They would therefore not produce electrons when they interacted, and the detector would be blind to them (the neutrino energy is not high enough to produce the more massive muon or tau).
As best they can determine, the perturber is perhaps ten times more massive than Earth, or roughly half as massive as Neptune, and it is very distant indeed.
It is estimated to be 2326 ± in diameter, and 27% more massive than Pluto, or about 0.27% of the Earth's mass.
It also follows that one or more massive particles cannot decay into a single massless particle, conserving both energy and momentum.
In the blowout preventer, one or more massive rams mounted perpendicular to the flow can be activated, sealing the space between the drill pipe and the bore of the preventer, covering the opening if there is no drill pipe or even shearing the pipe if necessary.
Telescopes on the ground and NASA's prolific Kepler space telescope have detected many "super-Earths"—worlds just a few times larger or more massive than our own orbiting close to their parent stars.
Nineteen moons are known to be massive enough to have relaxed into a rounded shape under their own gravity, and seven of them are more massive than either Eris or Pluto.
There is no defined upper limit, and an object larger or more massive than Mercury that has not "cleared the neighbourhood around its orbit" would be classified as a dwarf planet.
"It would have locked in, for a generation or more, massive development of among the dirtiest fuels on the planet — posing a serious threat to our air, land water, and climate.
Perl suspected there was a third generation, or family, including a lepton far more massive than either the electron or its brother particle, the muon.
