Neutrino Oscillation: Learn About the Experiment

[SpaceTiger]

In cases where laws come into conflict with theory, it is customary to abandon the theory, not abandon the law.

This is overwhelmingly silly. Conservation laws are themselves a part of theories. The only reason they get the title "law" is because they are used as simple guidelines for deciding the outcome of interactions (much like Newton's Laws are used to decide the outcome of mechanics problems). Conservation of lepton number is a prediction of the standard model of particle physics, a theory which has now been shown to be at least partially wrong.

 

[Michael Mozina]

This is overwhelmingly silly. Conservation laws are themselves a part of theories. The only reason they get the title "law" is because they are used as simple guidelines for deciding the outcome of interactions (much like Newton's Laws are used to decide the outcome of mechanics problems). Conservation of lepton number is a prediction of the standard model of particle physics, a theory which has now been shown to be at least partially wrong.

First of all, let me be clear about my position on this issue. Based on the papers that Carl and others have referenced for me, I am in fact "open" to the possibility that neutrinos "oscillate". Neutrinos however may not "oscillate" at all, but rather they may 'decay' along the way or "change" based on some specific interaction with a particle. Neutrinos may not change flavor all, but rather they may be deflected and absorbed between the transmitter and the reciever. I remain open minded toward all these possibilities.

It seems however that there is what I would call "undue enthusiasm" on the part of "some" astronomers to claim that neutrinos "oscillate" in spite of the seeming violation of known laws of particle physics. The onus of responsibility to prove neutrino oscillation occurs to the exclusion of all other options is on the researchers that make this claim. I am simply looking at this issue "skeptically" just as I would skeptically examine any scientific claim. If their data excluded all other possibilities and their interpretation violated no known "laws" of physics along the way, I'd have no problem with their "oscillation" hypothesis.

There is however a "standard" and accepted practice in science as it relates to the order of presidence between "laws" and "theories". The "accepted" practice is that when theories violate known "laws", the theory is thereby falsified by this conflict. That is typically they way all theories are falsified in fact.

In the case of the SNO paper however, the "laws" of particle physics were said to be falsified based on current solar "theory" and based on current neutrino mass and oscillation "theories". That is exactly backwards from typical and accepted scientific practice. This claim is therefore an "exceptional" claim, and as such, this claim requires "exceptional evidence". So far I've not seen any "exceptional" evidence to justify this claim, though admittedly I've not been through the Minos data thuroughly yet. What I have read suggests that this team has not "ruled out" other so called "exotic" possiblities like decay and scattering/absorbtion. Note that there is a distinct difference between a "missing" (as in scattered/absorbed) neutrino and a "changed" (decayed) neutrino and an "oscillating" neutrino. There are at least three ways to explain "missing" neutrinos.

At the moment, the Minos data does seems to provide evidence of "missing" neutrinos, but that is not even technically evidence of detecting a "changed" neutrino, let alone evidence of "oscillating" neutrinos. As I said, I remain open to the possibility that neutrino flavors "change" or even "oscillate". I'm personally more comfortable with the concept of "change" over "oscillation", but both options remain on the table. Where I have a problem is "assumption" that a "law" of physics is invalid because of a data conflict with a "theory". That is not standard scientific practice, and IMO, there simply isn't enough data (yet) to support such a position.

Normally under a circumstance where a theory violates a law, we then claim the theory is falsified. In this case we are trying to claim the "law" is falsified by a theory.

 

[SpaceTiger]

There is however a "standard" and accepted practice in science as it relates to the order of presidence between "laws" and "theories". The "accepted" practice is that when theories violate known "laws", the theory is thereby falsified by this conflict. That is typically they way all theories are falsified in fact.

Nope. Theories are falsified by observation/experiment, not other theories. If it turns out, after studying it more carefully, that a theory predicts something that has already been falsified by experiment (say, non-conservation of energy in the Newtonian limit), then one can usually dismiss it without making new observations. Neutrino oscillations had not been experimentally tested prior to the first solar neutrino detections, so it couldn't be ruled out that the standard model of particle physics (along with the predicted conservation of lepton number) was wrong.

 

[CarlB]

Dear Michael Mozina,

The experimental evidence shows that the probability of detecting an electron neutrino is a function of distance, and that the function is typically an oscillatory one with the intensity of detected neutrinos going up and down as a function of distance. That in itself should be pretty convincing.

