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13th March 2013, 08:47 PM  #1041 
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Farsight has also been vague about what force keeps photons in their orbits. There's nothing in the Standard Model that makes that possible, and any deviations from the Standard Model at the electron's mass scale are very tiny. Check on some of the upper limits for nonSM effects at Particle Data Group some time.
There is a StandardModel photonlike particle that can confine itself, however: the gluon, which can make glueballs. It can do that because at energies around 1 GeV, its selfinteraction is superstrong. However, a glueball state has yet to be unambiguously identified, in part because it acts much like a flavorless meson state. That's a meson with its valence quark and antiquark having the same flavor. In fact, glueballs may mix with flavorless mesons with the same quantum numbers and close masses. 
13th March 2013, 09:49 PM  #1042 
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RÉSONAANCES: When shall we call it Higgs?
Quote:
However, the supersymmetry partners of the elementary fermions are sometimes called "scalar fermions", despite the term being an oxymoron. Also, I've seen the Higgs particle called the BroutEnglertHiggs or BEH particle, honoring Robert Brout, François Englert, and Peter Higgs. We may also add Gerald Guralnik, C.R. Hagen, and Tom Kibble. The BEHGHK particle? But sad to say, Robert Brout died on May 3, 2011, a Moseslike death.  In the rest of his entry, Jester, the Résonaances blogger, mentioned that the Higgs particle being spin 2 would be even more awkward than for spin 0. It would have to have nonrenormalizable interactions, and that requires some new physics around 1 TeV to give it such interactions as a lowenergy limit. Why are there no spin 3/2 or higher fundamental particles in the standard model of particle physics?  Quora (registration required) Physicist David SimmonsDuffin answered, and I'll elaborate on it as appropriate. A spinn particle is described by a field that is a tensor with n indices. One has to be careful to project out the lowerspin modes, and that introduces some awkward features into the particle's "propagator". That's a function that says what its field its like at a point after being created at some other point. One starts getting trouble even for spin 1. In momentum space, the W's propagator is proportional to 1/(p^{2}  m^{2})*(g_{ij}  p_{i}p_{j}/m^{2}) for spacetime indices i,j, metric g, momentum p, and mass m. That makes the W's interactions nonrenormalizable with a breakdown energy scale of about 1 TeV. However, electroweak symmetry breaking has a cure for this problem. Its energy scale gives the massive W a maximum energy; above that, the W is effectively massless. In general, a spinn particle's propagator has momentum dependence O(p^{2n2}). Spin0: O(1/p^{2}), spin1: O(1), etc. This is true for fermions as well as for bosons. For fermions, one treats the spinor part as being like 1/2 a coordinate index. This a spin1/2 particle has behavior O(1/p), a spin3/2 one like O(p), etc. So if a massive particle has a negative power of p in its propagator for high momenta, it is wellbehaved, but not otherwise. It's true that there are numerous bound states with spins >= 1, but their interactions' nonrenormalizability is no problem. That's because they have a maximum energy scale: the energy needed to destroy them. For massless particles, one gets a different problem. Steven Weinberg, in volume 1 of his big tome, considers soft (lowenergy) interactions of particles with different spins. Photons (spin 1) are associated with conservation of electric charge, gravitons (spin 2) with conservation of energymomentum, but higher spins would be even more restrictive, not allowing interactions to happen. A spin3/2 particle would be restricted to interacting like a gravitino, etc. Also, the photon's interactions are renormalizable, and the same is true for nonabelian (selfinteracting) gauge fields like the gluon. But the graviton's interactions are not, with the maximum energy scale being the Planck mass. 
14th March 2013, 01:34 AM  #1043 
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RÉSONAANCES: Higgs: what have we learned
Some of it repeats what I'd posted on earlier  rough agreement with the Standard Model's predictions for (H>toptop) * (H>WW), (H>ZZ), (H>tautau) About measuring the Higgs particle's spin, Jester was sure that it had to be 0, but he noted that the spin fits also constrain additional interactions with the W and Z particles. So far, this particle does not have any big differences from the Standard Model there also. He also mentioned constraints on Higgs > Zphoton, mumu, and invisible. These could provide constraints on new physics, since from the Standard Model, they are still too small too see. 
14th March 2013, 04:02 AM  #1044 
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14th March 2013, 04:47 AM  #1045 
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New results indicate that new particle is a Higgs boson  CERN  the likely source of that AP article.
Rencontres de Moriond  the Moriond conference that the article refers to. Very technical, but I can understand much of it. ATLAS Experiment  Photos  includes animations of the Higgsparticle bumps emerging with the collection of more data. 
14th March 2013, 05:02 PM  #1046 
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That is basically because the papers that he relies on are equally vague about this. They evoke magic, e.g. In Is the electron a photon with toroidal topology? the photon is in a "selfcontained" state that forces photons to exhibit "toroidal topology".
We already know that this speculation is invalid because no matter what topology they come up with, a photon can never be a source of charge. Of course the other big problem is they have no mechanism to prevent every photon turning into an electron ! 
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Real Science: NASA Finds Direct Proof of Dark Matter (another observation) (and Abell 520) "Our Undiscovered Universe" by Terence Witt: Review 1; Review 2 

