Tuesday, January 23, 2007

MSSM Higgs at 160 GeV: 2.1 sigma signal

An acausal update: John Conway whom I know from Rutgers University and whose favorite particle is the tau lepton has two long articles about the bump at CosmicVariance: first, second. Holy crap. Or not?

Can we prove the minimal supersymmetric model (MSSM, Dine's book chapter 11), the next layer of string theory's predictions about reality, experimentally?

The Higgs sector contains 8-3=5 particles (instead of 4-3=1 God particle - also named Weinberg's toilet by Sheldon Glashow - in the normal Standard Model) because there must be two Higgs doublets in order to allow masses both for the upper quarks and the lower quarks. One of the recent Run II preliminary charts of the D0 detector group is the following:

Figure 1: The decay of the Z boson according to the D0 group

So is there a Higgs boson? The answer partially depends on the question whether there is a bump in the figure above. It would be great if a readers who are good at looking at pictures tried to answer whether there is a bump in this picture. Don't be fooled: the yellow curve is an idealization. The real data are the white circles with the vertical lines representing the error bars. ;-)

Most readers will say "Of course there is a bump". Unfortunately, the bump around 80 GeV is not a Higgs. It is the Z boson. If they see a Higgs, it is a bump around 160 GeV which is much less convincing. Still, you should know that a similar measurement of CDF sees a 2.1 signal for the A Higgs of the MSSM - it can't be interpreted as a non-supersymmetric Higgs boson - which is higher than the 1.7 sigma signal for the 115 GeV Higgs that we see at the end of the life of LEP.

I am unconvinced by the statement that there is an extra bump at 160 GeV in the chart above. The chart would be more likely to indicate a bump at 140 GeV. Stay tuned.

Via Dorigo where you find other data such as a weak excess of some events measured at CDF that could indicate the MSSM Higgs around 160 GeV. CDF will release its version of the figure above in the middle of February.

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