# Synopsis: Looking under the Antarctic ice for evidence of dark matter

Detectors buried beneath the Antarctic ice place stringent limits on the presence of dark matter particles, called neutralinos, in the sun.

In the search for dark matter, among the most interesting candidates is the neutralino, a neutral particle, predicted in supersymmetric extensions of the standard model, which interacts only weakly with other matter. Since the neutralino is expected to be stable, it may be possible to find particles that are relics of the early universe.

Theorists have predicted that the sun’s gravity can trap neutralinos, which could collect in its center and then annihilate each other. The standard-model particles created by these annihilations could subsequently decay, producing high-energy neutrinos that could escape from the sun and be detected on earth. Based on searches for these neutrinos, the IceCube Collaboration has now reported in Physical Review Letters new limits on neutralino annihilations in the sun.

The IceCube neutrino detector is located between $1.5$ and $2.5\phantom{\rule{0.333em}{0ex}}\text{km}$ beneath the Antarctic ice, to reduce background events from cosmic rays. When muon neutrinos from the sun interact with the ice, they create relativistic charged particles (muons and showers of hadrons) that produce Cherenkov light, which is picked up by the detector. In an experiment lasting more than three months, no excess of neutrinos from the direction of the sun was detected. The experimentalists have therefore placed stringent limits on neutralino annihilations in the sun—a factor of $6$ improvement over some previous limits—and from these, limits on the cross section for neutralino-proton interactions for neutralinos with masses above $250\phantom{\rule{0.333em}{0ex}}\text{GeV}$. These results narrow the possibilities for dark matter. – Stanley Brown

### Announcements

More Announcements »

Nanophysics

Graphene

## Related Articles

Quantum Physics

### Synopsis: Testing Quantum Physics with Neutrinos

An experiment similar to the Bell inequality test confirms that neutrino oscillation is a quantum physics effect that is incompatible with alternative classical models. Read More »

Nuclear Physics

### Viewpoint: Of Gluons and Fireflies

Improved models of gluon fluctuations within protons have been developed and applied to particle collision data, pointing to strong gluon fluctuations at high energies. Read More »

Cosmology

### Synopsis: A Relativistic View of a Clumpy Universe

Cosmologists have begun using fully relativistic models to understand the effects of inhomogeneous matter distribution on the evolution of the Universe. Read More »