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Old Aug 10th 2014, 09:44 PM   #11
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Originally Posted by topsquark View Post
We don't actually need to the electron to have neutrino pair production. It's just more likely if the electron is there because it explicitly carries the weak field. But the field is not necessary...pair production of any particle occurs whenever we "look" at a region of space very closely (ie. at the high energy scale.) The energy of the electron would certainly help the e- --> W- + (electron neutrino) interaction, but it is not actually necessary.

As to the electrons in heavy atoms, yes there might be more pair production of neutrinos, but there would also be a host of other "light" particles popping in and out as well...electron-positron and muon pair production would also be likely. The neutrinos would certainly be there but to produce them we need to produce a W, which makes e+ e- pair production much more likely.

-Dan
I'm not sure if I understand your reply completely. How does the e- --> W- + (electron neutrino) interaction relate to vacuum polarization by a charged particle such as the electron - leading to virtual particles getting produced and annihilating each other? What role does the electron play? It doesn't turn into virtual neutrinos (or other virtual particles), does it? However, it does seem to emit a W boson... Thanks for further clarification.

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Old Aug 11th 2014, 08:16 AM   #12
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Originally Posted by Curious View Post
I'm not sure if I understand your reply completely. How does the e- --> W- + (electron neutrino) interaction relate to vacuum polarization by a charged particle such as the electron - leading to virtual particles getting produced and annihilating each other? What role does the electron play? It doesn't turn into virtual neutrinos (or other virtual particles), does it? However, it does seem to emit a W boson... Thanks for further clarification.
Pair production in the vacuum doesn't need any particles close by to form them. Simply by looking that closely (which brings the problem into the high energy problem) we find the pair production. However this is much easier to do when we have a nearby particle that participates in the field. So your electron in an atom "emits" a weak nuclear force field which eases the difficulty of producing a pair. Another example might make it easier for you to see. Think of it this way: An electron "emits" an EM field because it is charged. Particles then can be affected by that field. It's the same way with the weak field.

In the interaction e --> W- + (electron neutrino) we do "lose" the electron. (However it is likely to come back quickly if we are doing this with an electron in an atom. I haven't checked but it may be more likely to emit a Z particle and remain an electron. That is the problem I was originally talking about.) If the electron is just in space then we could again "lose" the electron.

I Googled this for a while and couldn't really come up with a good site to supplement this for you. Most articles out there deal with pair production by way of a photon, not production with another kind of field in the area.

Okay, did I answer this to your satisfaction or am I still confusing the issue?

-Dan
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Old Aug 11th 2014, 05:41 PM   #13
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Originally Posted by topsquark View Post
Pair production in the vacuum doesn't need any particles close by to form them. Simply by looking that closely (which brings the problem into the high energy problem) we find the pair production.
Let me try to break it down step by step:
  • By looking closely we are confining the particle to a narrow space which means
  • we are forcing it to sprint like Speedy Gonzales in order not to get caught (which Heisenberg wouldn't be happy about) which means
  • it needs to carry a lot of energy (charge) which means
  • it will encourage pair production from the vacuum.
Now, if the electron is on a racing course inside an atom, it (probably) stays in a confined space no matter what, because of electrostatic attraction to the nucleus which would again force it to sprint like Speedy Gonzales (Heisenberg uncertainty).

Do you think that I'm on the right track, so far?

However this is much easier to do when we have a nearby particle that participates in the field. So your electron in an atom "emits" a weak nuclear force field which eases the difficulty of producing a pair. Another example might make it easier for you to see. Think of it this way: An electron "emits" an EM field because it is charged. Particles then can be affected by that field. It's the same way with the weak field.
Okay, that sounds really cool. Even though I thought that uncertainty would only affect the kinetic energy the electron carries, not its weak field which is responsible for virtual neutrinos saying hello.

In the interaction e --> W- + (electron neutrino) we do "lose" the electron.
Are you sure you didn't mean to say "Z" here? (Just a question.)

(However it is likely to come back quickly if we are doing this with an electron in an atom. I haven't checked but it may be more likely to emit a Z particle and remain an electron. That is the problem I was originally talking about.) If the electron is just in space then we could again "lose" the electron.
Frankly, I still don't see what this has to do virtual neutrino/antineutrino pair production from the vacuum. Seems like we are talking about two different things here.

I Googled this for a while and couldn't really come up with a good site to supplement this for you. Most articles out there deal with pair production by way of a photon, not production with another kind of field in the area.
Thanks for trying, Dan! I'm actually notorious for asking questions hard to answer. - Did I mention that I'm curious?

Okay, did I answer this to your satisfaction or am I still confusing the issue?

-Dan
Well, I still can't satisfactorily visualize the whole thing but we are definitely getting closer. I just hope this wouldn't increase the uncertainty! LOL

-Michael
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Old Aug 12th 2014, 02:23 PM   #14
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Originally Posted by Curious View Post
[*]By looking closely we are confining the particle to a narrow space which means[*]we are forcing it to sprint like Speedy Gonzales in order not to get caught (which Heisenberg wouldn't be happy about) which means[*]it needs to carry a lot of energy (charge) which means[*]it will encourage pair production from the vacuum.[/LIST] Now, if the electron is on a racing course inside an atom, it (probably) stays in a confined space no matter what, because of electrostatic attraction to the nucleus which would again force it to sprint like Speedy Gonzales (Heisenberg uncertainty).
Sounds almost good. Two points:
1) The neutrino does not have a charge and
2) It will always chase down Speedy Gonzales (the fastest mouse in all Mexico) as neutrinos always travel at the speed of light. (ĦAndale! ĦAndale! ĦArriba! ĦArriba!)

