Study reveals new details on what happened in the first microsecond of Big Bang

[beecee]

https://phys.org/news/2021-05-reveals-microsecond-big.html

MAY 21, 2021

Study reveals new details on what happened in the first microsecond of Big Bang:

Researchers from University of Copenhagen have investigated what happened to a specific kind of plasma—the first matter ever to be present—during the first microsecond of Big Bang. Their findings provide a piece of the puzzle to the evolution of the universe, as we know it today.

 

About 14 billion years ago, our universe changed from being a lot hotter and denser to expanding radically—a process that scientists have named the Big Bang.

And even though we know that this fast expansion created particles, atoms, stars, galaxies and life as we know it today, the details of how it all happened are still unknown.

Now a new study performed by researchers from University of Copenhagen reveals insights on how it all began.

"We have studied a substance called Quark-Gluon Plasma that was the only matter, which existed during the first microsecond of Big Bang. Our results tell us a unique story of how the plasma evolved in the early stage of the universe," explains You Zhou, Associate Professor at the Niels Bohr Institute, University of Copenhagen.

"First the plasma that consisted of quarks and gluons was separated by the hot expansion of the universe. Then the pieces of quark reformed into so-called hadrons. A hadron with three quarks makes a proton, which is part of atomic cores. These cores are the building blocks that constitutes earth, ourselves and the universe that surrounds us," he adds.

more at link..............

 

the paper:

https://www.sciencedirect.com/science/article/pii/S037026932100294X?via%3Dihub

Measurements of mixed harmonic cumulants in Pb–Pb collisions at sNN=5.02 TeV

 

 

Abstract:

Correlations between moments of different flow coefficients are measured in Pb–Pb collisions at sNN=5.02 TeV recorded with the ALICE detector. These new measurements are based on multiparticle mixed harmonic cumulants calculated using charged particles in the pseudorapidity region |η|<0.8 with the transverse momentum range 0.2<pT<5.0 GeV/c. The centrality dependence of correlations between two flow coefficients as well as the correlations between three flow coefficients, both in terms of their second moments, are shown. In addition, a collection of mixed harmonic cumulants involving higher moments of v2 and v3 is measured for the first time, where the characteristic signature of negative, positive and negative signs of four-, six- and eight-particle cumulants are observed, respectively. The measurements are compared to the hydrodynamic calculations using iEBE-VISHNU with AMPT and TRENTo initial conditions. It is shown that the measurements carried out using the LHC Run 2 data in 2015 have the precision to explore the details of initial-state fluctuations and probe the nonlinear hydrodynamic response of v2 and v3 to their corresponding initial anisotropy coefficients ε2 and ε3. These new studies on correlations between three flow coefficients as well as correlations between higher moments of two different flow coefficients will pave the way to tighten constraints on initial-state models and help to extract precise information on the dynamic evolution of the hot and dense matter created in heavy-ion collisions at the LHC.