RECENT hints of a featherweight Higgs boson don鈥檛 just take us nearer to a complete standard model of physics. The results affect a possible link between the Higgs and dark matter, the invisible stuff making up 80 per cent of the universe鈥檚 matter.
The Higgs is the last remaining hole in the standard model, the leading theory for how particles and forces interact. On 13 December, physicists at CERN near Geneva, Switzerland, presented data from the Large Hadron Collider suggesting Higgs bosons with a mass of 125 gigaelectronvolts (GeV) were made.
The Higgs is detected by looking for suspicious excesses of particles that it might decay into. Before the recent finding, some theorists had speculated that the Higgs hadn鈥檛 shown up yet because it decayed into two dark matter particles, or WIMPs (weakly interacting massive particles), which would be invisible to the LHC鈥檚 detectors. If that was the case, each WIMP would have to be less than half the mass of the Higgs.
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Now Yann Mambrini of the University of Paris-Sud in Orsay, France, and colleagues point out that the new Higgs results suggest that the particle isn鈥檛 decaying into dark matter. 鈥淭he new discovery would show the Higgs is not invisible,鈥� says Mambrini.
鈥淭he new LHC result suggests that the Higgs boson isn鈥檛 decaying into dark matter鈥�
This needn鈥檛 destroy its connection to dark matter: the two may still be linked via other processes. But as the Higgs would decay into dark matter if it could, the WIMPs must now be heavier than 60聽GeV for the link to survive. That fits with one space-based whiff of dark matter but not three earthbound experiments that claimed to see lightweight WIMPs.
A fourth experiment, called , should resolve the issue. If WIMPS are indeed heavy, in one to two years they should show up there. If they don鈥檛, however, then theorists may have to throw out the Higgs-dark matter conspiracy.
鈥淚f you don鈥檛 find anything, you can say this idea is excluded, which is also an important result,鈥� says Oleg Lebedev of the in Hamburg, Germany.
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