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dRic2
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In Landau-Lifsits's book about non relativistic QM it is said that if I have a particle described by a plane wave ##\phi = e^{ikz}## (I think he choses the ##z## direction for simplicity) the wave function after the scattering event is (far from the scattering event)
$$\psi \approx e^{ikz} + f(\theta) \frac{e^{ikr}} r$$
But then he said that the square value of ##\psi## is just ##|f(\theta)|^2## because we neglect the contribution of the first term (that is, we neglect some sort of interference phenomena). My first question is: then why bother says ##\psi = e^{ikz} + f(\theta) \frac{e^{ikr}} r## instead of simply putting ##\psi = f(\theta) \frac{e^{ikr}} r## ?
Then he says that the differential cross section is just ##|f(\theta)|^2## but I don't really follow the given explanation.
Can someone provide any hint?
Thanks
Ric
$$\psi \approx e^{ikz} + f(\theta) \frac{e^{ikr}} r$$
But then he said that the square value of ##\psi## is just ##|f(\theta)|^2## because we neglect the contribution of the first term (that is, we neglect some sort of interference phenomena). My first question is: then why bother says ##\psi = e^{ikz} + f(\theta) \frac{e^{ikr}} r## instead of simply putting ##\psi = f(\theta) \frac{e^{ikr}} r## ?
Then he says that the differential cross section is just ##|f(\theta)|^2## but I don't really follow the given explanation.
Can someone provide any hint?
Thanks
Ric