How? Quarks can't change into leptons. Charged leptons can't change directly into other charged leptons. And neither charged leptons nor hadrons are going to

How? Quarks can't change into leptons. Charged leptons can't change directly into other charged leptons. And neither charged leptons nor hadrons are going to pass through such a quantity of matter, as you say. I mean I assume other cases are technically possible but they don't seem very likely...