The Large Hadron Collider Returns in the Hunt for New Physics

Desperately seeking SUSY.

In 2012, researchers at the world's largest particle accelerator announced they had discovered a particle that resembled a key missing piece in our fundamental understanding of physics: the Higgs boson.

It was a Nobel Prize-worthy moment. But what comes next could be even more exciting.

The Large Hadron Collider is back for its second run at almost twice the energy it had then. This time, it's hoped it could shed light on physics beyond the Standard Model, the decades-old theory that describes the fundamental particles and forces that make up our universe.

"By moving up in energy, we open this window on producing these heavier, more exciting particles that we've never seen before," Chris Young, who works on the ATLAS experiment, explained when we visited the site.

At 27km in circumference, the LHC spans the border of France and Switzerland near Geneva. After two years of maintenance, it was recently rebooted with proton beams primed to collide at an energy of 13 TeV (teraelectronvolts). The last run, when the Higgs was discovered, got to a maximum of 8 TeV.

The increased energy means there's scope to find particles we haven't seen before, and some physicists have their eyes open for evidence of one particular extension to the Standard Model: supersymmetry.

Known fondly by proponents as SUSY, this set of theories suggests that every Standard Model particle has a supersymmetric partner; each particle is partnered with a "sparticle."

Supersymmetry is a compelling idea. It could conveniently fill in some of the remaining gaps in the Standard Model, such as the mass of the Higgs boson. "Supersymmetry would be one way of avoiding the future collapse of the universe," theoretical physicist John Ellis, a major proponent of SUSY, told us.

And it could delve further into the mysteries of our universe: One of the theorised supersymmetric particles, the neutralino, is a candidate for dark matter.

But as attractive as it all sounds, there's a caveat: We haven't yet found any supersymmetric particles.

With the LHC's new, higher energies, it's the best chance yet to detect something supersymmetric and add experimental backing to a theory that some theoretical physicists have dedicated their life's work to.

Just as the LHC was booting up for its new run, we visited CERN to check up on one of the largest experimental science facilities ever built. We spoke to the people running this huge machine and gathering data from the unprecedented particle collisions, as well as the theoretical physicists waiting for experimental data to settle their rivalries once and for all.

"This year is the hundred-year anniversary of Einstein's theory of general relativity, which revolutionised our ideas about space and time and gravity," Ellis said. "I think the discovery of supersymmetry would be as big as that—something beyond what Einstein could ever dream of."