Initial energy density of p+p collisions at the LHC

TL;DR

This paper uses relativistic hydrodynamics to estimate the initial energy density in high-energy proton-proton collisions at the LHC, suggesting conditions that may produce a non-hadronic medium.

Contribution

It provides an advanced estimate of initial energy density in p+p collisions at LHC energies using explicit hydrodynamic solutions, indicating possible formation of a quark-gluon plasma.

Findings

Initial energy density exceeds the critical QCD threshold.

High multiplicity events reach several times the critical energy density.

Conditions suggest the possible creation of a non-hadronic medium.

Abstract

Accelerating, exact, explicit and simple solutions of relativistic hydrodynamics allow for a simple description of highly relativistic p+p collisions. These solutions yield a finite rapidity distribution, thus they lead to an advanced estimate of the initial energy density of high energy collisions. We show that such an advanced estimate yields an initial energy density in $\sqrt{s}=7$ and 8 TeV p+p collisions at LHC around or above the critical energy density from lattice QCD, and a corresponding initial temperature above the critical temperature from QCD and the Hagedorn temperature. We also show, that several times the critical energy density may have been reached in high multiplicity events, hinting at a non-hadronic medium created in high multiplicity $\sqrt{s}=7$ and 8 TeV p+p collisions.