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 the 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 the QGP formation, which made these studies quite stimulating as to how the collision of small systems features in producing the early universe signals. In this article, we report on some of the compelling experimental results and give an account of the present understanding. We review the pp physics program at the LHC and discuss future prospects in the context of exploring the nature of the primordial matter in the early universe.

Systematic analysis of the pp collisions at LHC energies with Tsallis function

“…As stated above, QGP has been discovered in a nucleusnucleus collision, and many signatures relevant to such a state of matter have also been observed in small systems like pp collisions. Some of the observed signatures in high-multiplicity pp events include strangeness enhancement [19], production of a large number of particles [20], equivalent effective temperature, kinetic freezeout temperature, and flow velocity to those obtained in nucleus-nucleus collisions [21,22] and multiparticle ridgelike correlations [23]. pp collisions are the baseline for studying AA or pA collisions.…”