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Asked by anon-351151 on 6 Mar 2023.
Question: Where did the name ‘beauty quark’ come from? What sets it apart from other fundamental particles?
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Mary Richardson-Slipper answered on 6 Mar 2023:
So in the Standard Model of Particle Physics, we have 6 quarks. We group them into three pairs we call ‘generations’. In each pairing, there is a positively charged quark with a charge of +2/3, and a negatively charged quark with charge -1/3. We have ‘up’ and ‘down’, ‘charm’ and ‘strange’, and the third generation ‘truth’ and ‘beauty’, or ‘top’ and ‘beauty’ or ‘top’ and ‘bottom’ (it depends who you ask on which name they use!).
There are a lot of theories about where they got their names. The strange quark was the first to be discovered because of some ‘strange behaviour’ – hence the name. I don’t know of the story behind the beauty quark, but I think whoever found them probably just needed another pair of words!
As for why beauty quarks are set apart from the others, the beauty quark is heavier than the up, down, strange and charm, but not as heavy as the top. We produce a lot of beauty quarks in collisions at the LHC and because they live a bit longer than the others, we can pick them out from the crowd. Particles containing beauty quarks are great laboratories for studying phenomena such as CP violation which helps us understand the difference between matter and antimatter!
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Jonathan Edward Davies answered on 8 Mar 2023:
The “beauty” quark is sometimes also known as the “bottom” quark (to go with the “top” quark, which is occasionally known as the “truth” quark). I guess “beauty physics” just has a better ring than “bottom physics”! Top quarks are also good places to look to test our theory of particle physics but unfortunately they don’t stick around for very long and so don’t have time to group together with other quarks to make bigger particles (things like protons or neutrons). Since the “beauty” quark is the next heaviest then it can decay into all the other types of quark (not top) so we have the opportunity to study the physics of all of these particles for free.
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Joel Goldstein answered on 13 Mar 2023:
As far as I know (it is a bit before even my time….) the original names for the third-generation quarks were top and bottom (following the first-generation up and down). Hence they were abbreviated “t” and “b”. At some point someone suggested that it would be better if “t” and “b” stood for “truth” and “beauty”, possibly in an effort to be more poetic, possibly just as a bit of a joke.
It is interesting that “truth” never really caught on, and the t quark has almost always been referred to as the “top”. “Beauty” has had a bit more success, but most people I know still say “bottom quark”.
The things that really set apart bottom (and top) quarks are their mass (why are they so heavy?) and the fact that they are a third generation of matter particles (along with the tau lepton and its neutrino). Having a third generation (according to our current theories) is the only way to get any practical difference between matter and antimatter, which in turn means that the universe we see (dominated by matter) can exist.
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