An international team of scientists has published a new report that moves towards a better understanding of the behaviour of some of the heaviest particles in the universe under extreme conditions, which are similar to those just after the big bang. The paper, published in the journal Physics Reports , is signed by physicists Juan M. Torres Rincón, from the Institute of Cosmos Sciences at the University of Barcelona (ICCUB), Santosh K. Das, from the Indian Institute of Technology Goa (India), and Ralf Rapp, from Texas A&M University (United States).
The authors have published a comprehensive review that explores how particles containing heavy quarks (known as charm and bottom hadrons) interact in a hot, dense environment called hadronic matter. This environment is created in the last phase of high-energy collisions of atomic nuclei, such as those taking place at the Large Hadron Collider (LHC) and the Relativistic Heavy Ion Collider (RHIC). The new study highlights the importance of including hadronic interactions in simulations to accurately interpret data from experiments at these large scientific infrastructures.
The study broadens the perspective on how matter behaves under extreme conditions and helps to solve some great unknowns about the origin of the universe.
Reproducing the primordial universe
When two atomic nuclei collide at near-light speeds, they generate temperatures more than a 1,000 times higher than those at the centre of the Sun. These collisions briefly produce a state of matter called a quark-gluon plasma (QGP), a soup of fundamental particles that existed microseconds after the big bang. As this plasma cools, it transforms into hadronic matter, a phase composed of particles such as protons and neutrons, as well as other baryons and mesons.
The study focuses on what happens to heavy-flavour hadrons (particles containing charmed or background quarks, such as D and B mesons) during this transition and the hadronic phase expansion that follows it.
Heavy particles as probes
Heavy quarks are like tiny sensors. Being so massive, they are produced just after the initial nuclear collision and move more slowly, thus interacting differently with the surrounding matter. Knowing how they scatter and spread is key to learning about the properties of the medium through which they travel.
Researchers have reviewed a wide range of theoretical models and experimental data to understand how heavy hadrons, such as D and B mesons, interact with light particles in the hadronic phase. They have also examined how these interactions affect observable quantities such as particle flux and momentum loss.