Like I said before, the mystery disappears when you think of the neutrinos as \nu_1, \nu_2 and \nu_3, in their mass eigenstates. Instead, the mystery, such as it is, is why neutrinos are not emitted in mass eigenstates. But none of the other particles are emitted in mass eigenstates so it shouldn't be much of a surprise when the neutinos aren't emitted that way either. Neutrino oscillation is built on pretty much the same principles that "explain" interference between a photon and itself in the 2-slit experiment.

What I'm saying is that neutrino oscillation is a very fundamental part of quantum mechanics and trying to reinterpret the evidence for it is unlikely to work out, UNLESS you are willing to also reinterpret quantum mechanics in general.

The concept of particles being emitted not on their mass shell (so that momentum and energy are not conserved) is a very fundamental part of field theory. Field theory is said to be the most accurate theory ever implemented by man with measurements of the g-2 of the electron now matching theory to something like 20 decimal places of accuracy.

If you want to also throw that away, and you want someone to listen to your ideas, you're going to have to first find some other theory that makes the same predictions.

It's not that I'm at all unsympathetic to the possibility that quantum mechanics needs to be replaced. In fact, I've been saying the same thing for years. But without a theory to replace it, the fact that the theory we have is, well, a bit rough around the philosophical edges, is not interpreted (by very many physicists) as evidence that the theory is wrong.

I worked on this problem for 3 years, but got constant complaints that my mathematics (i.e. Clifford algebra) was too complicated. Eventually I got around to working out consequences for the lepton masses. I eliminated all the difficult to understand "adult mathematics" and the resulting paper got some small amount of attention. My paper:
http://www.brannenworks.com/MASSES2.pdf

extended an empirical relation by Yoshio Koide, who wrote a paper referencing mine here:

http://www.arxiv.org/abs/hep-ph/0605074

And now I'm busily working on the next paper, which will put the adult mathematics back in. If you think that modern physics is crazy, I agree with you completely. But the practitioners are stunningly arrogant, quite certain that they are in possession of the truth, quite certain that amateurs can provide no useful commentary on the subject and are deeply uninterested in our opinions on this. You will get nowhere by pointing any of this out to them.

What I'm trying to say here is that instead of complaining about the darkness, why don't you try to light a candle?

Carl

 

[Michael Mozina]

Dear Michael Mozina,

The experimental evidence shows that the probability of detecting an electron neutrino is a function of distance, and that the function is typically an oscillatory one with the intensity of detected neutrinos going up and down as a function of distance. That in itself should be pretty convincing.

That is convincing evidence that "something" is occurring as a function of distance. Whether that "something" is scattering, absortion, decay or oscillation remains an unknown to me at this time. I personally would lean toward scattering since I have no desire to go outside the confines of laws of particle physics or Quantum Mechanics.

Like I said before, the mystery disappears when you think of the neutrinos as \nu_1, \nu_2 and \nu_3, in their mass eigenstates. Instead, the mystery, such as it is, is why neutrinos are not emitted in mass eigenstates. But none of the other particles are emitted in mass eigenstates so it shouldn't be much of a surprise when the neutinos aren't emitted that way either.

Your links are slow reading but they are very insightful and helpful in understanding a mathematical model to explain the oscillation hypothesis. I still have a long way to go before I feel "comfortable" with the idea, but at least I grasp the basic ideas a bit. I'm willing to let go of the conservation of "mass" concerns I had about this change based on what I've read so far. That math seems to work out, provided we envision the neutrino as having multiple wave forms. I'm more concerned about lepton conservation laws.

Neutrino oscillation is built on pretty much the same principles that "explain" interference between a photon and itself in the 2-slit experiment.

Actually however, there is quite a big difference here since we are violating particle "laws" related to lepton conservation, whereas no such violation is required to explain interference patterns in photons.

What I'm saying is that neutrino oscillation is a very fundamental part of quantum mechanics and trying to reinterpret the evidence for it is unlikely to work out, UNLESS you are willing to also reinterpret quantum mechanics in general.

How exactly do you "know" that neutrino oscillation is a "very fundamental" part of QM? The way I see it, we're are still looking for a way to rule out scattering and decay from oscillation at this point. First you would need to demonstrate to me that we've done this much before you could claim that neutrino oscillation occur, let alone suggest that neutrino oscillation is fundamental to QM in any way. I think you are "assuming" this point, rather than demonstrating this point. Photons are massless. Neutrinos are not massless. There are greater limits on particles with mass, and lepton conservation is one of those limits. That is why we have 'forbidden' decay possibilites.

The concept of particles being emitted not on their mass shell (so that momentum and energy are not conserved) is a very fundamental part of field theory.

