[Physicist]

Yes but if these particles are only a couple of orders of magnitude down from a proton in terms of mass, the energy needed to create matter/anti-matter pairs would be much greater then that needed to create matter/anti-matter pairs of electrons.

That's true, but we can see evidence of distant anti-muon production and even anti-proton production, so such energies are available. (The mass of a muon is of the same order of magnitude as this supposed dark matter particle.)

OTOH, if instead dark matter is commonly distributed with anti-dark matter, the annhiliations that would be regularly produced should be easily observable.

That depends on how strongly coupled it is to electromagnetic particles like electrons. If the coupling is small enough, there could be a fantastic holocaust of annihilation occurring all about you--even through you--and you'd never know it.

[VadeRetro]

These things are at once fairly massive and yet we are to believe that experiments have been making them for some time. Even if they don't bang into other particles very readily, wouldn't the mass/energy disappearing into the production of these things have been noticed by now?

As I recall, the neutrino was noticed precisely because the energies of neutron decay didn't consistently add up. It became clear that something else was being produced, something that was carrying away some of the energy, even if we couldn't see it directly. Shouldn't something like that have happened already for the dark energy particle?

[swilhelm73]

That's true, but we can see evidence of distant anti-muon production and even anti-proton production, so such energies are available. (The mass of a muon is of the same order of magnitude as this supposed dark matter particle.

Do we know what natural processes would create proton/anti-proton pairs? Or the same for muons? I know there are several that can lead to electron/positron pairs...but I don't remember running across the other two - or have we observed the particles without discovering the process creating them?

That depends on how strongly coupled it is to electromagnetic particles like electrons. If the coupling is small enough, there could be a fantastic holocaust of annihilation occurring all about you--even through you--and you'd never know it.

Well, wouldn't the enery released be about;

energy = 4*10^-28 kg * (3*10^8 m/s)^2

energy = 3.6*10^-11 J per annihilation pair.

Wouldn't that be enough to show up in any number of experiments as extraneously produced energy?