I was recently reading an article about a tetraquark combo TCC+ that was found and measured. The pic in the article looks wrong to me. It shows C antiU on top and a C antiD on the bottom. I know it is only an artist depiction, but to me it would make more sense to be C antiU on top and antiD C on the bottom. This way the antiquarks could bind with both C quarks..... Or do the quarks move continuously in a particle, swapping places?
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The rule of thumb is that a particle can be considered “localized” only if its “size” parameter is much smaller than its de Broglie wavelength $\lambda = h/p$. For example, in solid copper at room temperature, we can use the non-relativistic $$ E = \frac{p^2}{2m} \frac{c^2}{c^2} ≈ kT ≈ 25\rm\,meV $$ for both the lattice ions and the conduction electrons, for de Broglie wavelength $$ \lambda = \frac{hc}{\sqrt{2mc^2E}} =\frac{1200\rm\,eV\,nm}{\sqrt{mc^2\rm\ 50\,meV}} $$
For the lattice ions, with mass around 50 GeV, the wavelength works out to be much smaller than the typical interatomic distance of order 0.1 nm. But for the less massive electrons, their wavelength extends over many lattice spacings. This is why our useful mental picture of a metal has a “fixed” lattice bathed in an “ocean” of conduction electrons.
For electrons in an atom, nucleons in a nucleus, or quarks in a hadron, the wavelength is in each case comparable to the size of the confined system. In your double-charmed tetraquark, you cannot think of the heavy quarks being on “this side” and the light quarks on “that side.” Each of the quarks is spread over the whole volume of the hadron.
rob
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