The Force of protons and quarks?

  • #1
Mikael17
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How much force will it required to pull a quark out of a proton, and how much for to pull a proton out of a atom ?
 
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  • #2
"Force" is not a meaningful concept here, we want to be considering the energy of the interaction, and the amount will depend on the specific interaction.

For producing an isolated proton from a bound nucleus, google for "Proton emission".

A single quark cannot be pulled out of a proton, google for "quark confinement" for details of why not and what happens if you try.
 
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  • #3
It's worth noting, to avoid confusion, that there is a "force" that is minus the derivative of potential energy with respect to distance (see further comments below). However, that is not the force the OP is asking about. The force that is minus the gradient of potential energy is the force between two nucleons as a function of distance, not the force necessary to pull one proton out of an atom. They're not the same.

Also, for cases like the one under discussion here, the "force" that is the gradient of potential energy between nucleons is not obtained from direct measurements. In fact, neither is the potential energy itself. The various such potential energies that appear in the literature, such as the Reid potential, are phenomenological theoretical models constructed to fit data on things like binding energy per nucleon and scattering amplitudes. (Note that none of the actual data is data on force--forces are not directly measured in this domain.) None of them should be viewed as "the" definitive potential energy.
 
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  • #4
Mikael17 said:
how much for to pull a proton out of a atom ?
This depends upon the atom. Some atoms spontaneously emit protons because they are unstable (in which case the answer is zero). Other atoms are bound far more tightly and take far more energy to split.

In general, the binding energy of the nucleus of the atom before it is split plus the energy added to the system to split it (if any) must equal at least the combined binding energy and kinetic energy of the end products.

Because what really matters is the energy of the initial state of the atom compared to the energy of the post-split products of the split atom, it isn't really natural to talk about the force necessary to split an atom.

Force is a push or a pull, and the displacement of an object due to the application of a force on it is work. The ability to do work is called energy. Force and energy have different units. The strength of a force alone won't tell you everything you need to answer the question.

As a rule of thumb, however, it usually takes much less energy to split an atom than it does to turn a proton into something other than a proton.
Mikael17 said:
How much force will it required to pull a quark out of a proton,
This can't be done in the simple literal way that your are talking about.

Due to a property known as "quark confinement", free quarks isolated from a hadron (i.e. a composite particle made up of quarks and/or gluons which are bound by the strong force that is carried by gluons) don't exist in nature (apart from (1) top quarks before they decay (about 99% of the time into bottom quarks and W bosons) after an average of about 5*10-25 seconds, and (2) in the context of quark gluon plasma (QGP) at ultrahigh energies for extremely short periods of time in very small amounts over the entire last 13+ billion years anywhere in the Universe).

In high energy physics interactions, protons can collide and produce other stuff made of quarks and gluons bound into hadrons (the new stuff can even have kinds of quarks other than the up and down valence quarks of a proton) and/or other fundamental particles.

Since this is a basic level post, I'll just post a comic that illustrates just how counterintuitive and weird this is relative to common intuition with a comic strip analogy:

1702515552144.png


Unlike atoms, which come in hundreds of varieties, all protons are identical. And, all protons are stable. Protons don't decay, and don't turn into anything else, unless there is an interaction with it.

In an interaction that transforms a proton into stuff other than a proton, the mass-energy of the proton (a little less than 1 GeV/c2) plus the mass-energy of whatever "collides" with it, plus the kinetic energy of the colliding particles, has to equal the mass-energy of the end products, plus their kinetic energy.

Once again, it isn't natural to talk about the force necessary to cause a change of a proton into something else. Energy, which has different units, is what matters.

The interaction also has to conserve other properties such as aggregate electromagnetic charge, the number of quarks minus anti-quarks, the number of leptons (i.e. electron-like particles and neutrino-like particles) minus anti-leptons, and the aggregate mass-energy of the system. There are also some other conserved quantities that are harder to explain in a simple way.

Protons are stable because there are no possible combinations of particles that conserve all of these quantities with less mass-energy than a proton.

Put another way, you always have to add energy to turn a proton into something other than a proton, and the amount of energy you add determines what the proton can turn into.
 
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  • #5
An off-topic digression not responsive to the original question has been removed from this thread
 

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