antimatter - How to create antineutrons?

Creating a beam of antiprotons allows to create antineutrons by charge exchange. How does this exchange work? The question pops up after the question "Is there a strong evidence of antineutron existance?"

Answer

There are lots of possibilities, depending on the energy of the antiproton beam. The hadron spectrum is quite complicated.

Probably the most likely channel is pion production: $$ \bar p \to \bar n + \pi^-. $$ This reaction requires a "spectator" nucleus to exchange energy and momentum with the $\bar p$, and so might be more properly written as $$ A + \bar p \to A^* + \bar n + \pi^- $$ where by $A^*$ I mean that the spectator nucleus might also end up in an excited state. The negative pions will eventually either decay (mostly $\pi^-\to\mu^-+\bar\nu_\mu$) or be captured on another nucleus in a reaction like $$ \pi^- + p \to n. $$ That's not the only available channel: with a spectator nucleus, you can make other antibaryons and mesons, for instance \begin{align} \bar p &\to \bar\Delta + \pi && \text{(which could make $\pi^\pm$ or $\pi^0$)} \\ \bar p &\to \bar\Lambda + K^- \\ \bar p &\to \bar\Sigma + K && \text{(could be a $K^0$ or a $K^-$)} \\ &\vdots \end{align}

Here's a review of low-energy nucleon-antinucleon interactions, which I haven't yet read.