Hard physics homework problem?

Using the Lorentz transformations of momentum/energy of the 4-momentum along the x-direction, derive an expression for the laboratory angle of emission of a ɣ-ray by an unstable particle in terms of the angle of emission in the rest-frame of the particle. Thus show that for a beam of very high-energy particles,... show more Using the Lorentz transformations of momentum/energy of the 4-momentum along the x-direction, derive an expression for the laboratory angle of emission of a ɣ-ray by an unstable particle in terms of the angle of emission in the rest-frame of the particle. Thus show that for a beam of very high-energy particles, half the ɣ-rays will be concentrated inside a forward cone of opening angle theta of order 1/ɣ, with of course ɣ = 1 / sqrt(1-v^2/c^2).

Thanks!
3 answers 3