Weak Interaction Questions

[immijimmi]

1. Weak interaction is the only method by which strangeness and CP can be violated. What's so special about it that it can do this?

2. The only gauge bosons that have mass are both associated with this force. Is that significant?

Edited January 10, 2012 by immijimmi

[Widdekind]

The Weak Force eigenstates are not the same, as the "true" or "mass" eigenstates, of the other Fundamental Forces. So, during Weak interactions, i.e. upon the emission or absorption of Weak bosons [math]\left( W^{\pm}, Z^0 \right)[/math], particles' wave-functions "collapse" into "conformance", with the Weak force, i.e. into Weak eigenstates. And, those Weak eigenstates, e.g. [math]\left( \nu_e, \nu_{\mu}, \nu_{\tau} \right) [/math], are "mixtures" of the "canonical" eigenstates, e.g. [math]\left( \nu_1, \nu_2, \nu_3 \right) [/math], e.g. [math]\nu_e \approx 0.9 \nu_1 + 0.5 \nu_2[/math].

 

In particular, neutrinos only interact Weakly. Er go, after every interaction neutrinos do undergo, they "emerge" from the Weak interaction, in a Weak eigenstate, i.e. [math]\left( \nu_e, \nu_{\mu}, \nu_{\tau} \right) [/math], which are mixtures of the "true" mass eigenstates, e.g. [math]\left( \nu_1, \nu_2, \nu_3 \right) [/math]. And, each of those "true" mass eigenstates, has a different rest mass, and so a different speed, for the same energy. Thus, the "true" components, of neutrinos, constantly interfere with themselves, producing "beats", i.e. neutrino flavor oscillations.

Edited January 12, 2012 by Widdekind

[swansont]

To the extent that I can tell that this is correct, it also seems that it does not address immijimmi's questions at all.

[Widdekind]

Might gluons have mass ? If so, then only EM photons would be mass-less, i.e. massive force-carriers would be the rule, not the exception. By what means do experimenters conclude, that gluons have no mass ?

 

 

 

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To the extent that I can tell that this is correct, it also seems that it does not address immijimmi's questions at all.

I understand, that "what is so special" about the Weak interaction, is that its eigenstates are not orthogonal, to those of (all?) the other interactions, i.e. the Weak-mixing angle. I cannot explain "why" that is so, but I understand that that is "what" differentiates the Weak interaction, from (all?) the others.

Edited January 12, 2012 by Widdekind

[immijimmi]

Might gluons have mass ? If so, then only EM photons would be mass-less, i.e. massive force-carriers would be the rule, not the exception. By what means do experimenters conclude, that gluons have no mass ?

 

 

 

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I understand, that "what is so special" about the Weak interaction, is that its eigenstates are not orthogonal, to those of (all?) the other interactions, i.e. the Weak-mixing angle. I cannot explain "why" that is so, but I understand that that is "what" differentiates the Weak interaction, from (all?) the others.

 

This sounds dense of me, but is there any way you could explain that to an AS physics student? I dont know what the 'weak-mixing angle' or 'orthogonal' mean, and i'm not sure what the intended meaning of 'eigenstates' is in that context. If something has an eigenstate that means that you know the exact values of its quantum numbers. How do you apply that to a force? (I'm quite new to eigenstates too actually so correct me if that last was wrong)

Edited January 20, 2012 by immijimmi

[Widdekind]

This sounds dense of me, but is there any way you could explain that to an AS physics student? I dont know what the 'weak-mixing angle' or 'orthogonal' mean, and i'm not sure what the intended meaning of 'eigenstates' is in that context. If something has an eigenstate that means that you know the exact values of its quantum numbers. How do you apply that to a force? (I'm quite new to eigenstates too actually so correct me if that last was wrong)

 

I understand, that when particles "interact", they have "detected" & "measured" each other, quantum mechanically, i.e. "interactions" cause wave-function "collapses", into eigenstates, of the interaction force (EM/W, S). Apparently, the eigenstates, of the EM,S interactions, are the "canonical" or "mass" eigenstates, e.g. m_e = 511keV. However, the eigenstates, of the W interaction, are special "weak" eigenstates, which are "mixtures", i.e. quantum super-positions, of the canonical mass eigenstates. Vaguely, [math]d_W \approx 0.97 d + 0.22 u[/math]; and [math]\left(\nu_e\right)_W \approx 0.9 \nu_1 + 0.5 \nu_2[/math].

 

Note that the neutrino mass eigenstates, [math]\nu_1,\nu_2,\nu_3[/math], should be depicted on the SM table of particles, to be consistent, with the other fermions, listed according to their mass eigenstates. However, b/c neutrinos only interact weakly, they are only generated into Weak eigenstates, whilst their pure mass eigenstates are not directly observed -- observing neutrinos requires them to interact, which requires the Weak force, which "collapses" all emerging neutrinos into Weak eigenstates. So, logically inconsistently, the SM table of particles lists every other fermion, according to their canonical mass eigenstates; but lists neutrinos according to their "Weak flavors", i.e. Weak eigenstates, [math]\nu_e, \nu_{\mu}, \nu_{\tau}[/math].

[immijimmi]

I understand, that when particles "interact", they have "detected" & "measured" each other, quantum mechanically, i.e. "interactions" cause wave-function "collapses", into eigenstates, of the interaction force (EM/W, S). Apparently, the eigenstates, of the EM,S interactions, are the "canonical" or "mass" eigenstates, e.g. m_e = 511keV. However, the eigenstates, of the W interaction, are special "weak" eigenstates, which are "mixtures", i.e. quantum super-positions, of the canonical mass eigenstates. Vaguely, [math]d_W \approx 0.97 d + 0.22 u[/math]; and [math]\left(\nu_e\right)_W \approx 0.9 \nu_1 + 0.5 \nu_2[/math].

 

Note that the neutrino mass eigenstates, [math]\nu_1,\nu_2,\nu_3[/math], should be depicted on the SM table of particles, to be consistent, with the other fermions, listed according to their mass eigenstates. However, b/c neutrinos only interact weakly, they are only generated into Weak eigenstates, whilst their pure mass eigenstates are not directly observed -- observing neutrinos requires them to interact, which requires the Weak force, which "collapses" all emerging neutrinos into Weak eigenstates. So, logically inconsistently, the SM table of particles lists every other fermion, according to their canonical mass eigenstates; but lists neutrinos according to their "Weak flavors", i.e. Weak eigenstates, [math]\nu_e, \nu_{\mu}, \nu_{\tau}[/math].

 

Maybe I should wait until I understand particle physics more before I attempt to venture into this particular topic...