Researchers at Ecole Polytechnique Fédérale de Lausanne are hoping the Higgs boson is found at the LHC for a big reason - they think it can explain universal expansion and even reveal the possible existence of another closely related particle.

The Higgs boson would help explain why the majority of elementary particles possess mass. but a group of EPFL physicists say it would also help us understand the evolution of the Universe from the moment of its birth - and it could be verified with data from the Planck satellite.

The Universe was incredibly minuscule at its birth but it is unimaginably large now. To explain this dichotomy of scale and that matter is seemingly distributed in a homogeneous fashion throughout the Universe, theoretical physicists added an inflationary phase to the Big Bang, an initial phenomenal expansion in which the Universe grew by a factor of 10^26 in a short time.  Short speaking in universal terms, of course, not like a bomb going off. 

If the Universe was unimaginably dense, why wouldn't gravity have slowed down its initial expansion? The Higgs boson can explain the speed and magnitude of the expansion, says Mikhail Shaposhnikov and a team from EPFL's Laboratory of Particle Physics and Cosmology. In this infant Universe, the Higgs, in a condensate phase, would have behaved in a very special way – and in so doing changed the laws of physics. The force of gravity would have been reduced. It sounds like magic, but they say that is how physicists can explain how the Universe expanded at such an incredible rate.

Their idea may clear up the first moments of the Universe, but what about the Universe as it is today? "We have determined that when the Higgs condensate disappeared to make way for the particles that exist today, the equations permitted the existence of a new, massless particle, the dilaton," says EPFL physicist Daniel Zenhäusern.

 The Higgs boson may also play a role in the Big Bang theory. Credit: EPFL

How did they come up with all that?  Scale invariance. Starting with the existence of a Higgs boson, they inferred the existence of the dilaton, a close cousin, as well as its properties. This new and as yet purely hypothetical particle happens to have the exact characteristics to explain the existence of dark energy. Dark energy explains why the expansion of the current Universe is once again accelerating, but its origins are not understood.

Astrophysicists are measuring the state of the Universe today using data from the Planck satellite. They are observing the light echo from the Big Bang, which reveals the large scale properties of the cosmos. In 2013, the measurement campaign will provide results that will be precise enough to compare with the EPFL predictions – and they'll be able to see if their Higgs theory holds up. The boson isn't just hidden in the bowels of CERN's accelerator.

Citation: Higgs-Dilaton Cosmology: From the Early to the Late Universe, Juan García-Bellido, Javier Rubio, Mikhail Shaposhnikov, Daniel Zenhäusern, High Energy Physics - Phenomenology  http://arxiv.org/abs/1107.2163