# Tag Info

1

The answer is no, confinement does not logically imply indivisibility. There are models of particle physics -- generally known as preon models -- in which quarks are composite.

2

Here is a review from the particle data group of searches for compositeness for quarks and leptons. . It is from 2001 but I suppose that they are not updating it since it gives the basic parameters for their table of limits for quark and lepton compositeness (2015). In the review the word "confinement" does not appear, as it necessarily would have, if ...

0

He's relying on isospin symmetry. The integrals you exhibit are for the proton, but the the form factors in the ratio are proton in the denominator and neutron in the numerator. The claim is that the up-distribution of the proton is a good proxy for the down-distribution of the neutron and vice versa, and that the sea distributions are identical. That ...

2

Here is one way to think about it... Anything made of quarks must have net color neutrality. Quarks come in the following 'colors', RED, BLUE, and GREEN and all three combine to be color neutral Antiquarks come in the following 'colors', ANTIRED, ANTIBLUE, and ANTIGREEN and all three combine to be color neutral Colors and their anticolors combine to ...

9

Briefly, a hadron has to be color singlet ${\bf 1}$ under the $SU(3)_C$ color gauge group, due to color confinement. Examples: A single quark $q$ transforms in the fundamental representation ${\bf 3}$ of $SU(3)_C$, and is hence not allowed. See also related Phys.SE post here. A diquark $qq$ belongs to the tensor representation \${\bf 3}^{\otimes 2}:={\bf ...

22

This is covered by a few existing answers (see for example About free quarks and confinement) though surprisingly it doesn't appear that anyone has asked this exact question before. Anyhow, the answer is that the colour force is mediated by particles called gluons just as the electromagnetic force is mediated by photons. The difference is that while photons ...

8

Force is a classical concept. Even classically not all forces decrease with distance, as the forces acting on a spring show, which increase with distance. I do not see the connection with the three dimensions of space and the functional form of the potential of a force. The strong force is modeled with the exchange of gluons which are depicted in Feynman ...

0

Indeed protons and neutrons in the nucleus are very different than isolated. E.g. the neutron is assumed to be unstable isolated (~15mn lifetime) while they are say "stable" in the nucleus. But indeed in the nucleus protons and neutrons are quickly "blinking" all the time, exchanging genders as they exchange mesons (a pair quark-antiquark). So you might say ...

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