Possible early universe signals in proton collisions at the Large Hadron Collider

Abstract

Our universe was born about 13.8 billion years ago from an extremely hot and dense singular point, in a process known as the Big Bang. The hot and dense matter which dominated the system within a few microseconds of its birth was in the form of a soup of elementary quarks and gluons, known as the quark–gluon plasma (QGP). Signatures compatible with the formation of QGP matter have experimentally been observed in heavy-ion (such as Au or Pb) collisions at ultra-relativistic energies. Recently, experimental data of proton–proton (pp) collisions at the CERN Large Hadron Collider (LHC) have also shown signals resembling those of QGP formation, which made these studies stimulating as to how the collision of small systems features in producing the early universe signals. In this article, we discuss some of the compelling experimental results and give an account of the present understanding. We review the pp physics programme at the LHC and discuss future prospects in the context of exploring the nature of primordial matter in the early universe. © 2021. All Rights Reserved.