Particle Creation
المؤلف:
Sidney B. Cahn And Boris E. Nadgorny
المصدر:
A GUIDE TO PHYSICS PROBLEMS
الجزء والصفحة:
part 1 , p 40
13-7-2016
1531
Particle Creation
Consider a photon of energy εγ incident on a stationary proton. For sufficiently large εγ, aπ meson can be produced in a reaction
What is εmin the threshold photon energy for this reaction to occur?
SOLUTION
In this problem and in most of the problems involving particle reactions, we will use units where c = 1. Compose the invariant quantity for the system pμ pμ. Before the reaction in the rest frame of the proton
(1)
(2)
where we used pγ = εγ. After the reaction, in the center of mass frame, the lowest energy products will take away no momentum, so
(3)
Setting (2) equal to (3), we find εγ = εmin.
(4)
So the threshold for this reaction
(5)
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