
#1
Jan813, 08:53 AM

P: 590

Hi all,
I've been reading section 5.3 of Peskin and Schroeder, in which the authors discuss the production of a bound state of a muonantimuon pair close to threshold in electronpositron collisions. Why does the matrix [itex]\Gamma[/itex] supposedly depend on the momentum of the nonrelativistic fermions? In their earlier analysis, this matrix was determined by the spins of the inital electronpositron pair, and the momentum of the final state muons dropped out even their Dirac spinors didn't depend on these momenta, only on the muon mass, which is why the scattering is isotropic. Thanks in advance. 



#2
Jan913, 12:13 AM

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PF Gold
P: 2,606





#3
Jan913, 04:34 AM

P: 590

Thanks for your reply fzero. The electrons necessarily have to be relativistic, in order to produce the muons; would this dependence on the final state momenta only become nontrivial if we were considering the scattering of fermions of comparable masses? (If the initial state particles were much heavier than those in the final state, then the process would obviously produce particles moving at relativistic velocities.)




#4
Jan913, 11:13 AM

Sci Advisor
HW Helper
PF Gold
P: 2,606

Production of bound states of slow fermions Peskin 5.3 


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