杏吧原创

The Higgs boson is still missing 鈥� but perhaps we should be more worried about what else the Large Hadron Collider hasn鈥檛 found yet.

That鈥檚 the main message to come out of a in Grenoble, France, this week, where physicists have gathered to chew over the first results from the world鈥檚 most muscular particle smasher, sited at CERN near Geneva, Switzerland.

Finding the Higgs would complete the 鈥渟tandard model鈥�, our best stab yet at explaining the fundamental particles and forces of nature. But we already know that some weighty questions, such as the relationship between the strengths of different forces in the cosmos, or the nature of the dark matter thought to make up about three-quarters of its mass, lie beyond the standard model鈥檚 scope. To answer these questions, physicists look to a grander construction known as supersymmetry.

Supersymmetry proposes that every particle predicted by the standard model has a meatier cousin that turns up only at extremely high energies. But the LHC has not found any such super-particles. 鈥淪quarks鈥� and 鈥済luinos鈥�, partners of the standard-model quarks and gluons, have been ruled out at energies up to 1聽teraelectronvolts (TeV), according to an analysis of the LHC鈥檚 first year of collisions.

No simple models

That is just the range in which the simplest family of supersymmetric models predicts these particles should be found. More energies and more complex models remain to be explored, but 鈥渢he air is getting thin for supersymmetry鈥�, says Guido Tonelli of the LHC鈥檚 CMS collaboration. At the same time, there is no sign yet of gravitons 鈥� particles that transmit gravity and are essential for a quantum theory of the force 鈥� below an energy of 2聽TeV.

The missing particles leave some physicists wondering whether they have been asking the right questions up to now. But Rolf-Dieter Heuer, CERN鈥檚 director general, counsels against hasty conclusions. With the machine still ramping up to full power, the LHC has produced just one-thousandth of the data it eventually should deliver. 鈥淪omething will come,鈥� he says. 鈥淲e just have to be patient.鈥�

In the case of the Higgs boson, at least, he鈥檚 confident that something will come sooner rather than later. The LHC has already found the first tantalising glimpses of what might turn out to be this elusive particle, but more findings are needed to confirm or deny its existence. 鈥淲e will have answered the Higgs鈥檚 Shakespeare question 鈥� to be or not to be 鈥� by the end of next year,鈥� Heuer predicts.