Physicists at the Large Hadron Collider (LHC) in Europe have explored the properties of nature at higher energies than ever before, and they have found something profound: nothing new.
It’s perhaps the one thing that no one predicted 30 years ago when the project was first conceived.
The infamous “diphoton bump” that arose in data plots in December has disappeared, indicating that it was a fleeting statistical fluctuation rather than a revolutionary new fundamental particle. And in fact, the machine’s collisions have so far conjured up no particles at all beyond those catalogued in the long-reigning but incomplete “Standard Model” of particle physics. In the collision debris, physicists have found no particles that could comprise dark matter, no siblings or cousins of the Higgs boson, no sign of extra dimensions, no leptoquarks—and above all, none of the desperately sought supersymmetry particles that would round out equations and satisfy “naturalness,” a deep principle about how the laws of nature ought to work.
“It’s striking that we’ve thought about these things for 30 years and we have not made one correct prediction that they have seen,” said Nima Arkani-Hamed, a professor of physics at the Institute for Advanced Study in Princeton, N.J.
The news has emerged at the International Conference on High Energy Physics in Chicago over the past few days in presentations by the ATLAS and CMS experiments, whose cathedral-like detectors sit at 6 and 12 o’clock on the LHC’s 17-mile ring. Both teams, each with over 3,000 members, have been working feverishly for the past three months analyzing a glut of data from a machine that is finally running at full throttle after being upgraded to nearly double its previous operating energy. It now collides protons with 13 trillion electron volts (TeV) of energy—more than 13,000 times the protons’ individual masses—providing enough raw material to beget gargantuan elementary particles, should any exist.