Which interactions proceed by which fundamental force?

[cp255]

I have been getting ready for my Intro to Modern Physics final. The professor likes to ask a lot of questions like

Which of the following neutron reactions proceeds via the electromagnetic force?

Or something like this...

I have been looking all over the internet and my textbook. All I can find is kind of vague guidelines for this. How would I go about figuring it out?

I think the answers are Weak, EM, Strong, Weak (Just not completely sure why).

 

[Orodruin]

I think the answers are Weak, EM, Strong, Weak (Just not completely sure why).

You say you are not sure why, but what do you think?

 

[cp255]

I think I might have figure it out.

a) The weak force is needed to produce nutrinos.
b) If there are photons this implies EM
c) Strong because of baryons.
d) Weak because of neutrinos.

 

[Orodruin]

a) The weak force is needed to produce nutrinos.

Correct. Neutrinos only interact through the weak interactions.

b) If there are photons this implies EM

What about $\pi^+ \to \mu^+ + \nu_\mu + \gamma$? This has photons, but also neutrinos.

c) Strong because of baryons.

What about $K^+ \to \pi^+ + \pi^0$ or $\Lambda \to p + \pi^-$?

d) Weak because of neutrinos.

Correct.

 

[vela]

I have been looking all over the internet and my textbook. All I can find is kind of vague guidelines for this. How would I go about figuring it out?

If you're familiar with Feynman diagrams, try drawing the ones that represent a particular decay.