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Fermilab Confirms Evidence of 4th Flavor Neutrino
eldavojohn writes "We've only had evidence for three kinds of neutrinos so far, but a recent test at Fermilab involving an antineutrino beam has reinforced a Michigan researcher's earlier experiment suggesting a fourth flavor. What's really odd about this is that a prior neutrino test (carried out as part of project MiniBooNE) did not result in indications of such strange oscillations. According to the researcher, 'The simplest explanation involves adding new neutrino-like particles, or sterile neutrinos, which do not have the normal weak interactions.' But this could also be an unknown or misunderstood effect. A Los Alamos National Laboratory scientist added that an explanation of this strange anomaly could result in understanding 'matter asymmetry of the universe, or why the universe is primarily composed of matter, rather than antimatter.' The results are published in the Physical Review Letters."
I can't speak for people from a hypothetical universe and about what their naming conventions would be, but I can tell you that, given the known laws, the "anti-matter" universe would behave in exactly the same way as ours does.
No, this isn't true (unless time also runs backwards in the anti-matter universe).
Neutral Kaon decay violates CP - You can distinguish K0 decay in our universe from the anti-K0 decay in an antimatter universe.
It is conjectured that CPT symmetry does hold (therefore CP violation implies T violation)
http://en.wikipedia.org/wiki/CP_violation
Tim.
God said, "div D = rho, div B = 0, curl E = -@B/@t, curl H = J + @D/@t," and there was light.
Since you are a /former) particle physicist, maybe you can explain me why it's not considered entirely natural that there are neutrinos which don't interact with the weak force. My consideration is the following: For each particle except the neutrino there are left-handed and right-handed versions. Only for neutrinos, only left-handed have been observed. Now what would a right-handed neutrino look like? Well, obviously it would not interact strong or electromagnetic, because after all it's a neutrino. But it also wouldn't interact weak, because it's right-handed. This would explain why it wasn't observed in experiments (because AFAIK Neutrinos are always observed through their weak interaction). On the other hand, it would interact gravitationally, and would therefore make a form of dark matter, without any extension to the standard model, except that one would drop the claim that there are only left-handed neutrinos. Since it seems strange anyway that neutrinos, unlike all other particles, only come in left-handed form, I'd expect that a "sterile" right-handed neutrino would be the natural assumption.
However the fact that particle physicists don't assume that, I guess there are good reasons not to assume it. So what is the problem with this reasoning? And could the sterile neutrino from this story be actually such a right-handed neutrino?
The Tao of math: The numbers you can count are not the real numbers.
I would guess that the research is quite solid, the press release is overhyping as usual.
Cosmic Gall, by John Updike
NEUTRINOS, they are very small.
They have no charge and have no mass
And do not interact at all.
The earth is just a silly ball
To them, through which they simply pass,
Like dustmaids down a drafty hall
Or photons through a sheet of glass.
They snub the most exquisite gas,
Ignore the most substantial wall,
Cold shoulder steel and sounding brass,
Insult the stallion in his stall,
And scorning barriers of class,
Infiltrate you and me! Like tall
and painless guillotines, they fall
Down through our heads into the grass.
At night, they enter at Nepal
and pierce the lover and his lass
From underneath the bed-you call
It wonderful; I call it crass.