# Synopsis: Neutrino Probes of Long-Range Interactions

Researchers place new limits on hypothetical interactions between neutrinos and large electron populations on galactic scales.

Searches for new fundamental interactions tend to concentrate on subatomic scales. Some theories, however, predict new interactions that—like gravity—can involve large numbers of particles acting over astronomical distances. A study by Mauricio Bustamante of the Niels Bohr Institute in Denmark and Sanjib Kumar Agarwalla of the Institute of Physics in Bhubaneswar, India, analyzes data from the IceCube Neutrino Observatory at the South Pole. The researchers looked for changes in neutrino oscillation behavior caused by long-range interactions with, for example, the $1{0}^{57}$electrons in the Sun or the $1{0}^{67}$electrons distributed throughout our Galaxy. The researchers find no such signatures, which allows them to place new constraints on these types of interactions.

Certain theories beyond the standard model predict long-range interaction between neutrinos and electrons mediated by a hypothetical particle called the Z´ vector boson. This proposed interaction is expected to be weak, but a large population of electrons within the interaction range could exert a collective Z´ force that affects neutrino oscillations. Previous studies failed to find evidence of such an effect in solar, reactor, and atmospheric neutrino data, placing limits on the strength of the Z´ interaction over solar system scales.

Agarwalla and Bustamante investigated Z´ interactions using the highest-energy neutrinos observed by IceCube. These neutrinos are extragalactic in origin, which means they are sensitive to the collective effect of electrons in the Milky Way and beyond. Bustamante and Agarwalla modeled the cumulative influence from these electrons and determined how strong the Z´ interaction could be without contradicting the IceCube data. From this analysis, they were able to place the first upper limits on the Z´ interaction strength over Galactic and extragalactic scales.

This research is published in Physical Review Letters.

–Michael Schirber

Michael Schirber is a Corresponding Editor for Physics based in Lyon, France.

More Features »

### Announcements

More Announcements »

## Previous Synopsis

Atomic and Molecular Physics

## Next Synopsis

Biological Physics

## Related Articles

Astrophysics

### Synopsis: How Dark Matter Shaped the First Galaxies

Simulations show that competing models of dark matter produce primordial star-forming regions that look very different from one another. Read More »

Particles and Fields

### Synopsis: A New Plasma-Based Axion Detector

A proposed device could detect the hypothesized dark matter particle in a mass regime not probed by other devices. Read More »

Particles and Fields

### Focus: “Quantum Foam” Scrubs Away Gigantic Cosmic Energy

Theory suggests that empty space is filled with enormous energy, but according to a new proposal, this energy may be hidden because its effects cancel at the tiniest scales. Read More »