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Unformatted text preview: 253a/Schwartz Due November 16, 2010 Problem Set 10 1. Particle decays. Recall that the decay rate is given by the general formula d = 1 2 E 1 |M| 2 d 3 p 2 (2 ) 3 1 2 E 2 d 3 p n (2 ) 3 1 2 E n (2 ) 4 4 ( p 1 p 2 p n ) (1) a) Evaluate the phase space integrals for 1 2 decays. Show that the total rate is: ( e + + e- ) = 1 4 x 2 16 m |M| 2 , x = m e m (2) b) Evaluate for a particle of mass m decaying to e + e- of mass m e if i. is a scalar , with interaction g S ii. is a a pseudoscalar , with interaction ig P 5 iii. is a vector , with interaction g V iv. is an axial vector , with interaction ig A 5 v. is an tensor , with interaction ig T c) The CDF collaboration may be seeing evidence of a new particle which decays only to leptons ( , and e ) whose mass is around 4 GeV. About 25% of the time it decays to + - . What spin and parity might this particle have? 2. The neutrino is a neutral particle like the electron. As we saw in the last problem set, its interactions violate parity: the left-handed neutrino couples to the...
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This note was uploaded on 02/04/2012 for the course PHYS 253A at Harvard.