Is an electron more stable than a proton/neutron?

Question

Is an electron more stable than a proton/neutron under extreme temperature/pressure conditions, like several 100 millions K?

Answer 1

Is an electron more stable than a proton/neutron?

Yes. An electron has no internal structure, and is the lightest fundamental particle with a non-zero electric charge. Therefore it cannot spontaneously decay into a lighter particle without violating charge conservation. So any transformation of an electron must either involve adding a large amount of energy to it, or an interaction with another particle (e.g. electron capture or electron-positron annihilation).

Protons and neutrons, however, are made up of quarks. Outside of a nucleus, a free neutron spontaneously decays into a proton, an electron and a neutrino, with a half-life of about 14 minutes. A free proton does not spontaneously decay in a similar way (as far as we know) because its mass is slightly less than the mass of a neutron. However, both neutrons and protons inside unstable nuclei can spontaneously decay via beta decay.