Another q on electron positron collisons

[lark]

Another q on electron positron collisons :)

I asked earlier about why spin-0 bottomonium mesons aren't created directly with electron positron collisions.
So I found out that when an electron and positron collides, it may make a virtual photon, and the virtual photon turns into a spin-1 bottomonium meson.
Trying to understand this, here's my guesses:

Although a virtual particle can borrow energy and thus temporarily violate energy conservation, virtual particle creation & destruction has to obey spin conservation. So a virtual photon can only be converted into something with spin 1.
And when the electron and positron collide, they'd have to have spin in the same direction, in order to annihilate into a virtual photon. Otherwise something else would happen.
I noticed that if the electron and positron have spin in opposite directions, their magnetic moments would be in the same direction so there'd be a repulsion. I don't know if this is a significant effect here?
So when you're trying to produce bottomonium mesons, would you try to make sure that the electron and positron have spin in the same direction?
Laura

 

[LightHero]

Yes, it is important to make sure that the electron and positron have the same spin direction when attempting to create bottomonium mesons. This ensures that the spins of the electron and positron can combine to form a virtual photon with spin 1, which can then decay into the bottomonium meson. If the electron and positron have opposite spin directions, they will not be able to combine to form a virtual photon, and thus no bottomonium meson will be produced. Additionally, having the electron and positron with opposite spins will cause a repulsive force between them, making it more difficult for them to interact and produce the desired bottomonium meson.

 

[sir-pinski]

Hi Laura,

Thank you for following up on your previous question about electron positron collisions and bottomonium mesons. Your guesses are on the right track. When an electron and positron collide, they can create a virtual photon, which can then turn into a spin-1 bottomonium meson. This is because of the conservation of spin in the creation and destruction of virtual particles.

In terms of the spin direction of the electron and positron, it is true that their spins need to be parallel in order for them to annihilate into a virtual photon. This is because the spin of the virtual photon must be the sum of the spins of the electron and positron. If their spins are not aligned, then they will not annihilate and something else will happen.

As for the repulsive effect of opposite spin directions, this is not a significant factor in the creation of bottomonium mesons. The main factor is the conservation of spin and the creation of a virtual photon.

To produce bottomonium mesons, researchers do indeed try to ensure that the electron and positron have the same spin direction. This can be achieved through various methods, such as using polarized beams or selecting only certain spin states of the electron and positron.

I hope this helps clarify things for you. Keep on learning and asking questions!