What the quark? A journey into Hadrons.
Most everyone has heard of a proton before; positive charge, part of the atom, but few dive deep into what a proton truly is. What a proton, is made of. Quarks, emit strong nuclear forces and can only be found within Hadrons because of color confinement. Color confinement is when color changing particles cannot be isolated. Basically, quarks can't be seen under normal conditions or any temperature under 2 trillion kelvin. Quarks are also never alone and are viewed in pairs/triplets. As the distance between two quarks increases so does the force, at a certain point the metaphorical string attaching them snaps and from the energy forms a quark anti-quark pair.
Hadrons are a combination of quarks to form composite particles. For clarification, a Hadron can be classified into two categories. Baryon (3 quarks) or meson (1 quark, 1 anti-quark). Protons and neutrons fall into the baryon category and are the only stable hadrons. In this article proton quarks will be highlighted as they are the most familiar composite particle.
In 1964, two men by the names of Murray Gell-Mann and George Zweig proposed the quark model. Gell-Mann and Zweig noticed a powerful intereacting symmetry between particles and found that the best explanation for this phenomenon could only be that Hadrons are made up of smaller constituent particles. The theory is called Quantum Chromodynamics, but you can call it QCD for short. Gell-Mann came up with a strategy he called the eightway fold which is a mathematical uniformity to categorize Hadrons. So comes in the baryons and mesons. It wasn't until 1968 that quarks were discovered, although, by SLAC. Multiple electron-proton scattering experiments were performed and the scattering was identified as being caused by particles within the proton. After many tests in many different locations it was determined that quarks really do have charges of 1/3 and 2/3 and their existence was confirmed.
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There are 6 different flavours of quarks. Up (u), down (d), strange (s), charm (c), top (t), bottom (b). And those are "strange" names if you ask me. If you'd like an easy way to remember the basics of quarks and/or the names of them, I recommend Hank Green's song "Strange Charm: A Song about Quarks" which is linked at the bottom of this article. I find the Up and Top quarks to be most peculiarly fascinating. You see, the up and top quarks are exactly the same in almost every way, they have the same electrical charge, interactions, and spin. The only difference is the top quark is 75,000 times more massive. Which is a HUGE difference, but get this, they take up the same amount of space. MIND BLOWN. You can go ahead and read that over again if nesscessary. So as of now, the question scientists are asking is how can one be bigger, but not have more material to it? Perhaps it's the way it passes through things? Maybe the top quark is more massive from the outside but more hollow in the inside. We have plenty of theories. But as of now, we can't wait to find a conclusive answer. When you break it down, an atom is extremely tiny, a proton even smaller, and then you have the quark, and I just think it's so beautiful how something so incredibly little can be so incredibly substantial. All in all, quarks are a engaging discovery waiting to be understood and it's my generations time to find it. Clear skies my friends.
Links:
https://www.youtube.com/watch?v=U0kXkWXSXRA