But this is in the realm of "particle theory" where particles are assigned specific resting masses. Electrons have a specific resting mass compared to the mass of a proton. Evidently neutrinos have mass as well. Even if we allow for "flavor changing", we must conserve total energy, since that was the basis for suggesting that a neutrino exists in the first place.

Field theory is said to be the most accurate theory ever implemented by man with measurements of the g-2 of the electron now matching theory to something like 20 decimal places of accuracy.

Ok, but how does field theory explain the lepton conservation law violation?

If you want to also throw that away, and you want someone to listen to your ideas, you're going to have to first find some other theory that makes the same predictions.

It's not that I'm at all unsympathetic to the possibility that quantum mechanics needs to be replaced. In fact, I've been saying the same thing for years. But without a theory to replace it, the fact that the theory we have is, well, a bit rough around the philosophical edges, is not interpreted (by very many physicists) as evidence that the theory is wrong.

I think we're talking past one another here just a bit. I'm not suggesting we toss out QM, or conservation laws, or any laws of physics, including particle physics. I'd rather work *inside* these laws and theories rather than outside of them. As I see things "flavor transformation" are a violation of lepton conservation laws. Although I am very confident in the data sets in both the SNO experiements and the Minos experiments, I'm willing to look for "other ways" to explain the data sets that do not violate any known laws of particle physics. I have no need to fixate or concentrate on any explanation for these data sets that does violate any known laws of physics. Since oscillation is the only explanation that requires that lepton laws are invalid, I would be less inclined to consider that explanation over "scattering" or decay processes.

I worked on this problem for 3 years, but got constant complaints that my mathematics (i.e. Clifford algebra) was too complicated. Eventually I got around to working out consequences for the lepton masses. I eliminated all the difficult to understand "adult mathematics" and the resulting paper got some small amount of attention. My paper:
http://www.brannenworks.com/MASSES2.pdf

extended an empirical relation by Yoshio Koide, who wrote a paper referencing mine here:

http://www.arxiv.org/abs/hep-ph/0605074

And now I'm busily working on the next paper, which will put the adult mathematics back in. If you think that modern physics is crazy, I agree with you completely. But the practitioners are stunningly arrogant, quite certain that they are in possession of the truth, quite certain that amateurs can provide no useful commentary on the subject and are deeply uninterested in our opinions on this. You will get nowhere by pointing any of this out to them.

I'm convinced from the "dumbed down" versions I've read that the math works out as it relates to mass. I do not see how it conserves conservation of lepton orientation laws. I think that's my only beef to date with any of the math I've seen.

What I'm trying to say here is that instead of complaining about the darkness, why don't you try to light a candle?

Carl

I hear you on this point. I would say there probably is a way to explain the Minos data in terms of scattering related to energy states. I'd say that math is bit over my head at the moment, but I think that would be a more productive avenue than debating interpretations of data sets at a theoretical level only.

 

[CarlB]

That is convincing evidence that "something" is occurring as a function of distance. Whether that "something" is scattering, absortion, decay or oscillation remains an unknown to me at this time. I personally would lean toward scattering since I have no desire to go outside the confines of laws of particle physics or Quantum Mechanics.

When you look for the number of neutrinos of a given flavor as a function of distance from the source you find that as the distance increases, the number you detect goes down (which is compatible with scattering absorption, decay and oscillation) and goes up (which I think is compatible only with oscillation), depending on just how far you are from the source.

If neutrino oscillation were outside the confines of the laws of particle physics or quantum mechanics, believe me, someone would have noticed it by now.

The fact that neutrinos have a flavor basis and a mass basis that are distinct is an old idea but one that didn't have to be explored until it became known that neutrinos do, in fact, have mass. But the same concept was present in the standard model dating back to the Cabibbo angle.

In addition to neutrinos having a different flavor basis from mass basis, the same can be said of the quarks. In the literature, the flavor basis for quarks is denoted by a prime, as in d', s' and b' or u', c', t'.

You see, which type of quark you choose to have two different bases, the up quarks (u,c,t) or the down quarks, depends on your preference only. For a good explanation of this, see the book by Chen, "Quarks, Leptons and Gauge Fields", which was the text I learned from so many years ago. The usual preference you see is to keep the up quarks with a single basis and let the down quarks have two different bases. With that choice, the quarks are written {u,c,t,d,s,b,d',s',b'}. The conversion from {d,s,b} to {d',s',b'} is by the CKM matrix, which dates to 1963:
http://en.wikipedia.org/wiki/CKM_matrix

The same thing can be said about the leptons. Instead of treating the charged leptons as having a flavor basis identical to their mass basis, and the neutrinos as having two bases, we could just as easily reverse the situation and let the charged leptons have two bases and keep the neutrinos as described with a flavor basis equal to their mass basis.

