Nuclear & Particle Physics - Weak Interaction

The particle decay must be a weak interaction because

A. the is a lepton
B. the has spin zero
C. no neutrino is produced in the decay
D. it does not conserve angular momentum
E. it does not conserve strangeness

(GR9277 #91)

Solution:

Weak interactions:

• affect all known fermions (leptons and quarks; spin is a half-integer) caused by the emission or absorption of W and Z bosons. 
• the only process in which a quark can change to another quark, or a lepton to another lepton (flavor changes).
• fails to conserve strangeness or parity. 
• interactions involving neutrinos are mediated by the weak interaction.

A and B FALSE.

• Weak interaction changes lepton to another lepton.
• If is a lepton should be lepton too.
• According to B, has spin zero, means is a boson and does not interact mediated by weak interaction.

C FALSE.

• The neutrino is a fermion and interact primarily through the weak force.

D FALSE.

• Conservation of angular momentum is an exact laws, or more precisely have never been shown to be violated

Answer: E