Originally Posted by Curious View Post
Are you sure you didn't mean to say "Z" here? (Just a question.)
If we are talking about pair production, this simplest interaction is the one I mentioned already. If we are talking about pair production near the electron then the neutrino and anti-neutrino pop out of the vacuum. If we are talking about scattering from the electron then the reaction is e- + e- --> Z --> e- + e-.

Originally Posted by Curious View Post
Did I mention that I'm curious?
Hey, I'm cool with that. I always pester my profs.

-Dan
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Old Aug 12th 2014, 03:29 PM   #15
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Originally Posted by topsquark View Post
Sounds almost good. Two points:
1) The neutrino does not have a charge and
2) It will always chase down Speedy Gonzales (the fastest mouse in all Mexico) as neutrinos always travel at the speed of light. (ĦAndale! ĦAndale! ĦArriba! ĦArriba!)
1) I am still talking about how the electron might "acquire" virtual neutrino/anti-neutrino pairs.
2) To my knowledge, there is no reliable measurement of Speedy's maximum speed available - but I agree with you that he's rather unlikely to reach anything close to c.

If we are talking about pair production, this simplest interaction is the one I mentioned already.
That would be the e- --> W- + (electron neutrino) interaction. Of course, now you've got to explain where you see a pair coming out of this.

If we are talking about pair production near the electron then the neutrino and anti-neutrino pop out of the vacuum. If we are talking about scattering from the electron then the reaction is e- + e- --> Z --> e- + e-.
Please explain what "scattering from the electron" means.

Also, I still wonder how confining the electron could increase its weak field (supportive of neutrino/anti-neutrino popping out of the vacuum).

Cheers,
-Michael
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Old Aug 17th 2014, 11:13 AM   #16
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Hi Dan,

Have you given up on me?

Michael
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Old Aug 17th 2014, 04:11 PM   #17
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Originally Posted by Curious View Post
Hi Dan,

Have you given up on me?

Michael
Nope. Just spending a few weeks with my parents. It's hard to get to the computer sometimes. I probably should have told you that I wasn't going to be around for awhile. I'll either get to it soon or sometime after the 27th. Sorry about the delay.

-Dan
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Old Aug 17th 2014, 05:37 PM   #18
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Thanks, Dan. I look forward to continuing our interesting conversation.

Michael
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Old Aug 18th 2014, 10:39 AM   #19
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Originally Posted by Curious View Post
1) I am still talking about how the electron might "acquire" virtual neutrino/anti-neutrino pairs.
I'm not sure what you mean by "acquire." Are you talking about how a neutrino could interact with an electron? Probably not, we already went over that a few posts before.

Originally Posted by Curious View Post
That would be the e- --> W- + (electron neutrino) interaction. Of course, now you've got to explain where you see a pair coming out of this.
The neutrino pair would come into existence through an energy fluctuation in the Universe at large. These neutrinos are called "virtual particles" simply because they have not been observed by anything. Once one is detected (perhaps by collision with an electron) the neutrino pair becomes "real."

Originally Posted by Curious View Post
Please explain what "scattering from the electron" means.
A scattering interaction occurs when one particle collides with another and changes the direction of one or both. (That may not be the best description, but it works.) In the example I gave; e- + e- --> Z0 --> e- + e-; the incoming electrons exchange a Z to either attract or repel.

Originally Posted by Curious View Post
Also, I still wonder how confining the electron could increase its weak field (supportive of neutrino/anti-neutrino popping out of the vacuum).
Did I say that at some point? Probably. It's not correct. What I was trying to say (I think) is that the electron carries "weak-hypercharge" and as such the weak field is going to be larger in the area of the electron. It's kind of like being near an object that has mass...the closer you get the larger the gravitational field around it.

I hope I'm getting closer to your answer!

-Dan
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Old Aug 25th 2014, 12:02 PM   #20
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Hi Dan, now I took some time for my reply. So much other stuff going on...

Originally Posted by topsquark View Post
I'm not sure what you mean by "acquire." Are you talking about how a neutrino could interact with an electron? Probably not, we already went over that a few posts before.
No, I was simply trying to express that the presence of the electron would make more virtual neutrinos pop out of the vacuum - especially if the electron carries a lot of energy. Looks like you thought I'm talking about a neutrino, though.

The neutrino pair would come into existence through an energy fluctuation in the Universe at large. These neutrinos are called "virtual particles" simply because they have not been observed by anything. Once one is detected (perhaps by collision with an electron) the neutrino pair becomes "real."
I was wondering where there would be a neutrino pair coming out of the e- --> W- + (electron neutrino) interaction. The electron neutrino in this equation looks like a loner to me.

A scattering interaction occurs when one particle collides with another and changes the direction of one or both. (That may not be the best description, but it works.) In the example I gave; e- + e- --> Z0 --> e- + e-; the incoming electrons exchange a Z to either attract or repel.
Hmm... I thought that two free electrons could only repel one another.

Did I say that at some point? Probably. It's not correct. What I was trying to say (I think) is that the electron carries "weak-hypercharge" and as such the weak field is going to be larger in the area of the electron. It's kind of like being near an object that has mass...the closer you get the larger the gravitational field around it.
Well, I may have read this into your answer as I was thinking of additional virtual neutrinos showing up if the electron were in a high energy situation (as one of your replies suggested). Not sure how this is connected to the weak field then.

Michael

Last edited by Curious; Aug 25th 2014 at 12:05 PM.
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