The current situation is that the leptons are $$\{e,\mu,\tau,\nu_1,\nu_2,\nu_3,\nu_e,\nu_\mu,\nu_\tau\},$$ with the MNS matrix showing how to convert between the two bases for the neutrinos, but one could just as easily keep only one set of neutrinos and split the charged leptons into a mass basis and a flavor basis.

These choices were made for historical reasons and there is no reason whatsoever in the math to choose one over the other. Also what I'm saying here is that the violation of flavor conservation was already present in the quarks (and was known to great accuracy for decades) so it wasn't too much of a surprise to see it also present in the leptons. If anything, the addition of neutrino mass (and therefore neutrino oscillations) has made the standard model more simple. The particles are more consistent now.

The only law which is getting violated is lepton family conservation, which is a pretty small law. The equivalent conservation law for baryons was already known to be violated. Here is an easy to read explanation:
http://en.wikipedia.org/wiki/Flavour_(particle_physics)

Carl

 

[Michael Mozina]

When you look for the number of neutrinos of a given flavor as a function of distance from the source you find that as the distance increases, the number you detect goes down (which is compatible with scattering absorption, decay and oscillation) and goes up (which I think is compatible only with oscillation), depending on just how far you are from the source.

Which data specifically are you referring to where flavors "increase" over distance? Do you mean they increase in terms or raw numbers of hits or simply percentages relative to other types of neutrinos? We might have different energy states of neutrinos being scattered/absorbed at different rates, which may change "percentages" over a distance but it should result in fewer actually numbers of neutrinos received as we increase the distance.

On the other hand, some neutrinos may be more sensitive to the matierals they pass through than others. Increases in terms of percentages of relative neutrinos isn't necessarily a problem as it relates to scattering rates, whereas an increase in raw detections would be a different issue. I'm not sure which you are suggesting is the case here.

Even in this case an absorption/emission process that involves a one time change in "flavor" could not be eliminated as the "cause" for this change.

If neutrino oscillation were outside the confines of the laws of particle physics or quantum mechanics, believe me, someone would have noticed it by now.

Well, I'm sure that others have "noticed" that there is a lepton conservation particle physics law that is being violated. Like all debates, I'm sure I'm not the only one to notice this apparent problem. Here is the way I see things:

If we are going to throw lepton conservation laws of particle physics out the window, then wouldn't we expect to see this violation from the very start? We should be able to see and measure change over distance in any of the possible senarios that we are considering. Shouldn't we expect to see "forbidden" reactions violated immediately if lepton conservation laws are not actually applicable to these interactions?

If there are forbidden emissions from the outset, then what "causes" this violation to occur once the emission enters the quantum streams? Is it an internal decay process, an internal oscillation process, or something related to absorption and/or scattering?

Even in particle physics, there are laws and specifically conservation laws that are used to guide particle "theory", and used to determine which particles emissions are possible and which are not. This is one such "law". If the "guideline" is wrong, then why don't we see this violation immediately? If we don't see this violation immediately, how do we determine if this is purely an "internal" conversion process as opposed to a QM 'interaction' with the outside world?

The fact that neutrinos have a flavor basis and a mass basis that are distinct is an old idea but one that didn't have to be explored until it became known that neutrinos do, in fact, have mass. But the same concept was present in the standard model dating back to the Cabibbo angle.

The early "excitement" about neutrinos having mass came about through early experiments that provided evidence to suggest that muon neutrinos are more "massive" than electron neutrinos. Based on the various lepton sizes, that does logically makes sense. Since a Tau lepton is nearly 3500 times the size of an electron, I can understand how a Tau Neutrino could also contain more mass than both of the other flavors of neutrinos.

In any scenario we might use to explain the neutrino data sets, we *must* obey at least the laws of conservation of total energy, since that was the point of adding neutrinos in the first place. Creating a single "maga-multiple-wave particle" out of a single neutrino has it's own set of problems related to explaining different masses for different neutrinos. In essense you are suggesting that they do *NOT* have different masses afterall, but a "total mass" that is based on three different masses and contains all three masses! Now an electron neutrino has to carry the mass of three masses/waves, not just one! In essense we're now suggesting that there really isn't a "single" resting mass for any neutrino, and this sort of throws the first evidence right out the window from my perspective.

