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RE: Composite particles: let’s play Lego! (Particle Physics Series – Episode 2)
This is a great post and one i enjoy seeing on steemit! Im just a little confused on the quantum chromodynamic principle. What do the actual terms of the colors have to do with the charge? Im having a hard time understanding the term ¨white". Im assuming it has something to do with the fact that matter would be ¨visible¨ as opposed to dark-mater?
Thank you for your question, and I truly appreciate you reading the post in depth :-).
You know the electric charge, right? 2 electrons, both with a negative charge will repel each other via the electromagnetic force. But 2 neutrons will not, because they have no electric charge. It is the charge that triggers the application of the electromagnetic force.
There are also 3 other forces known in nature: The gravitational force, the strong force (that binds nucleons and quarks together), and the weak force. Each of these forces have a specific ‘charge’ that is associated with them and that can trigger them.
For example, gravity: two objects will attract each other because of their mass. Bigger the mass, bigger the gravitational force between them, right? Well, here the ‘charge’ of the gravitational force is the mass. The mass triggers the force…
The strong force has also a ‘charge’ called ‘color’. A particle with color charge will trigger the strong force that will act on other particles with color charge. It is a charge much more complex than the electromagnetic charge (the electric charge) and the gravitational charge (mass), as it can come in many variations. Instead of having only 1 level for gravity , or 2 levels like the negative or positive electric charge, the color charge has many more levels. It can be green, blue or red for quarks, cyan (anti-red), yellow (anti-blue) and magenta (anti-green) for antiquarks.
The term “color” for the ‘strong force charge’ was chosen because the rules that define color addition in photography are mimicked by those of the strong charge in QCD. For a Hadron to exist, the sum of the colors of each of the quarks that compose it need to be white. For a Proton or a neutron, the three quarks have to be respectively red, blue and green. When you add in real life red, blue and green, you get white. Same for the mesons, which are also hadrons: they need to be white to exist. For example, a meson can be made a quark with a red color charge, and an antiquark with an anti-red color charge.
It is a weird concept, and can be a little un-intuitive at first, but it once you get it, it is limpid.
I hope this clarifies things for you a little, but if you remain still a little confused about the color charge, or wish to dig deeper, check this link: https://en.wikipedia.org/wiki/Color_charge
Be well and colorful!