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QCD -- made by idiot physicists

Anonymous Mon 08 Mar 06:34:07 2021 No.12805476 View Reply Original Report

Quoted By: >>12805487

>The idiot physicists, unable to come up with any wonderful Greek words anymore, call
this type of polarization by the unfortunate name of ’color’, which has nothing to do
with color in the normal sense.
--Feynman, Richard (1985), QED: The Strange Theory of Light and Matter.

Can /sci/ do better in naming the charge of QCD?

Anonymous

Anonymous Mon 08 Mar 2021 06:34:23 No.12805478 Report

Quoted By: >>12805497

Here's the background: in QED, there is one charge, which we're all familiar with, the electric charge. Mathematically we can call the charge C, such that using + to denote its regular charge and - to denote its anticharge:
$C^+ + C^- = 0$
In other words, a charge added to its corresponding anticharge yields 0 charge, or neutral. Compactly, we just call these charges $+$ and $-$ . Moving on to QCD, we have three charges which function in the following way:
$\begin{align} C_1^+ + C_1^- &= 0 \\ C_2^+ + C_2^- &= 0 \\ C_3^+ + C_3^- &= 0 \\ C_1^+ + C_2^+ + C_3^+ &= 0 \\ C_1^- + C_2^- + C_3^- &= 0 \end{align} $
Where the first three equations represent simple mesons, which follow the rules we expect: charge plus anticharge equals neutral. The last two equations represent baryons, with the first representing real baryons and the second being anti-baryons. Now three "positive" charges yield a neutral charge.

Feynman called these physicists idiots for calling it color. What say you, /sci/? Any better names?

Anonymous

Anonymous Mon 08 Mar 2021 06:39:25 No.12805487 Report

Quoted By:

>>12805476
“color” is actually a great name. the fact that “white” and “anti-white” and “colorless” all mesh with this idea is very clever. Murray Gell-Mann was a very thoughtful guy

Anonymous

Anonymous Mon 08 Mar 2021 06:49:21 No.12805497 Report

Quoted By:

>>12805478
tripolar dynamics

Anonymous

Anonymous Mon 08 Mar 2021 06:51:00 No.12805499 Report

Quoted By: >>12807736 >>12807764

also, what's $C_1^+ + C_1^+ + C_1^+$ ?
does $C_1^+ + C_1^+ = C_1^-$ ?

Anonymous

Anonymous Mon 08 Mar 2021 18:43:48 No.12807525 Report

Quoted By:

bumps

Anonymous

Anonymous Mon 08 Mar 2021 19:27:48 No.12807736 Report

Quoted By:

>>12805499
>also, what's C+1+C+1+C+1C1++C1++C1+?
3C_1+
>does C+1+C+1=C?1C1++C1+=C1??
it's 2C_1+
color charge is additive, they don't cancel out. it's like electric charge: if you take 2 electrons, they have a total charge of -2e, not 0.
however qcd confinement forbids any non-color neutral observable state at low energies so you'll never be able to observe such a state in a particle. some experiments have high enough energies that they can produce deconfined quark-gluon plasmas, but afaik they are extremely short lived and we can only measure their properties through their hardonized decay products
this is why mesons are always 1 quark + 1 anti-quark (one colour + one anti-color) so that they remain color neutral, even though they can be electrically charged.

Anonymous

Anonymous Mon 08 Mar 2021 19:35:17 No.12807764 Report

Quoted By:

>>12805499
Neither of those configurations seem to exist in stable particles. Gluons are interesting in that they carry two color charges, in the possible forms of
$C_i^+C_j^-, \qquad i\neq j$
these gluons function as a way to change a particle's color charge.
Another type of gluon exists which has color charge
$C_i^+C_i^-$
but these gluons are degenerate with each other, that is there are three mathematical configurations of this, but only two gluons of this type.
You'll realize by the structure of gluons, that they can exchange color amongst themselves, and even more interesting, the second type of gluon can self-interact and exchange color with itself.
All this amounts to QCD being a non-Abelian theory.

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