A new study by Fermilab suggests the elusive Higgs boson may not be one particle. Findings by the DZero experiment at the Tevatron particle accelerator point to the possibility of five Higgs bosons with similar masses but different electric charges.
Finding the Higgs is the primary aim of the £6bn ($10bn) Large Hadron Collider (LHC) experiment near Geneva.
But recent results from the LHC's US rival suggest physicists could be hunting five particles, not one.
The data may point to new laws of physics beyond the current accepted theory - known as the Standard Model.
The Higgs boson's nickname comes from its importance to the Standard Model; it is the sub-atomic particle which explains why all other particles have mass.
However, despite decades trying, no-one, so far, has detected it.