Dark matter: Out with the WIMPs, in with the SIMPs?

CrazyNeutrino said:

Dark matter: Out with the WIMPs, in with the SIMPs?

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Dark matter: Out with the WIMPs, in with the SIMPs?

Like cops tracking the wrong person, physicists seeking to identify dark matter—the mysterious stuff whose gravity appears to bind the galaxies—may have been stalking the wrong particle. In fact, a particle with some properties opposite to those of physicists’ current favorite dark matter candidate—the weakly interacting massive particle, or WIMP—would do just as good a job at explaining the stuff, a quartet of theorists says. Hypothetical strongly interacting massive particles—or SIMPs—would also better account for some astrophysical observations, they argue.

“We’ve been searching for WIMPs for quite some time, but we haven’t found them yet, so I think it’s important to think outside the box,” says Yonit Hochberg, a theorist at Lawrence Berkeley National Laboratory and the University of California (UC), Berkeley, and an author of the new paper.

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> However, Hochberg and colleagues argue that dark matter could also consist of lighter particles that have a mass somewhere around one-tenth that of the proton and interact with one another—but not ordinary matter—very strongly.

This looks a bit like a revival of the old Axion model for dark matter. The Axion has an even smaller mass than that, about a millionth of the mass of an electron. They haven’t been found either, despite extensive searches such as for Axions coming from the Sun.

The main reason that particles about one-tenth the mass of a proton have been rejected as possible dark matter is that because they haven’t been found. Wouldn’t they have been found ages ago at the times that the muon and pion were found? A proton has a mass of approximately 938 MeV/c, a muon 106 MeV/c, a pion 139 MeV/c. Muon detection is big business in the subatomic particle world.

Another problem with strongly interacting particles is that they give off gamma rays when interacting with one another then those would have been seen.