The Higgs Boson's Twin Could Reveal Our Universes Dark Sector

[Igel]

2. They're difficult to detect.

So they have large detectors that work 24/7 to find them.

And they're incredibly abundant.

From www.sns.ias.edu/~jnb/Papers/Popular/Scientificamerican69/scientificamerican69.html :
"The flux of solar neutrinos at the earth's surface is on the order of 10^11 per square centimeter per second"

Yeah, that means every cm of ground facing the Sun is receiving 100,000,000,000 neutrinos per second.

The LHC produces nowhere near that many particles per year.

I suspect that they just know they're dumping in a lot of energy, a lot of momentum, and don't monitor each and every interaction. They found the Higgs not by watching momentum from when the Higgs was produced but by looking at Higgs decay products. If you have the entire event caught on film, then you check momentum.

https://arxiv.org/ftp/arxiv/papers/1703/1703.03952.pdf discusses Higgs production. I might understand bits if I took the time to puzzle over it for a while. Not gonna.