ORCA uses neutrinos to test Lorentz invariance
· BehindLines newsroom
A detector beneath the Mediterranean is putting a principle of relativity to the test. A KM3NeT collaboration study listed in the November edition of the Journal of Cosmology and Astroparticle Physics searches atmospheric-neutrino data for departures from Lorentz invariance. The researchers find none within the framework examined.
A null result that narrows the possibilities
Lorentz invariance is one of the foundations of current theories of particles and gravity. Here, testing it means looking for possible changes in neutrino behaviour rather than photographing a distant object. The ORCA detector is part of the KM3NeT infrastructure; it turns light traces produced in water into information for analysis.
The work uses a partial configuration of six detection units. Observations collected from January 2020 to November 2021 amount to 510 live days, about 1.4 years, and 5,828 candidate events. Its performance therefore should not be attributed to the future full installation. The version deposited on arXiv in March also distinguishes the work’s initial circulation from its listing in the journal in November.
Examining a specific hypothesis
The authors look for a class of violations described as isotropic: the hypothesis being tested does not favour any particular direction. Finding no signal allows them to set limits on certain model parameters, complementing existing experimental constraints.
That does not demonstrate that every new theory is impossible or that every aspect of relativity has been verified without limits. The conclusion depends on the available data, their precision and the chosen assumptions. A more sensitive experiment could still explore effects too small for this analysis.
In particular, the study provides some of the first direct constraints on certain possible effects involving muon and tau neutrinos. The result clarifies the experiment’s reach without turning an absence of evidence into a universal certainty.