The only law which is getting violated is lepton family conservation, which is a pretty small law. The equivalent conservation law for baryons was already known to be violated. Here is an easy to read explanation:
http://en.wikipedia.org/wiki/Flavour_(particle_physics)

If it's a "small" law that is getting violated, why are their forbidden decay possibilities, and why aren't we noticing this violation immediately, right at the transmitter?

 

[CarlB]

Which data specifically are you referring to where flavors "increase" over distance? Do you mean they increase in terms or raw numbers of hits or simply percentages relative to other types of neutrinos?

The number of hits increases in absolute number of "raw hits". What was not there at all at short distances, begins to appear. And then that flavor disappears again, and then it reappears again. Furthermore, this happens repeatedly.

Even in this case an absorption/emission process that involves a one time change in "flavor" could not be eliminated as the "cause" for this change.

Let's see... The neutrino detector experiments generally give good information on the direction of travel of the received neutrino. It would be rather difficult to explain how a scattered beam of flavor changed neutrinos managed to keep traveling in the same direction. Especially if you're going to ascribe a different mass to the different flavor neutrinos (which is not quite the way that the standard model is put together by the way).

If we are going to throw lepton conservation laws of particle physics out the window, then wouldn't we expect to see this violation from the very start? We should be able to see and measure change over distance in any of the possible senarios that we are considering. Shouldn't we expect to see "forbidden" reactions violated immediately if lepton conservation laws are not actually applicable to these interactions?

Lepton number is conserved in neutrino oscillation, what you meant to write was "lepton flavor conservation" sometimes called "LFC". Conservation laws appear when experiments seem to show that something is conserved, and then they disappear when experiments show otherwise. In the case of lepton flavor conservation, the effect is suppressed by the low masses of the neutrinos, so the effect is difficult to see.

An intuitive way of explaining this is to note that the neutrino masses are very very small. Thus they typically travel at extremely high speeds, very close to the speed of light. At such high speeds, their clocks (proper time) run very slow so they don't have a lot of time available to do interesting things.

The quarks are much heavier, and therefore slower, and so their mixing is much easier to see (and like I said, this dates back to 1963 in the theoretical literature, which was motivated by experimental observations).

Even in particle physics, there are laws and specifically conservation laws that are used to guide particle "theory", and used to determine which particles emissions are possible and which are not. This is one such "law". If the "guideline" is wrong, then why don't we see this violation immediately? If we don't see this violation immediately, how do we determine if this is purely an "internal" conversion process as opposed to a QM 'interaction' with the outside world?

Like I said before, if you have a clue on how to write down an alternative explanation that explains the data, write it down. But there is a heck of a lot of data and it is going to be kind of difficult to explain. I'm hardly the poster child for believing in the standard model of particle physics, but I have no doubt about these things.

In any alternatives to the standard model, the difficulty is in the details. My hope for redoing this stuff is based on deriving the standard model itself from a very small number of very simple (deeper) first principles. That way instead of having to redo all the calculations of the standard model (which is so successful), I can subsume them into the deeper theory.

The early "excitement" about neutrinos having mass came about through early experiments that provided evidence to suggest that muon neutrinos are more "massive" than electron neutrinos. Based on the various lepton sizes, that does logically makes sense. Since a Tau lepton is nearly 3500 times the size of an electron, I can understand how a Tau Neutrino could also contain more mass than both of the other flavors of neutrinos.

This really isn't the way that these things are described in the current literature. The flavor neutrinos: the electron neutrino, muon neutrino and tau neutrino do not have masses in the sense that a particle like an electron has a mass. The neutrinos that do have exact masses are mixed from combinations of the flavor neutrinos. And as I mentioned before, exactly the same situation has been present with the quarks for 43 years, slightly longer than half the time that quantum mechanics has been in existence.

In any scenario we might use to explain the neutrino data sets, we *must* obey at least the laws of conservation of total energy, since that was the point of adding neutrinos in the first place.

Quantum mechanics hasn't had conservation of energy for "virtual" particles since the early 1940s. The calculations for neutrino oscillation are done as virtual particles. In fact, if you'll read Alexei Smirnov's notes, you will see that they can sometimes treat neutrinos "as if" they were on their mass shell. But mass shells are approximate things. Neutrino masses are very small, so that's a very thin shell.

In essense you are suggesting that they do *NOT* have different masses afterall, but a "total mass" that is based on three different masses and contains all three masses! Now an electron neutrino has to carry the mass of three masses/waves, not just one! In essense we're now suggesting that there really isn't a "single" resting mass for any neutrino, and this sort of throws the first evidence right out the window from my perspective.

