Higgs Boson may unravel dark energy mystery

The recently discovered Higgs boson could provide a possible "portal" to physics that may help explain some of the attributes of the enigmatic dark energy, scientists suggest.

One of the biggest mysteries in contemporary particle physics and cosmology is why dark energy, which is observed to dominate energy density of the universe, has a remarkably small (but not zero) value, researchers said.

This value is so small, it is perhaps 120 orders of magnitude less than would be expected based on fundamental physics, they said.

Now, physicists – Lawrence Krauss of Arizona State University and James Dent of the University of Louisiana-Lafayette - explore how a possible small coupling between the Higgs particle, and possible new particles likely to be associated with what is conventionally called the Grand Unified Scale could result in the existence of another background field in nature in addition to the Higgs field.

This would contribute an energy density to empty space of precisely the correct scale to correspond to the observed energy density, researchers said.

Current observations of the universe show it is expanding at an accelerated rate. But this acceleration cannot be accounted for on the basis of matter alone, they said.

Putting energy in empty space produces a repulsive gravitational force opposing the attractive force produced by matter, including the dark matter that is inferred to dominate the mass of essentially all galaxies, but which doesn't interact directly with light and, therefore, can only be estimated by its gravitational influence.

Because of this phenomenon and what is observed in the universe, it is thought that such 'dark energy' contributes up to 70 per cent of the total energy density in the universe, while observable matter contributes only 2 to 5 per cent, with the remaining 25 per cent or so coming from dark matter.

The source of this dark energy and the reason its magnitude matches the inferred magnitude of the energy in empty space is not currently understood, making it one of the leading outstanding problems in particle physics today.

"Now that the Higgs boson has been discovered, it provides a possible 'portal' to physics at much higher energy scales through very small possible mixings and couplings to new scalar fields which may operate at these scales," said Krauss.

"We demonstrate that the simplest small mixing, related to the ratios of the scale at which electroweak physics operates, and a possible Grand Unified Scale, produces a possible contribution to the vacuum energy today of precisely the correct order of magnitude to account for the observed dark energy," Krauss said. The study was published in the journal Physical Review Letters.