How does a proton have a mass-energy of ~1GeV when its constituent quarks have orders of magnitude less?

Question

I'm doing a short particle physics course, and I just can't make this add up... I'm told that a proton is about 1GeV, and up & down quarks are ~0.005GeV, so I don't understand where the extra mass-energy in a proton comes from.

Answer 1

Best Answer - Chosen by Asker

In order to hold something together, a force must be attractive. An attractive potential has negative energy, so the binding energy does not increase the mass, it decreases it.

Up and down quarks have a calculated bare mass of ~5MeV. This is the mass, *at rest*, of an isolated quark (calculated because a quark cannot exist in isolation). The remaining mass comes from the fact that quarks are *not* at rest inside a proton - the 3 quarks that make up the proton, (and the virtual sea of quark-antiquark pairs that exist in the colour field there), are moving at relativistic speeds. And as we all know from special relativity, an object moving at speeds comparable to the speed of light increases in mass as m = m0/sqrt(1-v^2/c^2).

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Asker's Comment:

Many thanks for this, it thorougly answered my question!

Answer 2

because there are 3 quarks in the proton 2 have the same charge and 1 has different.
There is a muclear force which is binding the quarks together.
I think....lol
good luck and Peace.

Answer 3

imagine a busy city centre at rush hour. a drunk physics professor stumbles out of a bar at 12 noon and bangs into 10 random people as they rush to the deli for a bacon sandwhich for lunch. the drunk professor will loose energy but gain momentum from the people he bangs into. they will loose 1/10 energy equal to his mass.

Answer 4

binding energy in the strong nuclear force between them

Answer 5

Strong nuclear force binding energy

Protons can also be accelerated, adding kinetic energy to their rest energy.

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