What's keeping the last down quark in the proton from decaying
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What's keeping the last down quark in the proton from decaying in the same way the down quark in the neutron decays?
I imagine it might have something to do with Pauli since you'll have three up quarks with only 2 possible spin values but shouldn't the existance of color make this a non issue? They obviously all have different color.
A baryon with composition (uuu) is called [math]\Delta^{++}[/math], and it has a mass 30% higher than the proton. Hence going from proton to delta++ costs a lot of energy.
[math]\Delta^{++}[/math] commonly decays into a proton and pion though.
https://en.wikipedia.org/wiki/Delta_baryon
>>8119686
[math]\Delta^{++}[/math] also has [math]J=3/2[/math]. Is it not possible for a [math]J=1/2[/math] (uuu) state to exist, which would be lighter?
>>8119700
Considering just the spin, a 1/2 and 3/2 state are possible, but when adding in the orbital angular momentum, there's no way to maintain that 1/2 state. I don't feel like doing the math right now.
No, the lighter state does not exist.
I did a quick calculation and found that with the amount of energy it would take to convert a mole of protons to delta++'s, you could get 37,000 kg of matter to escape velocity on earth.
You need an accelerator to make these particles.
>>8119674
Why is the anti electron neutrino travelling backwards in time?
>>8119762
Feynman diagram =/= picture
>>8119762
It's not, but in these diagrams every anti-particle is depicted that way. If you just let the direction of the arrow tell you whether or not something is an anti-particle you can rotate each seperate piece of the diagram containing 3 lines that join up and the result will still make sense.
Example: pic shows the annihilation of a positron and an electron, but if you think away the plus and minus, rotate the entire thing by 45 degrees and just look at the direction of the arrows it will be a scattering of an electron and positron. The photon in the middle mediates the interaction between the two during the scattering.
>>8119787
>>8119806
I think his point was that if it's already labeled as an antineutrino, it shouldn't be shown propagating backwards. A neutrino propagating backwards is an antineutrino, so technically the diagram doesn't follow convention.
Anyone who understands Feynman diagrams knows this though so it's innocent.
God
>>8119856