Saturday, 31 December 2011

LHC Higgs Boson 125 GeV, and not standard model

On December the 13th 2011, the LHC released the first ever figures showing a Higgs Boson. This the particle (or set of particles) which give rise the mass of all the elementary particles in the universe. The signal was only around 3 sigma, after 5 femtobarnes of collisions, and woundn't ordinarily have been reguards has a proof of exists of the particle, except for the fact the physicists where already so sure that a Higgs Boson does exist. But the Higgs Boson they found does look like one from either the standard model or supersymmetry. The branching ratios for the different decays are different from the predicted values. According to the theory, the rate of the Higgs decay to a particular particle should be proportional to the mass of that particle. Instead CMS found

$$ σ(H) x {B(H → bb)} / {σ(B_{sm})} ∼ 0.5 $$
$$ σ(H) x {B(H → ττ)} / {σ(B_{sm})} ∼ 1 $$
$$ σ(H) x {B(H → γγ)} / {σ(B_{sm})} ∼ 1.7 $$
$$ σ(H) x {B(H → WW)} / {σ(B_{sm})} ∼ 0.6 $$
$$ σ(H) x {B(H → ZZ)} / {σ(B_{sm})} ∼ 0.5 $$

A factor of a half to the electroweak bosons, and ordinary quarks. About 1.7 for electromagnetic radiation and the standard factor for leptons. If you look back at Axitronics you'll find we quoted a prediction for a mirror-matter Higgs from Robert Foot, for the Mirror-Matter model, that predicted a factor of a half for Higg Boson branches across the board. Well the data we got is similar to that for more complicated, can we find a model to fit it. In fact the data, seems to match my E6 model. Which has as well as 15 particles of the standard model, and additional 12 vector-like quarks in the group.

The number of Leptons is the same so tau figures are identical. This Higgs would decay equally to either the quarks in the 12 or the 15 of E6, so the figure for bottom quarks would be half. There would be an additional W and Z just for the decays to the vector like 12 of E6, so again this figure would be a half. Finally the photonic decays (found by summing the squares of the charges of any pair of particles a Higgs could produce which then annihilate to a pair of photons is.

$$γγ = 3 generations * ( ee + 3 colors * [ dd +uu + DD+ UU])$$
$$B(γγ) = 3 + 9 * (1/9 + 4/9) = 8 [Standard Model] $$
$$B(γγ) = 3 + 9 * (2/9 + 8/9) = 13 [E6 (12+15)] $$

So $$B(γγ) = 1.625$$ Very close the observed figure. Including the normal W its 14/9 or 1.555. Finally if (and we expect one) there's any extra leptophobic right handed W and Z in E6, that will change to 1.666, the closest to the CMS figure.

During 2012, the amount of data with triple, and the mass and branching ratios will get much more accurately. The cross-section compared with the standard model will be known, and we might start seeing invisible decays to mirror matter or SUSY particles, so a deeply interesting year to come for particle physics. The Higgs Boson for a model with additional vector like quarks has been looked at byChacko et al, and would mean SUSY is unnecessary for stabilizing the Higgs Boson mass all the way up to 5+ TeV, so SUSY might well not be found in the 7TeV LHC runs.

Finally the Higgs might be composite, in fact if the color interaction between normal and vector-like quarks, is double the strength of the normal interaction, then these combinations have the right sort of energies for technicolor stuff composites to make up the Higgs.

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