en.wikipedia.org/wiki/Neutrino
2 corrections found
the currently running MiniBooNE experiment suggested that sterile neutrinos are not required to explain the experimental data
This mixes up MiniBooNE and MicroBooNE. MiniBooNE is not currently running, and Fermilab later reported the 'no hint of a sterile neutrino' result from MicroBooNE, not MiniBooNE.
Full reasoning
This sentence is incorrect in two ways.
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MiniBooNE is not 'currently running.' Fermilab’s experiment-status page lists E-898/944 (MiniBooNE) as “Analysing Data,” not running. By contrast, Fermilab described MicroBooNE as the experiment that was currently operating.
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The 'sterile neutrinos are not required' result was not a current MiniBooNE result. In 2018, Fermilab wrote that MiniBooNE’s new data made the anomaly stronger, not weaker: “the MiniBooNE signal has grown even stronger.” The later Fermilab result showing “no hint of a sterile neutrino” came from MicroBooNE in 2021.
So the article’s wording misattributes the later sterile-neutrino null result to the wrong experiment and wrongly describes MiniBooNE as still running.
3 sources
- List of Experiments | Program Planning
E-898/944(MiniBooNE) Analysing Data ... E-974 (MicroBooNE) Data Taking
- Big boost for Fermilab's short-baseline neutrino experiments
The new data shows that the MiniBooNE signal has grown even stronger. Significantly stronger... That is exciting and very good news for the MicroBooNE experiment currently operating at Fermilab.
- MicroBooNE experiment's first results show no hint of a sterile neutrino
Four complementary analyses by Fermilab's MicroBooNE show no signs of a theorized fourth kind of neutrino known as the sterile neutrino.
Therefore, to be consistent with not having been detected in Z boson decays, heavy sterile neutrinos would need to have a mass of at least 45.6 GeV.
This overstates the LEP/Z-boson constraint. Z-width measurements limit only neutrinos that couple to the weak force; sterile neutrinos, by definition, need not couple to the Z at all, so they do not need to be heavier than 45.6 GeV.
Full reasoning
The conclusion here does not follow for sterile neutrinos.
CERN’s LEP measurement of the Z boson width established that three neutrino types couple to the weak force. Fermilab’s neutrino explainer states that sterile neutrinos might interact only through gravity and notes that LEP measured only three neutrinos that couple to the weak force.
That means the LEP/Z-width result rules out an extra light active neutrino with ordinary weak coupling, but it does not imply that a sterile neutrino must be heavier than m_Z/2 ≈ 45.6 GeV to evade detection. In fact, Fermilab explicitly discusses ongoing searches for light sterile neutrinos at the electronvolt scale, which would be impossible if all sterile neutrinos had to be above 45.6 GeV.
So the article’s sentence incorrectly turns a constraint on weakly coupled (active) neutrinos into a blanket mass lower bound for sterile neutrinos.
3 sources
- The Z boson - CERN
In 1989, first physics results from the Large Electron-Positron collider at CERN measured the width of the Z boson and confirmed that there are only three neutrino types in Nature: electron, muon and tau.
- Sterile neutrinos | All Things Neutrino (Fermilab)
By measuring the decays of the Z boson, scientists were able to measure to a very high precision that only three neutrinos couple to the weak force... But there could be any number of extra 'sterile' neutrinos that LEP would be unable to see.
- Sterile neutrinos | All Things Neutrino (Fermilab)
While the short-baseline experiments look for light sterile neutrinos carrying a relatively small amount of energy-at the electronvolt scale-there could be different sterile neutrinos at different energies.