Scientists who work at IceCube Neutrino Observatory, an instrument submerged deep within the ice of Antarctica that detects particles that come from cosmic events, reported that they have come up empty in their search for the mysterious particle called sterile neutrino.
After diligently searching for the hypothetical subatomic particle, researchers working at the particle detector said that they are now nearly certain that this particle does not exist and will not be added in the members of the family of neutrinos that are already accepted as part of the Standard Model of particle physics.
Neutrinos are nearly massless ghost particles that rarely interact with matter. Scientists detected the three known flavors of neutrinos, the muon, electron and tau, because they are charged with weak nuclear interaction.
Earlier experiments hinted that a fourth flavor of neutrino may exist. Unlike other neutrinos that rarely interact with matter, the hypothetical sterile neutrino is believed not to interact with matter at all. Sterile neutrino is also a potential candidate for dark matter that comprises more than a quarter of the universe's mass.
"One or more types of sterile neutrinos could help solve a number of mysteries, such as why there is more matter than antimatter in the universe," said Jason Koskinen, from the University of Copenhagen.
Koskinen added that the sterile neutrino may help explain the imbalance that cannot be explained by the three other neutrinos.
"A sterile neutrino with gravity could also shed light on the mysterious dark matter."
To confirm the existence of a sterile neutrino, researchers have to catch it in the process of transforming into one of the three flavors, a process called neutrino oscillation.
It was theorized that the sterile neutrino with mass of about 1 eV could form during quantum fluctuations that constantly cause the particles to transform between being one of the three neutrino flavors. If there was a fourth option for conversion, this should be detected in the IceCube detector regardless if the sterile neutrinos are not directly detected.
Unfortunately, as reported in the journal Physical Review Letters on Aug. 8, scientists did not find a trace of the particle.
"No evidence for anomalous νμ or ν¯μ disappearance is observed in either of two independently developed analyses, each using one year of atmospheric neutrino data," the researchers reported.
"New exclusion limits are placed on the parameter space of the 3 + 1 model, in which muon antineutrinos experience a strong Mikheyev-Smirnov-Wolfenstein-resonant oscillation."
Despite not finding evidence of sterile neutrinos, researchers said that their existence should not yet be ruled out completely.