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forrealfyziks
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Homework Statement
The positive pion decays into a muon and a neutrino. The pion has rest mass m=140 MeV/c^2, the muon has m=106 MeV/c^2 while the neutrino is about m=0 (assume it is). Assuming the original pion was at rest, use conservation of energy and momentum to show that the speed of the muon is given by
U/c = [(m[tex]\pi[/tex]/m[tex]\mu[/tex])2 - 1] / [(m[tex]\pi[/tex]/m[tex]\mu[/tex])2 + 1]
Homework Equations
For massless particles, E=pc u=c [tex]\beta[/tex]=1
p=[tex]\gamma[/tex]mu E=[tex]\gamma[/tex]mc2
The Attempt at a Solution
(Note [tex]\gamma[/tex] and u are for mu, since it's the only particle using them)Alright, I know that P[tex]\pi[/tex]=0 and P[tex]\mu[/tex]+P[tex]\nu[/tex]=0. I found that P[tex]\nu[/tex]=-[tex]\gamma[/tex]m[tex]\mu[/tex]u[tex]\mu[/tex]
I replace p in m[tex]\pi[/tex]c2=P[tex]\nu[/tex]c + [tex]\gamma[/tex]m[tex]\mu[/tex]c2 and reduced it down and got
m[tex]\pi[/tex]c=[tex]\gamma[/tex]m[tex]\mu[/tex](c-u)
I then unraveled the gamma, moved some stuff around, and squared both sides and got (m[tex]\pi[/tex]/m[tex]\mu[/tex])2=(c-v)2/(1-v2/c2)
I don't know if this is the right path, but I have tried many different methods from this point and nothing seems to get any closer to what I need. Thanks for any help.