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Parent questions:

What came first, neutrons or electrons?

Why saying that during electron capture the electron is converted to a neutrino?

Background: various nuclear phenomena show the transformation of a set of fundamental particles into others. In particular, an electron capture leads a proton plus an electron to a chain of events that result in a neutron and a neutrino. Or a proton produces a positron, a neutron, a neutrino, etc.

In their answer, The_Sympathizer says in the end hadrons are observed to be made of subparticles and neither of them is an electron, so this is proof the electron does not survive the process of electron capture (sorry if I don't use the right words).

Yet, during all of these nuclear reactions, there is conservation of a number of things, including energy, charge, and other things.

So if a particle in the standard model is defined through its properties (mass, charge, spin, etc) and if after a nuclear reaction, those properties are redistributed among the final products, why is it different to say that part of the initial particles are redistributed? Is it just that the relation is not bijective, i.e. that properties constitute a particle but particles are not a set of properties?

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    $\begingroup$ "Those properties are redistributed among the final products." They aren't though- not all properties are conserved. Particle number, strangeness, weak isospin, and lepton family number, just to name a few. $\endgroup$
    – Chris ♦
    Commented May 11, 2019 at 23:44
  • $\begingroup$ And they cannot be computed from others? They are orthogonal dimensions, so to speak? $\endgroup$
    – Winston
    Commented May 11, 2019 at 23:49
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    $\begingroup$ No, they cannot be computed from others. $\endgroup$
    – Chris ♦
    Commented May 11, 2019 at 23:54
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    $\begingroup$ @Chris : However, one wouldn't necessarily expect all properties one could think of, to be conserved: e.g. particle number - if you can convert particles then having more or less of them afterward seems sensible - but this doesn't necessarily mean that the core idea here is wrong. In particular, it is not "is every conceivable property conserved" but rather, "can we describe each fundamental particle uniquely in terms of variable amounts of some set number of conserved properties?" $\endgroup$
    – The_Sympathizer
    Commented May 12, 2019 at 0:57
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    $\begingroup$ It's (probably) more accurate to say that those properties are properties of the various fields; a particle is "just" a quantized excitation of a field. $\endgroup$
    – PM 2Ring
    Commented May 13, 2019 at 4:00

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So if a particle in the standard model is defined through its properties (mass, charge, spin, etc)

It is defined as in the table of elementary partices, and its interactions are defined, i.e. what happens when interacting with another elementary particle by the forces defined between particles, with various coupling strengths ( this is quantum mechanics, not classical mechanics) all defined by modeling observations with the mathematics of quantum mechanics, in particular quantum field theory (example: quantum electrodynamics is one).

and if after a nuclear reaction,

Nuclei are composites of elementary particles

those properties are redistributed among the final products,

They are not redistributed, they follow the rules of the fundamental interactions, and the conservation laws, new particles may appear due to exchanges of quantum numbers. It is only the energy that is redistributed, and energy does not carry a particular particle label. It is the quantum number transfers or changes according to the interactions that will determine the new particle content.

why is it different to say that part of the initial particles are redistributed? Is it just that the relation is not bijective, i.e. that properties constitute a particle but particles are not a set of properties?

The identity of an elementary particle is defined by the quantum numbers in the table and the mass. Thats all. Quantum numbers are reshuffled according to the rules, but there is no identity in the energy packets outside of that. If the rules are obeyed it has a probability to happen. The energy packet does not have a DNA carrying the originating particle identity, other than connection through quantum number conservation.

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    $\begingroup$ So basically, you are answering by the negative to the main question, right? i.e. that particles are no more than their properties. $\endgroup$
    – Winston
    Commented May 12, 2019 at 6:18

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