Is a neutron the mixture of a proton and an electron?

Is a neutron a combination of a proton and an electron either by mass and/or charge?

• Are you asking this because a free neutron often decays to a proton, an electron, and an electron antineutrino? Commented Oct 7, 2023 at 1:45
• Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
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Commented Oct 7, 2023 at 2:42
• Decay products can be created at the time of decay. They are not necessarily inside before the decay. Scattering experiments do not find protons or electrons inside neutrons. Commented Oct 7, 2023 at 5:22

Not in the sense you are probably thinking of - a neutron isn't a compound particle of a proton and electron. (That would be a Hydrogen atom.)

But there is a sense in which all the elementary particles are just different states of the same type of particle. There are a number of conserved quantities, called quantum numbers, that can jump from one particle to another in collisions, but are otherwise fixed and unchanging. One of these is the familiar electric charge, but there is another less familiar one called 'weak isospin'. It is called that because mathematically it acts a bit like the particle is spinning in a particular direction, and can flip its axis to spin the other way, but it isn't spinning about any ordinary spatial axis, but some 'internal' direction.

The difference between an up quark and down quark is their electric charge and weak isospin, which both differ by 1 unit. ('Up' has charge 2/3 and weak isospin +1/2, 'down' has charge -1/3 and weak isospin -1/2.) A neutron is an 'up' and two 'down's. A proton is two 'up's and a 'down'. So the decay of the neutron is where one on the 'down's flips, and becomes an 'up'.

At the same time, the difference between an electron and a neutrino is again electric charge and weak isospin, which again both differ by one unit. (Electrons have charge -1 and weak isospin -1/2, a neutrino has electric charge 0 and weak isospin +1/2. So a neutrino can turn into an electron if we do the same sort of flip on it as the one that turns a neutron into a proton.

We can't just flip particles on their own. Every action has to have an equal and opposite reaction, the force flipping one particle has to come from something else, which is affected oppositely. But we can do both at once - the neutron turns into a proton, and transfers charge and weak isospin to a neutrino, which turns it into an electron. (Or equivalently, the transferred charge turns into an anti-neutrino and electron pair.) The particle carrying this force in this particular case is called the W$$^-$$, and the force is called the weak nuclear force.

Thus, the properties that distinguish neutrons, protons, and electrons (electric charge and weak isospin), making them the particles they are, are in a sense sitting inside the neutron, and able to leave. However, it is not so much a particular type of matter so much as a particular type of motion of matter.

It is the same sort of thing as when we topple the first of line of dominos, and see the wave progress down the line, or when we drop a pebble into a pond covered with floating flower petals, and see the wave move across the pond without disturbing the petals. Nothing material is being transported, only a sort of motion. The conservation laws make it look like there is some 'stuff' moving around that has its own identity over time. Whether you can legitimately consider it such is more a matter for philosophy.

It was proposed that the neutron is proton with a cloud of some negative particle surrounding,

You could have thought of that particle as electron but due to its low mass (0.51 MeV) it wouldn't be possible to confine it in that tight space without a lot of energy.

It was proposed that the negative cloud be of pion (π⁻) as they were in fashion before the quarks and gluons.

Currently they are thought to be made up of quarks, as the scattering experiments indicates that they must not be point particles,

Whereas the deep inelastic scattering experiments suggest there must be some point particles inside it. 3 to be exact, but more energetic deep inelastic scattering experiments creates a soup of particles.

So, electron is just not enough massive to be confined around a proton to make a neutron.