Nature News | 20 July 2010
13th International Conference on Elastic and Diffractive Scattering (Blois Workshop) - Moving Forward into the LHC EraThe Large Hadron Collider could throw up evidence of new physics earlier than expected.
As if the Large Hadron Collider (LHC) didn't have enough to look for. It is already charged with hunting for the fabled Higgs boson, extra dimensions and supersymmetry, but physicists are now adding even more elaborate phenomena to its shopping list — including vanishing dimensions that could explain the accelerating expansion of the Universe. Some argue that signs of new and exotic physics could show up in the LHC far sooner than expected.
In March, the LHC, sited at CERN, Europe's particle-physics facility near Geneva, Switzerland, began colliding protons at energies of 7 trillion electronvolts — half the final target but already three times greater than its nearest rival, the Tevatron in Batavia, Illinois. This week, particle physicists gather at the International Conference on High Energy Physics (ICHEP) in Paris to discuss what they hope to find — and when the discoveries might emerge.
Still topping physicists' wish lists is the Higgs boson, the elusive particle thought to be part of the mechanism that gives other particles their mass. If the standard model of particle physics has correctly predicted its characteristics, gathering enough data to find the Higgs should take about two more years, says Albert de Roeck, deputy spokesman for the Compact Muon Solenoid (CMS) experiment at the LHC.
But beyond the Higgs, researchers hope to see evidence of new physics. So far, accelerator experiments have repeatedly confirmed the predictions of the standard model, which encompasses all discovered particles, the Higgs and three of the fundamental forces of nature: electromagnetism; the weak force that controls radioactivity; and the strong force that binds quarks together. "It's annoying, because from a mathematical perspective, we know that the standard model must be wrong," says Greg Landsberg, a particle physicist at Brown University in Providence, Rhode Island. The model breaks down at high energies (such as those predicted in the early Universe), giving infinite answers for the strength of particle interactions, unless physicists fudge the numbers.
One addendum to the standard model that does away with this fine-tuning is supersymmetry (SUSY), which posits the existence of heavier twins for all known particles. These SUSY twins could show up at the LHC within a couple of years, says de Roeck.
The other big prize for the LHC would be evidence of extra dimensions. These are proposed by some forms of string theory, which describes the fundamental building blocks of the Universe as endlessly vibrating strands. If extra dimensions exist, their presence could show up as a shortfall in the energy of collision debris, indicating that some particles created in the smash can access these dimensions. Miniature black holes appearing during collisions could also betray the gravitational effects of these dimensions, de Roeck says.
The accelerator has already hit the high energies needed for these new particles and exotic effects to pop up. But the machine needs to ramp up its collision rate to generate enough data to prove that rare anomalies are more than statistical blips, says de Roeck.
- arXiv.org > hep-ph > arXiv:1002.3527 > 17 Feb 2010
Proceedings of the 13th International Conference on Elastic and Diffractive Scattering, CERN, Geneva, June-July 2009
I didn't catch that. In Nature, yet.