14th March 2013, 09:12 PM  #1047 
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Moriond QCD 2013 Agenda has "Measurements of Higgs Boson Properties in ATLAS" with these upper limits:
Ratio is to StandardModel rate Higgs > muonantimuon: ratio < 9.8 Higgs > Zphoton: ratio < 18.2 If they get enough events to be able to see these modes, they will get enough to see bottomantibottom and likely also charmanticharm. So we'll get the Higgs particle's interactions with the W, Z, top, bottom, tau, charm, muon  plenty of testing of the massproportionality hypothesis. Assuming StandardModel values of all the couplings, the branching fraction to invisible particles they find to be less than 0.6. Also in that presentation was cross sections in picobarns for different production processes, calculated with the Standard Model and a Higgs mass of 125 GeV: 19.5 pb  gluon fusion: 2 gluons  topantitop  H 1.6 pb  vector boson fusion: 2 quarks > each one radiates a W or Z > WW or ZZ > H 1.1 pb  quarkantiquark > W,Z > radiates a H 0.1 pb  2 gluons > each one makes topantitop > one topantitop makes a H So the W and Z rates combined are about 1/8 of the total, the rest being almost entirely top quark. The bottomquark rate is about 1500 times less, and the other quarks' rates even less. For spin2 tests, they are using gravitonlike interactions. That's good for positive parity, but they'd have to modify that for mixed or negative parity. BTW, they are also doing mixedparity tests for spin 0, and so far, the mixture is consistent with being allpositive. They are doing spin and parity tests mainly with H > ZZ, and to a lesser extent with H > WW. But they might eventually extend that to elementary fermions, though they'd have to use mainly H > topantitop. 
14th March 2013, 09:44 PM  #1048 
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20th March 2013, 12:27 PM  #1049 
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RÉSONAANCES: Higgs: more of the same
reporting on Review of the Higgsto2Photon Data  Of Particular Significance Rate / (StandardModel prediction) ATLAS: 1.65 + 0.30 CMS: 0.8 + 0.3 Naive combination: 1.2 + 0.2 So it looks like that's close to the Standard Model also. It also means that the coupling of the Higgs particle to the elementary fermions, or at least to the top quark, is not opposite in sign from what the Standard Model predicts. 
21st March 2013, 08:24 AM  #1050 
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Is it true that the mass of the Higgs boson means that the universe has a halflife?
http://www.escapistmagazine.com/news...WholeUniverse I actually like this scenario better than heat death. A quick, painless end (probably a long time in the future) seems more merciful than any of the other possible ends of the universe I've heard about. 
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“Some men are born mediocre, some men achieve mediocrity, and some men have mediocrity thrust upon them. With Major Major it had been all three.” ― Joseph Heller, Catch22 

21st March 2013, 01:42 PM  #1051 
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Vacuum instability is entirely speculative to begin with; the statement that a 125 GeV Higgs predicts vacuum instability is, I think, extremely hypothetical and/or premature. Lykken is quoted (after giving a talk; he has not published any papers or preprints on this topic) as saying he "thinks" the idea is "gaining traction", which is a very, very soft claim.

21st March 2013, 02:33 PM  #1052 
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RÉSONAANCES: What's the deal with vacuum stability? has a good discussion of this question, complete with this disclaimer:
Quote:
Summary: the Standard Model gets stability problems at an energy scale of about 10^{10} GeV. Using the (rather small) experimental limits on the mass of the top quark and the strength of the QCD interaction, the stability problems set in at about 10^{8} GeV to 10^{14} GeV. To see why this happens, I'll explain how the Higgsparticle field behaves. I'll simplify it from a complex doublet to a real singlet, though the realsinglet field value will act like the magnitude of the full value. The Higgs potential is (1/2)*V2*F^{2} + (1/4)*V4*F^{4} for Higgs field F and parameters V2 and V4. The Higgsfield equation of motion is, in this approximation, D^{2}F + dV/dF = 0 D^{2} = d^{2}/dt^{2}  D^{space}^{2} I'll ignore the spatial variation and focus on the time variation, giving us d^{2}F/dt^{2} + dV/dF = 0 Let's now see how the field behaves. We can carry over techniques from classical mechanics: look for fixed points and see how the field behaves around those points. Does it oscillate around the point? Does it move away from the point? Using dV/dF = F*(V2 + V4*F^{2}) there's an obvious fixed point: F = 0. Oscillations around it behave as dF = dF0*exp(i*w*t) + complex conjugate, where w is the angular frequency of oscillation. It is w = sqrt(V2) If V2*V4 < 0, there is another fixed point, F = sqrt(V2/V4). Its oscillation angular frequency is w = sqrt(2V2) If the angular frequency is real, then the point is stable. Otherwise, it is unstable, with exponential departure. The Higgs mechanism works by having V2 < 0 and V4 > 0, making a stable nonzero fixed point F = sqrt(V2/V4). It has the lowest energy that the field can have, thus making it the ground state. It's that nonzero value of F that gives other StandardModel particles their masses. But if one extrapolates to energy scales above the electroweak one, V2 becomes positive and the Higgs mechanism no longer works. Of the StandardModel particles, only the Higgs one is then massive. The stable fixed point is for F = 0 in this case, what one normally expects of a spin0 particle. The interesting thing here is what happens to V4, often written lambda. It's a measure of the Higgs particle's selfinteraction, and in the bare Standard Model, it becomes negative at energies of 10^{8} GeV  10^{10} GeV  10^{14} GeV. But for the Universe to selfdestruct by Higgs instability, the Higgs field must quantum tunnel from near 0 to near sqrt(V2/V4), and the rate of that tunneling is ~ exp(1/V4). So if V4 is not much less than 0, our Universe is metastable, with a Higgsdecay lifetime longer than its age. 
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