The three mass eigenstate neutrinos, $$\nu_1, \nu_2, \nu_3$$ have exact masses. The "electron neutrino" you're talking about is a mixture of these neutrinos. If you don't like thinking about particles that carry mixtures of masses, then you need simply conclude that there is no such thing as an "electron neutrino". In fact, this is the way I prefer to think about it, as it is compatible with Bohmian mechanics.

Thinking about it this way, the emission of an electron neutrino gets replaced by the emission of a set of three neutrinos with three different masses. Each of these propagates separately. Each of them has (more or less) some chance of interacting with an electron, some chance of interacting with a muon and some chance of interacting with a tau. (I'm ignoring the differences between particles and antiparticles here for simplicity.)

So when you see an electron knocked loose by the incoming neutrino, was the incoming neutrino of type 1, 2 or 3? The answer is that you cannot tell, unless you make an explicit measurement of the incoming neutrino's mass, because quantum mechanics requires that all possible ways of making an interaction be added up (i.e. sum the Feynman diagrams), and only then are probabilities computed.

This fact, that ALL the Feynman diagrams contribute to an amplitude before the amplitude is converted (squared absolute magnitude) is the essential mystery of quantum mechanics and is also present in things like the two slit experiment (recall that Feyman said that the complete mystery of QM lies in just the 2 slit experiment).

If it's a "small" law that is getting violated, why are their forbidden decay possibilities, and why aren't we noticing this violation immediately, right at the transmitter?

Neutrinos are very light, so they tend to fly off before you get a chance to anything odd with them.

I think you're gradually beginning to "see the elephant". Quantum mechanics is an ugly subject, but this long predates neutrino oscillations. What is going on here is the essential mystery of QM, how it is that the photon travels down two paths at the same time. In this case, it is three neutrinos that get emitted at the same time.

Instead of two paths taken by the same particle, the essential mystery of QM is here being expressed in three paths that are taken by three different particles, namely the three different mass neutrinos, and yet they interfere with each other (and therefore produce oscillations).

Now in Bohmian mechanics, one supposes that only one of those three neutrinos was actually emitted. However, the two that were not still contribute to the "guiding wave". In the Many-Worlds interpretation, I suppose the three neutrinos are emitted in three different universes, which somehow interfere with each other. The result is that in one universe, the interaction was by a type 1 neutrino, in another it was type 2, etc., and in some other universe there was no interaction at all.

I think that this example is a great way of explaining quantum mechanics. Yes, the elephant is strange.

Now I could put all this into a context where it would make sense (and is no longer a mystery at all), but to do this, I'd have to rewrite pretty much everything you know about physics. As a start, you might consider how you would go about designing a universe if you were God. If you allow only waves, then things tend to flatten out. To get sharp things, so that you can arrange for a universe populated by moral creatures, you need to have matter defined in some sort of point-like manner.

But to get point like objects to interact is very very hard. The classical solution is to postulate fields that act at a distance, but these require that one install a bit too much magic in your universe for me to understand. For example, you would have to have two different types of objects in your universe, matter and waves, which is an extra complication. What God did was figure out how to get the whole thing done with just (point like) matter. And to do it, he had to mess around with time a little.

Carl

 

[jtbell]

If it's a "small" law that is getting violated, why are their forbidden decay possibilities, and why aren't we noticing this violation immediately, right at the transmitter?

When you produce (say) a muon-neutrino, it takes time for the probabilities of it interacting as an electron-neutrino or a tau-neutrino to deviate from their initial values of zero. So if you were to detect a neutrino immediately after it was produced, you wouldn't observe any oscillation! In "ordinary" accelerator-based neutrino experiments, the distance between the production site and the detector is not zero, but nevertheless short enough that the neutrinos don't have enough time or distance to oscillate enough for the effects to be visible against the inevitable "background" of interactions that mimic the ones that you're looking for, but really aren't.

During the 1980s, many accelerator-based neutrino experiments analyzed their data to search for neutrino oscillations. I did one such analysis as my Ph.D. dissertation. Nobody found anything, but they were able to set limits on key parameters that determine the size of neutrino-oscillation effects. The parameters deduced from the current successful neutrino oscillation experiments are of course consistent with those limits.

 

[Michael Mozina]

The number of hits increases in absolute number of "raw hits". What was not there at all at short distances, begins to appear. And then that flavor disappears again, and then it reappears again. Furthermore, this happens repeatedly.

Well, that phenomenon also happens repeatedly with photons with only a single wave function, as interference patterns emerge. I'm not sure that phenomenon is an insurmountable hurdle for the the single wave (scattering) option, however it does seem to suggest that the particles are not simply decaying into another type. That phenomenon would seem to favor oscillation over a one time decay.

