Different masses of particles and anti-particles

  • #1
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Main Question or Discussion Point

The new measurements of neutrinos show that particles have different masses as anti-particles.
Somewhere on this forum I read a link to an article that this is against to rules of special relativity.
How it is with this and how it is with consequences of neutrinos anti-neutrinos mass difference?
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Answers and Replies

  • #2
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The new measurements of neutrinos show that particles have different masses as anti-particles.
I think it is far too early to conclude that.
 
  • #3
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Yes, it is to early. They wait on three sigma.
But, somewhere there was one article, that this is against rules of special relativity. What is this article?
 
  • #4
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My impression was (from reading Weinberg) that quantum mechanics and special relativity (plus some reasonable assumptions) lead to quantum field theory along with its existence of anti-particles of equal mass. So I'd would expect differing masses to be a violation or SR.

Sorry, I don't know which article you are seeking.
 
  • #5
fzero
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There's this article by Greenberg, "Title: CPT Violation Implies Violation of Lorentz Invariance" http://arxiv.org/abs/hep-ph/0201258

"An interacting theory that violates CPT invariance necessarily violates Lorentz invariance. On the other hand, CPT invariance is not sufficient for out-of-cone Lorentz invariance. Theories that violate CPT by having different particle and antiparticle masses must be nonlocal. "
 
  • #6
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Thanks.
1. Is it possible to say the main idea from article, because it is very formalistically written?
2. But how it is with K_0 and its anti-particle? Their masses are the same, but their "derivations" have a little difference.
 
  • #7
A. Neumaier
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The new measurements of neutrinos show that particles have different masses as anti-particles.
Who is claiming that? Your reading is probably a misunderstanding. Note that there are three kinds of neutrinos, and their masses are most likely different.

There's this article by Greenberg, "Title: CPT Violation Implies Violation of Lorentz Invariance" http://arxiv.org/abs/hep-ph/0201258
"Theories that violate CPT by having different particle and antiparticle masses must be nonlocal. "
Yes. Weinberg's book shows that in any local covariant QFT, CPT holds and observable particles and antiparticle have the same mass. Otherwise it is impossible to construct the relevant asymptotic state spaces with causal commutation rules.

The masses are the same, all other quantum numbers (if there are any) have opposite sign. If there are no other quantum numbers (such as for photons), a particle is its own antiparticle.
 
  • #9
A. Neumaier
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They don't give a source with the details. But they write:

''there is a still a five percent probability that Δm2 is actually the same for neutrinos and antineutrinos. With such a level of uncertainty, MINOS physicists need more data and analysis to know for certain if the variance is real.''

Which means, the effect is not yet for real.

''the MINOS results [...] are the first observation of a potential fundamental difference that established physical theory could not explain.''

Indeed, it would contradict the whole foundations of quantum field theory.

But before the community of physicists would conclude that, one would first look for alternative interpretations of the data (which always exist) - it could perhaps be postulating a new neutrino-like particle, or so.


How it is with K_0 particles, as I asked also?
Nothing is wrong with this particle. What do you mean by ''derivations''?
 
  • #10
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''there is a still a five percent probability that Δm2 is actually the same for neutrinos and antineutrinos. With such a level of uncertainty, MINOS physicists need more data and analysis to know for certain if the variance is real.''

Which means, the effect is not yet for real.

''the MINOS results [...] are the first observation of a potential fundamental difference that established physical theory could not explain.''

Indeed, it would contradict the whole foundations of quantum field theory.

But before the community of physicists would conclude that, one would first look for alternative interpretations of the data (which always exist) - it could perhaps be postulating a new neutrino-like particle, or so.
Indeed, this is what the paper http://arxiv.org/pdf/1002.4452 suggests, where they speak only about ''apparent CPT violations''.
 
  • #11
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I do not remember names now, but it is an old measurement with these two particles, whose create two particles (let say) K_0_short lived and K_02_long lived, which have a little different masses. It was obtained sinusoidal variation with time.
Ratio of their decay time is aproximately 137.

It is a known experiment, but I do not remember it more precisely in this moment.
 
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  • #12
A. Neumaier
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I do not remember names now, but it is an old measurement with these two particles, whose create two particles (let say) K_O1 and K_02, which have a little different masses.
Ah, you wrote ''derivations'' but meant ''deviations''?

The recent paper http://arxiv.org/pdf/1011.0127 gives in (35) a stringent upper bound on the mass difference between the neutral kaon and its antiparticle. Thus CPT seems conserved, confirming local QFT.

Of course, there are the well-known CP violations, but there is no significant deviation from the standard model.
 

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