3. (i) Describe the helicity of neutrinos and antineutrinos in the Standard Model. Discuss how a nonzero neutrino mass w
Posted: Tue May 17, 2022 9:56 pm
3. (i) Describe the helicity of neutrinos and antineutrinos in the Standard Model. Discuss how a nonzero neutrino mass would affect their helicity. (ii) Consider the decay of a charged pion, it → u vya (a) Draw the Feynman diagram for this decay, labelling clearly all particles and vertex strengths. (b) In a separate drawing, indicate the spin and momentum vector directions for the outgoing ut and v, in the rest frame of the nt. (c) The decay involving muon flavoured leptons is the dominant decay mode of charged pions, with a branching ratio BR = 99.99%. Why is the alternate decay at netve heavily suppressed such that its branching ratio is BR = 1 x 10-4?