What Fundamental Interactions Govern These Elementary Particle Processes?

[sudipmaity]

Homework Statement

Indicate the fundamental interactions through which the following processes occur.Justify.
n -> p+ e^- + ^-ν_e...1
p+p -> p+p+n+^-n...2
π⁺ -> μ⁺+ ^-ν_μ...3
γ -> e⁺ + e^-...4

Homework Equations

The Attempt at a Solution

1... is possible due to weak decay .electron antineutrino production.
2... is possible due to baryon no. conservation.
3... is not possible as lepton no. is not conserved.
4...is possible due to pair production and if energy of gamma rays is greater than 1.02MeV.It has been expermentally proven.
Are my deductions correct?? I am a particle, nuclear physics beginner.[/B]

 

[Orodruin]

Assuming that -ve means $\bar\nu_e$ etc. The first three are fine as long as the protons in (2) have enough CoM energy to create the neutron-antineutron pair.

For (4), it is not possible unless you can transfer momentum from an external field, such as that of a nearby nucleus. As it stands, you cannot conserve energy and momentum at the same time.

 

[vela]

1... is possible due to weak decay .electron antineutrino production.
2... is possible due to baryon no. conservation.
3... is not possible as lepton no. is not conserved.
4...is possible due to pair production and if energy of gamma rays is greater than 1.02MeV.It has been expermentally proven.
Are my deductions correct?? I am a particle, nuclear physics beginner.[/B]

You don't seem to be answering the question, which is to identify which interaction is responsible for each process.

For #2, I wouldn't say conservation of baryon number makes it possible. Conservation laws are generally used to rule out potential processes.

For #3, you need to recognize that the antineutrino has a lepton number of -1 because it's antimatter.

For #4, you need a second photon to be able to conserve momentum and energy. This second photon could be a virtual photon associated with the external field Orodruin mentions.

 

[sudipmaity]

Thank you vela.Is my answer to to #1 correct??

 

[vela]

You tell me. Why do you think it's mediated by the weak interaction?