Big to Small...

The cosmos can be considered as a collider for human to access the results of particle physics experiments at ultimate high energies. Credit: Department of Physics, HKUST

Topics: Cosmology, Particle Physics, Standard Model, Theoretical Physics

Our observable universe is the largest object that physicists study: It spans a diameter of almost 100 billion light years. The density correlations in our universe, for example, correlations between numbers of galaxies at different parts of the universe, indicate that our vast universe has originated from a stage of cosmic inflation.

On the other hand, elementary particles are the smallest object that physicists study. A particle physics Standard Model (SM) was established 50 years ago, describing all known particles and their interactions.

Are density distributions of the vast universe and the nature of smallest particles related? In a recent research, scientists from HKUST and Harvard University revealed the connection between those two aspects, and argued that our universe could be used as a particle physics "collider" to study the high energy particle physics. Their findings mark the first step of cosmological collider phenomenology and pave the way for future discovery of new physics unknown yet to mankind.

The research was published in the journal Physical Review Letters on June 29, 2017 and the preprint is available online.

"Ongoing observations of cosmological microwave background and large scale structures have achieved impressive precision, from which valuable information about primordial density perturbations can be extracted, " said Yi Wang, a co-author of the paper and an assistant professor at HKUST's department of physics. "A careful study of this SM background would be the prerequisite for using the cosmological collider to explore any new physics, and any observational signal that deviates from this background would then be a sign of physics beyond the SM."

Scientist reveal new connections between small particles and the vast universe, Xingang Chen et al, Standard Model Background of the Cosmological Collider, Physical Review Letters (2017). DOI: 10.1103/PhysRevLett.118.261302 , On Arxiv: https://arxiv.org/abs/1610.06597, Phys.org