beta decay

[Norman Albers]

I am reading Feynman Lectures Vol.II, p.52-11. Cobalt in a magnetic field produces beta decay with electrons preferentially going out the South pole, a striking state of affairs. This is not such a mystery, though, if you correlate the electron spin with the current sense in the magnet coils. If I am correct that electron spin has a fixed relation to its velocity vector, then there is the answer, no?

[swansont]

The electron spin is correlated with the velocity, but you don't get both orientations, you only get one. That's the issue. The magnetic field polarizes the atoms. If parity were conserved, there would be no preference for N vs S.

[Norman Albers]

Yes, and electron magnetic moment is antiparallel to its spin. The results show angular momentum tending to be opposite velocity. This says to me that the electron magnetic moment is produced opposite to the B-field, thus in a lower energy configuration. This suggests to me the interaction is strongly magnetic. The whole thing is a major little enlightenment for me, having found this a bit mystical. It's not! Rather it is where we had to let go of a principle, CP symmetry, and go further. Thus CPT symmetry, including time reversal and antimatter, does show symmetry. Is this where we start playing with time-reversed waves? I guess we could be anti-people moving backwards in time. Quantum non-locality can be presented as a sum of "past" and "future" waves; I am mystified here.

[swansont]

Yes, and electron magnetic moment is antiparallel to its spin. The results show angular momentum tending to be opposite velocity. This says to me that the electron magnetic moment is produced opposite to the B-field, thus in a lower energy configuration. This suggests to me the interaction is strongly magnetic. The whole thing is a major little enlightenment for me, having found this a bit mystical. It's not! Rather it is where we had to let go of a principle, CP symmetry, and go further. Thus CPT symmetry, including time reversal and antimatter, does show symmetry. Is this where we start playing with time-reversed waves? I guess we could be anti-people moving backwards in time. Quantum non-locality can be presented as a sum of "past" and "future" waves; I am mystified here.

 

You have to look at the whole, though, and not just one example. It's not a magnetic interaction, and I don't think you can explain the weak interaction (below the electroweak unfication threshold) as a magnetic phenomenon.

[Norman Albers]

Thanks, I shall look further. Would you agree there is here a preferred low-energy state magnetically? I read something like seven to one probability. You seem to infer that we are not seeing a fundamental clue here, but I say it is clearly logically connected.

[Meir Achuz]

Thanks, I shall look further. Would you agree there is here a preferred low-energy state magnetically? I read something like seven to one probability. You seem to infer that we are not seeing a fundamental clue here, but I say it is clearly logically connected.

The electron spin direction in beta decay has nothing to do with magnetism.

The V-A nature of the weak interaction makes the helicity of the electron

H=-v/c.

[swansont]

If I had to venture a guess, I'd say that the 7:1 describes the purity of the nuclear polarization, since you'd have thermal noise disrupting the orientation of some of the atoms. This a temperature-dependent phenomenon for a given field strength; I think this dismisses your hypothesis right there.

[Norman Albers]

If I had to venture a guess, I'd say that the 7:1 describes the purity of the nuclear polarization, since you'd have thermal noise disrupting the orientation of some of the atoms. This a temperature-dependent phenomenon for a given field strength; I think this dismisses your hypothesis right there.

Why do you think this? Say, Meir, can you help me get into what you offer, namely V-A whatever? This is new to me, as I have never done nuclear theory per se. Are you saying that there is process to be appreciated at the nuclear level that is only coincidently related to the atom's alignment? It is, I guess, only the nuclear magnetic moment and its alignment about which we speak. Temperature washes out the alignment, that's all. Is the point that I can say how the electron and neutrino spins must add to the unit of change from <5> to <4> in nuclear spin, but that I cannot say why electron velocity is opposite its spin? Actually I'm quite confused: are nuclear spin and magnetic moment parallel, and, do they point South?

[Meir Achuz]

can you help me get into what you offer, namely V-A whatever? This is new to me,

I'm afraid I got ahead of you. You really need the Dirac equation

(in relativistic QM) to understand the V-A theory. You could get some idea from a book on modern physics or a text on "weak interactions".

[Norman Albers]

Thank you, these educational clues are helpful and appreciated. I am hungry to learn of these things and do need to figure out books to seek out. I have spent a lot of time studying helicity in the electromagnetic field, so my background is, I think, good. It's not clear to me if we saying that the preferred emission happens WRT nuclear orientation or if it happens only when we apply a lab field. Can we know if randomly oriented atoms show the same vector correspondence? Namely, spin opposite velocity in the electrons.

[swansont]

In a beam of electrons you can have spin up and spin down, as the Stern-Gerlach experiment showed. The revelation of beta decay is that parity is violated.

[Norman Albers]

In a beam of electrons you can have spin up and spin down, as the Stern-Gerlach experiment showed. The revelation of beta decay is that parity is violated.

I'm afraid I don't see how your answer connects clearly to my questions. It seems to me easy to correlate axial vectors; the mystery is including a polar velocity here. I am asking about the role of the lab field. It is not clear from what I have yet read, that its presence is not part of the cause here. I do know what you are saying. It seems the question is more one of velocity preferedness being distilled out of nowhere, in this context.

[Norman Albers]

I'm afraid I got ahead of you. You really need the Dirac equation

(in relativistic QM) to understand the V-A theory. You could get some idea from a book on modern physics or a text on "weak interactions".

Yes, reading Wikipedia on 'weak interaction' shows that I am right up against the whole construction of the standard model. At least I got the definition of V-A: Vector minus Axial theory, and I thank you for pointing me in this direction. My own attitude allows me to pose the question: "Since relativity shows the equivalence of mass and energy, why can we not characterize the question of mass by asking how and why does energy form stable, localized states?" I have achieved powerful suggestions through inhomogeneous electrodynamics. When people speak of mass stemming from Higgs field and Higgs bosons, it has never made sense to me. It would make sense if we are referring to the establishment of the lower temperature order wherein symmetry is broken, in the range of gigavolt cooling.

[Norman Albers]

In a beam of electrons you can have spin up and spin down, as the Stern-Gerlach experiment showed. The revelation of beta decay is that parity is violated.

I am not clear on S-G filters applied to spins parallel or anti- with velocity. Can we get signal this way on randomly oriented decays? Maybe a collimator to the right and some electrical acceleration upward?

[Norman Albers]

I'm trying to understand the evolution of our antiparticle theory vis-a-vis the CP revolution. Wasn't that well established already, so that this symmetry violation had to be grafted into both sides of what is otherwise symmetric? I read that all other levels of interaction show no violation.

[Norman Albers]

The term "axions" was named as the concept to "clean up the problem". You have to appreciate the sense of humor.