Large Hadron Collider's early data shared in Toronto
Physicists probe previously uncharted energies, but find no new particles yet
The Large Hadron Collider in Switzerland began operating on March 27. About 150 physicists gathered this week to share their findings at the annual Hadron Collider Physics Symposium.
In July, researchers reported that by using the LHC, they had rediscovered many particles discovered by earlier particle colliders. Now, however, they've moved beyond that, said Pierre Savard, a University of Toronto physicist and a scientist at TRIUMF, Canada's national laboratory for particle and nuclear physics.
"We've crossed essentially the border where we were just confirming results .… We're really exploring, we're searching for new particles that haven't been looked at before."
Physicists hope to use the powerful tool to uncover nature of the universe and its origins by finding new particles that form the smallest building blocks of all things and recreating the conditions just after the Big Bang.
Savard presented his latest results at a Thursday morning session devoted to the search for particles and forces that aren't part of the Standard Model of Physics. That model has stood for more than three decades and includes all known subatomic particles.
But it is predicted by many theorists to break down at the high energies that are being explored for the first time using the LHC — energies around one teraelectronvolt (TeV), which Savard described as about a million times higher than the energy at the centre of the Sun.
At higher energies, physicists can search for smaller and smaller particles, he added.
The results presented this week are all consistent with the Standard Model, Savard said, but they already show that the Standard Model holds at higher energies than could previously be tested: "It's a very significant milestone for the LHC."
Various theoretical models predict certain particles under certain conditions, which should generate certain signals. Savard and other researchers showed Thursday how they looked for those signals and have not yet found them, even while ramping up to previously uncharted energies. In Savard's case, he and his collaborators failed to find "excited quarks."
1st with results
The results may show no new particles or forces so far, but the fact that there were any results mean that this 21st edition of the annual conference is different from any other.
"For the past 10 to 20 years, all the talks were based on what we think we could see and talks that were on simulations of the detector," Savard said. "But now we're actually showing plots that show how the detector is really working and showing real collision events .… Already, with what he have, we're breaking new ground."
More and more results are expected as the LHC produces more data and ramps up to higher energies.
The conference opened on Monday. Thursday is the last day of experimental results, and researchers are expected to discuss their future scientific plans for the LHC on Friday.