Speaker
Jens Wiechula
(Physikalisches Institut, Universität Tübingen)
Description
Heavy quarkonium states, such as the $J/\psi$, are expected to provide essential information on the properties of high-energy heavy-ion collisions where the formation of a Quark-Gluon Plasma is expected. The impact on the $J/\psi$ production of such a hot and dense medium formed in the early times of the collision has been extensively studied at SPS and RHIC energies. It is expected that due to colour screening mechanisms $J/\psi$ production is suppressed in a plasma of quarks and gluons. At LHC energies, however, charm is produced abundantly in central Pb--Pb collisions allowing for scenarios where originally uncorrelated charm and anti-charm quarks (re)combine at the phase boundary. Measuring the $J/\psi$ production at LHC will help to disentangle between the different mechanisms.
ALICE is the dedicated heavy-ion experiment at the LHC. Due to the unique particle identification capabilities of the central barrel detectors ($|\eta|<0.9$), $J/\psi$ can be measured in the di electron channel in the very demanding environment of central Pb--Pb collisions at LHC. In addition $J/\psi$ is measured at forward rapidity ($2.5 < y < 4$) with a dedicated muon spectrometer. ALICE is the only LHC experiment with a $J/\psi$ acceptance that reaches down to $p_t = 0$ at both mid- and forward-rapidity. First results on the nuclear modification factor of the inclusive $J/\psi$ production at mid-rapidity in Pb--Pb collisions at $\sqrt{s_{NN}}=2.76$\,TeV will be presented. The mid-rapidity measurement is complemented with the results obtained at forward-rapidity.
Primary author
Jens Wiechula
(Physikalisches Institut, Universität Tübingen)
