Experimentations utilizing heavy ions at CERN’s Large Hadron Collider (LHC) have made significant advancements in understanding the primordial universe.
The CMS, ATLAS, and ALICE partnerships will present their new measurements of the matter that possibly existed during the first moments of the universe at the Quark Matter 2012 conference. These new results are primarily on the basis of the four-week LHC run with lead ions last year.
Immediately after the big bang, fundamental building blocks of matter, namely quarks and gluons were not detained within composite particles like neutrons and protons, as they are today, but moved freely in a form of matter dubbed as ‘quark–gluon plasma.’ Lead ion collisions in the LHC have recreated the conditions like those of the early universe. By investigating billions of these collisions, the tests were able to accurately measure the characteristics of matter under these extreme environments.
At the conference, the CMS, ATLAS, and ALICE collaborations will deliver more refined properties of the hottest and densest matter ever explored in a lab. The matter is 100,000 folds denser than a neutron star and hotter than the Sun’s interior.
ALICE will deliver new findings on all features of the evolution of strongly interacting, high-density matter in both time and space. Key analyses address ‘charmed particles’ that comprise a charm or an anticharm quark. Charm quarks, which are 100 folds heavier when compared to up and down quarks that create normal matter, are considerably slowed down when they traverse through quark–gluon plasma, providing an innovative tool to physicists to explore its properties. ALICE experiment has observed that the strong plasma flow has dragged the heavy charmed particles along with it. It has also noticed a thermalization phenomenon that involves the formation of ‘charmonium’ through the reunion of charm and anticharm quarks.
The LHC’s higher energy enables the physicists to explore similar tightly-bound forms of the heavier beauty quarks for the first time. The theory was that based on their binding energy, some of these states may get melted in the plasma generated, while others may withstand the extreme temperature. The CMS experiment has clearly noticed the signs of the anticipated sequential suppression of the ‘quarkonium.’
ATLAS will present new results on jet quenching, wherein particles’ highly energetic sprays disintegrate in the dense quark–gluon plasma, thus providing more insights into the properties and density of the resulting matter. ATLAS findings include a high-precision analysis of how the jets break up in matter, and the correlations between electroweak bosons and jets.
Source: http://cern.ch