The average lifetime would always be greater than the half-life, because a few long lived particles will stick around a while, pushing up the average.
At the LHC, each individual collision occurs over a tiny fraction of a second, but the experiments can take months to collect enough data.
The thing about half life, that the way I’m understanding it, may imply that there are stray Higgs Bosons or Strange/Charmed Quarks here and there that could stick around unreasonably long, maybe, for minutes or hours… is that even possible?
that could stick around unreasonably long, maybe, for minutes or hours… is that even possible?
Possible, yes, probable, no.
Suppose we have a particle with a half-life of one second. To have decent odds of one sticking around for n seconds, you’d need to observe around 2^n particles. For 10 seconds, that’s 1024 particles. For 20 seconds, that’s around million particles, 30 seconds, ~1 billion particles. To see a particle last for one minute, you’d have to observe ~1,000,000,000,000,000,000 particles.
Particles observed at the LHC typically have half-lives of much less than one second.
Half-life is time for half the material to decay. This is repeated at every step, so to reach 1/8 of the original amount takes 3 times the half-life.
https://en.m.wikipedia.org/wiki/Half-life
Particle decay tends to be Mean Lifetime. https://en.m.wikipedia.org/wiki/Particle_decay
High energy things decay really fast.
“Average” is ambiguous—it could mean arithmetic mean, geometric mean, median, mode, etc.
The half-life is equivalent to the median lifetime, but the name is more self-explanatory (and emphasizes that half the radiation is still there).