# I Which baryons can annihilate?

1. Jun 30, 2017

### snorkack

Different baryons routinely annihilate. Like antineutron and proton.
Wikipedia article on annihilation acknowledges this.
But at
https://en.wikipedia.org/wiki/Annihilation#Proton-antiproton_annihilation
near end of first section, I find statement:
The most common (lowest energy and longest lifetime) baryon that shares no flavour with nucleons is omega hyperon.
Annihilation of antiomega hyperon would be energetically favourable. 1672 MeV of Ω plus 938 MeV of proton sums up to 2610 MeV, while 3 kaons would be just about 1490 MeV.
So, does antiomega hyperon have a conspicuously lower annihilation cross-section and longer lifetime in matter compared to other antihyperons which do share quark flavours with nucleons?

2. Jun 30, 2017

### Staff: Mentor

$\Omega$ has a lifetime of 82 ps, corresponding to a few millimeters to centimeters of flight distance, and we cannot produce it at low energies (with relevant cross section). It decays before we could observe low-energetic annihilation reactions.