# I Photoproduction of pions off protons

1. Nov 6, 2016

### SnoliF

A meson can be produced by a high energy photon scattering off a nucleon in an interaction such as
$$\gamma + p \rightarrow p + \pi^0$$
As long as the photon is sufficiently energetic, mesons heavier than the pion can be produced, as well as multiple mesons such as $\pi^{+} + \pi^{-}$ provided the net charge of the mesons is zero.

$$\gamma + p \rightarrow n + \pi^+$$
but I have a question that I haven't been able to find an answer for- In the second interaction what process allows a proton to be converted to a neutron?

2. Nov 6, 2016

### Staff: Mentor

In terms of the involved quarks, it is the same reaction (2*up, 1* down -> 2*up, 2*down, 1*anti-down), they just group differently into hadrons in the second reaction.

3. Nov 6, 2016

### SnoliF

Thanks, that explains it perfectly.