Question

The WIKI Higgs boson site has an interesting diagram illustrating likely Higgs mass intervals that experiments (LEP & Tevatron) or indirect measurements have determined with a 95% confidence level. It posits that the feasible mass ranges are in the intervals of about 115-158 GeV or 175-185 GeV. The Tevatron confirmed the existance of the top quark (172 GeV) in 1995, so it had the energy and time to detect the Higgs in the 115-158 GeV ranges, but could not. Given LHC's greater energy and luminosity, why haven't there been anouncements of the Higgs discovery? Do we understand enough about potential particle creation to definitively know they are Higgs decays?

Answer 1

There are two considerations:

a) if you follow a bit the current theories, the manifestation of the Higgs decays can vary, depending on the parameters of the models, and there are many models.

b) Hadron colliders, in contrast to e+e- ones are "dirty", there are enormous backgrounds that have to be understood, and the few clear decay channels proposed by theories have small crossections and have to be fished out of these backgrounds. So more data than the ones existing are necessary to be able to answer definitively the Higgs question.

LHC is now building up the statistics necessary.

So what I foresee will happen, if we are lucky, is first a new resonance in some of the channels checked will be declared with at least 4 sigma. Then everybody will fall on it, experimentalists to find other decay channels and theorists to fit specific models to decide whether it is the Higgs or not.