I will try to respond to the rest of your post later today as things settle down here at work. I want to express my appreciation for the time and effort that you, jtbell, ST and others have put into this discussion. Even if we ultimately "agree to disagee", I certainly appreciate the time that has been spent to carefully answer all my questions. That has been extremely helpful and very much appreciated.

 

[Michael Mozina]

Let's see... The neutrino detector experiments generally give good information on the direction of travel of the received neutrino. It would be rather difficult to explain how a scattered beam of flavor changed neutrinos managed to keep traveling in the same direction.

I will break my response into a few parts since there are several issues being discussed here, and the posts are getting rather lengthy.

If is is "ok" to view the neutrino as one particle with three wave states of mass, then it would be equally approrpiate to treat all individualised neutrinos as individualized particles/waves that can be sensitive to "distance" as it relates to detection. I do not think we can use an apparent "oscillation" in detection rates with distance as an automatic guarantee that all waves are located inside the same particle. In otherwords the detection rate of a tau neutrino may be a function of the tau wave, and the muon detection rate determined by the muon wave in the muon neutrinos, etc. If the detection likelikehood changes with the individualized wave function of the neutrinos, then I think the results would still be consistent with observation. You seem to be suggesting that wavefunction observation can only be consistent with a "single" particle with three different states, instead of three particles with three different wave forms. I'm not sure we can make that leap of faith.

Especially if you're going to ascribe a different mass to the different flavor neutrinos (which is not quite the way that the standard model is put together by the way).

Well, the idea here is that neutrinos are the "leftover" bits of matter/energy that contain and conserve the "leftover" kinetic and momentum from various decay processes. When we talk about a muon decay, there is only so much total energy that can be "leftover" from such a decay. In a Tau decay however, being more massive particles to begin with, it's entirely possible that there is more "leftover" total energy from a decay process of a Tau particle. I'm open to these leftover masses being "close" but not the same or being quite different. There is some logic to believing that since their are various sizes associated with these different particles and decay processes, that the different neutrino masses relate directly to the different sizes of the parent particles.

In a "combined" neutrino view, you have one particle carrying *all* the mass from all three kinds of particles within the same "grouping", whereas I would simply separate the groups of waves into individual particles with separate wave functions (related to the size of the parent lepton. I would suggest that neutrinos are more prone to detection at different locations based on the arrangment the internal neutrino wave at the location of the detector. I would not think that much of the math would necessarily be all that different, but particles would have to be treated as separate waveforms with detection rates determined by the internal wave function of that flavor of neutrino.

 

[CarlB]

If is is "ok" to view the neutrino as one particle with three wave states of mass, ...

As far as I know, no one is doing this, so I don't know where you get the idea that it is "ok". When a neutron decays, it emits one neutrino. Our problem is that it is very difficult for us to determine the mass of that neutrino. We do know is that there could only be one neutrino emitted, but we cannot tell which mass it had (in general). For simplicity, instead of trying to keep track of this sort of detail, the usual method is to call this neutrino an "electron neutrino", but if you demand that particles have sharp masses, then there is no such particle.

Now there is a way that we could be sure which neutrino was emitted. If the amount of energy involved in the decay was so small that there was not enough to create either of the two heavier neutrinos, then, yes, you'd know exactly which neutrino was emitted (from energy considerations), and it would be the light one.

There is a physical situation where this effect is seen (or you might say, expected to be seen), and that is double beta decay. In double beta decay, a single beta decay is forbidden on energy conservation grounds, but two simultaneous decays is allowed. There is a possibility that such a decay could be neutrinoless. The experimental situation is currently a matter of a bit of a nasty academic debate. A good source of links is here:
http://www.nu.to.infn.it/Neutrinoless_Double_Beta_Decay/

My reason for being interested in this is that it is one of the few experiments where the absolute masses of the neutrinos (rather than differences between their squares) can be measured.

... then it would be equally approrpiate to treat all individualised neutrinos as individualized particles/waves that can be sensitive to "distance" as it relates to detection.

Yes, but you're going to have to explain why it is that distance just happens to cause one neutrino type to disappear exactly as much as the other neutrino types appear. In short, this is a tough row to hoe.

Well, the idea here is that neutrinos are the "leftover" bits of matter/energy that contain and conserve the "leftover" kinetic and momentum from various decay processes. When we talk about a muon decay, there is only so much total energy that can be "leftover" from such a decay. In a Tau decay however, being more massive particles to begin with, it's entirely possible that there is more "leftover" total energy from a decay process of a Tau particle. I'm open to these leftover masses being "close" but not the same or being quite different.

