The Large Hadron Collider is by no means the last of the particle smashers. A group at CERN recently explored the various scenarios that might emerge from the atomic debris in Geneva – and how they would shape what colliders we build next. We draw out the key points about each of the scenarios.

Moving on (Image: CERN)
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Detect a Higgs

What will detecting a Higgs boson mean?

If the characteristics of the Higgs fit with the predictions of the standard model of particle physics, it should be found within three years. The discovery would confirm that a Higgs "field" permeates the universe, lending all other particles their mass. If it is a Higgs that does not conform to the standard model, it may turn up even earlier, because it would likely be lighter and so more commonly produced in collisions than heavier particles.

What next?                   

The Super LHC will have more collisions per second and be more accurate than the LHC, and would be able to start to explore the properties of a Higgs. Its high energy would be especially useful if the Higgs turns out to be heavy, though a linear collider would be more precise. The Compact Linear Collider would have an advantage over the International Linear Collider with its higher collision energy.

No Higgs

What will failing to detect a Higgs mean?

If no Higgs is detected after three years of the LHC running at full energy, then this points to a more complicated Higgs field. It could be because the Higgs decays to known particles that are difficult to detect at the LHC or it decays to invisible particles – ones that don't interact with the detector.

Failure could also be a sign of a non-standard model Higgs – which would mean it could be lighter or heavier than expected and thus harder to find. Or it could indicate a more exotic Higgs field – perhaps with several different Higgs bosons interacting in a way not yet fully understood.

What next?                   

Other mechanisms for endowing particles with mass will be seriously considered. For example, when two W bosons collide, they are thought to produce a Higgs. If no Higgs exists, however, whatever else is produced by W boson scattering would be the obvious next place to look for what endows matter with mass. The process could be examined extensively with the Super LHC.

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