What is the most precise data for neutron-antineutron production by one photon (hitting a target in the laboratory system)?
and/or
What is the most precise data for neutron-antineutron annihilation to two photons? Is this data available online?
Asked
Active
Viewed 645 times
1
-
Bearing in mind that the neutron is a composite of quarks and gluons the neutron-antineutron reaction is going to be exceedingly messy. The probability that it will produce just two photons is vanishingly small. I'm sure Anna posted experimental data on proton-antiproton products in an answer (and it was messy) but I can't find the question ... – John Rennie Mar 22 '14 at 11:26
-
Aha! This is the answer I was thinking of. – John Rennie Mar 22 '14 at 11:29
1 Answers
1
There is no process $ \gamma \to n $ at all, nor $ \gamma \to n \bar{n}$ with an on-shell photon. The first violated multiple quantum number conservation rules and the second conservation of four-momentum.
The two-photon process
$$ \gamma + \gamma \to n + \bar{n} \,,$$
has allowed quantum numbers but will be exceedingly rare.
It is worth noting that photons do no "annihilate" in the usual sense, and two photon processes imply multiple interaction vertexes.
-
I know but that was not my question. Sorry for the misleading formulation. – ClassicalPhysicist Mar 21 '14 at 20:41