Has new ghost particle manifested at Large Hadron Collider?

‘Something terribly new’ goes bump in data yet to be confirmed by Atlas detector

Xenon-Xenon collision in the CMS detector at the CERN Large Hadron Collider
Scientists at the Cern nuclear physics lab near Geneva are investigating whether a bizarre and unexpected new particle popped into existence during experiments at the Large Hadron Collider.

Researchers on the machine’s multipurpose Compact Muon Solenoid (CMS) detector have spotted curious bumps in their data that may be the calling card of an unknown particle that has more than twice the mass of a carbon atom.

The prospect of such a mysterious particle has baffled physicists as much as it has excited them. At the moment, none of their favoured theories of reality include the particle, though many theorists are now hard at work on models that do.

“I’d say theorists are excited and experimentalists are very sceptical,” said Alexandre Nikitenko, a theorist on the CMS team who worked on the data. “As a physicist I must be very critical, but as the author of this analysis I must have some optimism too.”

Senior scientists at the lab have scheduled a talk this Thursday at which Nikitenko and his colleague Yotam Soreq will discuss the work. They will describe how they spotted the bumps in CMS data while searching for evidence of a lighter cousin of the Higgs boson, the elusive particle that was discovered at the LHC in 2012.

The Large Hadron Collider creates particles by smashing subatomic protons into one another at close to the speed of light. When the protons meet, the energy in the collision is converted into mass, and so particles, in line with Einstein’s equation, E=mc2.

Many particles created in the LHC are highly unstable and immediately decay into lighter, more stable particles such as photons and electrons. It is by looking for an excess of these particles, apparent as a bump in the data, that physicists tend to find new particles. For example, one way the Higgs boson betrayed its existence was through the unusually high number of photons recorded in collisions in which the particle was made.


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