hw23 - d/dt For the inverse process (again assuming that e...

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Homework Set No. 3, Physics 880.08 Deadline – Monday, February 21, 2011 1. a. (15 pts) Calculate the diferential cross section dσ/dt For electron-positron annihi- lation into two photons, i.e., For e - + e + γ + γ. You may assume that electron and positron are massless. Express your answer in terms oF Mandelstam variables s , t and u , and electromagnetic coupling constant α EM . (Hint: you may want to use the replacement s λ = ± ǫ ( λ ) * μ ( k ) ǫ ( λ ) ν ( k ) → - g μν when summing over photon polarizations.) b. (10 pts) Calculate the diferential cross section
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Unformatted text preview: d/dt For the inverse process (again assuming that e + and e-are massless): + e-+ e + . Express your answer in terms oF Mandelstam variables s , t and u , and EM . Compare the answer with the result oF part a . Comment. 2. (25 pts) Problem 5.2 in Peskin and Schroeder. Clarication to their problem Formu-lation: you are asked to nd the diferential cross section in the center-oF-mass Frame. Also write an expression For d/dt . 1...
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