There are six types of quarks, known as flavors.
- Why where these types called flavors?
- Why do the flavors have such odd names (up, down, charm, strange, top, and bottom)?
[Physics] Why are quark types known as flavors
definitionparticle-physicsstandard-model
Related Solutions
The question: "I'm wondering if there is some good reason why the universe as we know it has to have twelve particles rather than just four."
The short answer: Our current standard description of the spin-1/2 property of the elementary particles is incomplete. A more complete theory would require that these particles arrive in 3 generations.
The medium answer: The spin-1/2 of the elementary fermions is an emergent property. The more fundamental spin property acts like position in that the Heisenberg uncertainty principle applies to consecutive measurements of the fundamental spin the same way the HUP applies to position measurements. This fundamental spin is invisible to us because it is renormalized away. What's left is three generations of the particle, each with the usual spin-1/2.
When a particle moves through positions it does so by way of an interaction between position and momentum. These are complementary variables. The equivalent concept for spin-1/2 is "Mutually unbiased bases" or MUBs. There are only (at most) three MUBs for spin-1/2. Letting a particle's spin move among them means that the number of degrees of freedom of the particle have tripled. So when you find the long time propagators over that Hopf algebra you end up with three times the usual number of particles. Hence there are three generations.
The long answer: The two (more or less classical) things we can theoretically measure for a spin-1/2 particle are its position and its spin. If we measure its spin, the spin is then forced into an eigenstate of spin so that measuring it again gives the same result. That is, a measurement of spin causes the spin to be determined. On the other hand, if we measure its position, then by the Heisenberg uncertainty principle, we will cause an unknown change to its momentum. The change in momentum makes it impossible for us to predict the result of a subsequent position measurement.
As quantum physicists, we long ago grew accustomed to this bizarre behavior. But imagine that nature is parsimonious with her underlying machinery. If so, we'd expect the fundamental (i.e. before renormalization) measurements of a spin-1/2 particle's position and spin to be similar. For such a theory to work, one must show that after renormalization, one obtains the usual spin-1/2.
A possible solution to this conundrum is given in the paper:
Found.Phys.40:1681-1699,(2010), Carl Brannen, Spin Path Integrals and Generations
http://arxiv.org/abs/1006.3114
The paper is a straightforward QFT resummation calculation. It assumes a strange (to us) spin-1/2 where measurements act like the not so strange position measurements. It resums the propagators for the theory and finds that the strange behavior disappears over long times. The long time propagators are equivalent to the usual spin-1/2. Furthermore, they appear in three generations. And it shows that the long time propagators have a form that matches the mysterious lepton mass formulas of Yoshio Koide.
Peer review: The paper was peer-reviewed through an arduous process of three reviewers. As with any journal article it had a managing editor, and a chief editor. Complaints about the physics have already been made by competent physicists who took the trouble of carefully reading the paper. It's unlikely that someone making a quick read of the paper is going to find something that hasn't already been argued through. The paper was selected by the chief editor of Found. Phys. as suitable for publication in that journal and so published last year.
The chief editor of Found. Phys. is now Gerard 't Hooft. His attitude on publishing junk is quite clear, he writes
How to become a bad theoretical physicist
On your way towards becoming a bad theoretician, take your own immature theory, stop checking it for mistakes, don't listen to colleagues who do spot weaknesses, and start admiring your own infallible intelligence. Try to overshout all your critics, and have your work published anyway. If the well-established science media refuse to publish your work, start your own publishing company and edit your own books. If you are really clever you can find yourself a formerly professional physics journal where the chief editor is asleep. http://www.phys.uu.nl/~thooft/theoristbad.html
One hopes that 't Hooft wasn't asleep when he allowed this paper to be published.
Extensions: My next paper on the subject extends the above calculation to obtain the weak hypercharge and weak isospin quantum numbers. It uses methods similar to the above, that is, the calculation of long time propagators, but uses a more sophisticated method of manipulating the Feynman diagrams called "Hopf algebra" or "quantum algebra". I'm figuring on sending it in to the same journal. It's close to getting finished, I basically need to reread it over and over and add references:
http://brannenworks.com/E8/HopfWeakQNs.pdf
The up/down top/bottom should be self evident: in a matrix representation the vector is written that way
+1/2>
-1/2>
So in the isotopic spin space (the SU(2) of the SU(2)xSU(3)xU(1) of the Standard Model) according to the charge the one on top was called the up and the one on bottom, the down.
The strange got its name from the strange mesons, which when discovered were behaving strangely, with respect to pions, needing a new quantum number because they were generated in pairs ( Lamda K) and the quantum number became the "strange" one.
Charm was a whim as , they were charmed by its existence since it had been predicted to exist given the quark model expectations; from the quark entry in wikipedia:
Glashow, who coproposed charm quark with Bjorken, is quoted as saying, "We called our construct the 'charmed quark', for we were fascinated and pleased by the symmetry it brought to the subnuclear world
Top and Bottom, again because of the position in the vector, and Beauty instead of Bottom out of whimsy again, keeping the B, and Truth keeping the T.
Who said that physicists are not having fun?
For completeness, the name "quark" has the origin in Finnegan's Wake of James Joyce:
For some time, Gell-Mann was undecided on an actual spelling for the term he intended to coin, until he found the word quark in James Joyce's book Finnegans Wake:
Three quarks for Muster Mark!
Of course our Germanic language friends say that Quark is a type of cheese!
Actually the quark article in wikipedia has an etymology section for the quarks, to be read for completeness.
Best Answer
It is important to remember that words like this get used in spit-balling sessions and then stick. You have to think of a couple of guy sitting by a black board, coffee in hand saying something like
It's just a word made up on the spot.
That said, I think that "up" and "down" came from an analogy with spin. "Strange" interaction were so called because they violated rules of thumb for other known interactions...
After that things got out of hand.
Side note: "flavor" is also used to distinguish the generation of leptons (and will no doubt be applied to any sterile neutrinos that make an appearance).
Side note$^2$: For a long time there were competing names for the third generation flavors. I'm a little sad that "top" and "bottom" won out against "truth" and "beauty".