LHC reveals hints of new physics in particle decays

The LHCb detector was designed to examine particles called mesons, watching them decay through time after high-energy collisions of other fundamental particles.

The LHCb Collaboration was looking at decays of particles called D-mesons, which can in turn decay into kaons and pions.

LHCb, one of the six separate experiments at the Large Hadron Collider, is particularly suited for examining what is called "CP violation" – slight differences in behaviour if a given particle is swapped for its antimatter counterpart.

Our best understanding of physics so far, called the Standard Model, suggests that the complicated cascades of decay of matter particles into other particles should be very nearly the same – within less than 0.1% – as a similar chain of antimatter decays.

Other experiments, notably at the Fermi National Accelerator facility in the US, have found a CP violation of about 0.1%, but with an uncertainty in their measurement that meant the result might just fit within the Standard Model.

But the LHCb team is reporting a difference of about 0.8% – a significant difference that, if true, could herald the first "new physics" to be found at the LHC.

"Our result is more significant firstly because it comes out with a [greater difference] and secondly because our precision is improved – somewhat more precise than all of the previous results put together," Dr Charles told BBC News.

Spotting such a difference in the behaviour of matter and antimatter particles may also finally help explain why our Universe is overwhelmingly made of matter.

"Certainly this kind of effect, a new source of CP violation, could be a manifestation of the physics which drives the matter – antimatter asymmetry," Dr Charles explained.

However, he stressed there are "many steps in the chain" between confirming the collaboration’s experimental result, and resolving the theory to accommodate it.

"This result is a hint of something interesting and if it bears out, it will mean that, at a minimum, our current theoretical understanding needs improving," Dr Charles said.

"It’s exactly the sort of thing for which the LHC was originally built."

vía BBC News – LHC reveals hints of ‘new physics’ in particle decays.