Hello, I'm new to this forum. I was hoping someone might be able to help me understand what the constituents of a neutron are. Last month I read a book that stated that the neutron was composed of 2 'd quarks' and 1 'u quark'... while the proton is composed of 2 'u quarks' and 1 'd quark'. The 'd quarks' are slightly more massive than the 'u quark'.... giving the neutron the .138 extra mass (compared to the proton). The book I'm currently reading states that the neutron is composed of (1proton + 1electron + 1neutrino).... and that this accounts for the larger mass of the neutron compared to the proton. Are these 2 descriptions basically saying the same thing, but from different perspectives? Or is one description right while the other is wrong? Thanks for any help.