Webpages tagged with «ALICE»

The QGP behaves like a low-viscosity liquid and exhibits a collective, multi-harmonic azimuthally anisotropic expansion pattern (flow), which can be described in terms of a Fourier series. The various Fourier components v_n originate from pressure gradients, due to the collision geometry in non-central collisions (typically the quadrupole component v₂, called elliptic flow) or to fluctuations in the initial nucleon density (typically triangular flow v₃ and higher order components). 

Late autumn 2018, the ALICE experiment collected a high-statistics data set with Pb-Pb collisions at a centre-of-mass energy of 5.02 TeV. High-quality reference data from p-p collisions at the same energy are also available.

Heavy nuclei at ultrarelativistic speeds are sources of intense electromagnetic fields which interact with the nuclear collision partner and lead to photoproduction of charm-anticharm quark pairs. The charm photoproduction cross section is sensitive to the gluonic nuclear structure, which depends on initial-state cold nuclear matter effects like gluon saturation.  

Ultra-relativistic heavy-ion collisions offer a unique opportunity to study the nuclear phase diagram at high temperatures and densities. The matter under such extreme conditions probably has existed in the early Universe within the first few fm/c after the Big Bang. Therefore, it is very tempting to investigate the properties of the Little Big Bang in the laboratory, and to search for a new state of matter, predicted by the fundamental theory of strong interactions - Quantum Chromodynamics (QCD), namely, a plasma of deconfined quarks and gluons or quark-gluon plasma (QGP).

The mission of the HENP project is the exploration of the behaviour of nuclear matter under extreme conditions and in particular the Quark-Gluon Plasma, which existed for about a microsecond after the Big Bang, and which can be recreated in ultra-relativistic heavy-ion collisions in the laboratory. The HENP project uses the Large Hadron Collider (LHC) at CERN and the dedicated heavy-ion experiment ALICE to produce and study the Quark-Gluon Plasma.