He doesn't reference two different diagrams? (s and t channel?)


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