It's not the mass that is required to be conserved, it is the energy. Mass can be converted into energy according to Einstein. So a neutrino with mass 0.05 eV can take away any amount of energy so long as that amount is greater or equal to 0.05eV.

Let's look at it from the point of view of neutron decay. A neutron (in empty space) decays with a time constant of 20 minutes. The reason that the decay is energetically favored (or at least not forbidden) is that the mass of the neutron is greater than the total of the masses of the proton, electron plus the neutrino. Let us figure it out with the latest data from the Particle Data Group ( http://pdg.lbl.gov/2005/tables/bxxx.pdf http://pdg.lbl.gov/2005/tables/lxxx.pdf ).

$$\begin{array}{rcc} \textrm{Particle}&\textrm{Mass (MeV)}&\textrm{error}\\ \textrm{neutron}&939.56536 &\pm 0.00008\\ \textrm{proton} & 938.27203 &\pm 0.00008\\ \textrm{electron}&0.51099892&\pm 0.00000004\\ \textrm{neutrino}&0.00000010&\pm 0.00000010\end{array}$$

In the above, I've put an arbitary neutrino mass of 0.1 eV. In reality, nobody knows the neutrino masses. Well, I do have my ideas (see http://www.brannenworks.com/MASSES2.pdf for my latest guess), but we do know that all three of the neutrino masses are somewhere around the number given, and probably considerably less.

Summing up the proton, electron and neutrino masses, we get 938.78302902 +- 0.00008 (notice that the neutrino masses get lost in the error bars of the proton mass which is also much larger than the error bars of the electron mass), which is smaller than the neutron mass by 0.78233098 +- 0.00016. Thus when a neutron decays, the amount of change in mass is so much larger than any of the neutrino masses that the concept that mass is conserved cannot place any restriction on which neutrino is emitted. (That is, any of the three neutrinos is possible).

Now, by the laws of QM, one must add together all the ways that a process can take place before computing absolute values and getting a probability. In the case of oscillations and the like, the way we tell that a (anti) neutrino was emitted was by absorbing it. Perhaps the absorbtion is by the conversion of a proton to a neutron. The same sorts of mass differences would apply to this process, so again, we would be unable to distinguish which mass neutrino was involved.

Since we cannot distinguish which mass neutrino was the one involved, we must add up all the possible ways for the reaction to proceed. In this case, the reaction is the conversion of a neutron to a proton and an electron and a "something" at the source, and the conversion of a proton to a neutron and a positron (or an electron is absorbed) at the other end. Such a reaction cannot specify which mass neutrino was exchanged. Accordingly, by the laws of QM, we must sum the complex numbers associated with all three ways it could happen, and then take the absolute value of that complex number.

Note that in this way of describing the situation there is no oscillation per se. Instead, what you have is an interference between the three different mass neutrinos that could have been emitted and absorbed.

Now the neutrino masses are so small that we can see that it is always going to be very difficult for us to tell which of them we are dealing with. Any process where a light neutrino is emitted and absorbed can also be thought of as a process where a midweight or a heavy neutrino was absorbed. Their masses are so very light.

So instead of talking about the three neutrinos with sharp masses, physicists talk about the three neutrinos characterized by the conversion of electron, muon and tau. In this basis, there is no longer sharp masses involved, but the loss in accuracy is so very small that it doesn't matter. And in this basis, the neutrinos oscillate (instead of interfering).

I think your questions have been very good at digging out exactly what is going on in this process. Thanks for making me go through it. I think my understanding of the neutrinos has increased in that I now appreciate that the flavor neutrinos are not the way that they should be looked at. It is the massive neutrinos that are fundamental.

Carl

 

[Michael Mozina]

Thank you Carl for a very interesting and informative discussion. I can't say that I agree at this point that neutrinos change flavor in mid flight, but I do at least see where you coming from and many of my original objections have been addressed. I still see no specific data that would lead me to believe that the three wave forms of mass are combined into one neutrino rather than just assuming that the position of the wave may affect our ability to detect them at different distances. I do at least however have a much better understanding of the concept, and I very much appreciate your time and effort and the efforts of everyone that participated in this discussion. Thanks.

 

[Michael Mozina]

http://www.yale.edu/opa/newsr/07-04-12-05.all.html

Hey Carl, I was wondering what you thought of the new MiniBooNE data, and whether or not you are still convinced that lepton conservation laws are being violated?

 

[moonstroller]

Is there a nutrino transmitter?