Séminaire spécialisé

jeudi 28 mars 2013 à 11:20


Heavy-flavours as probes of the Quark-Gluon Plasma: selection of measurements by the ALICE detector at the LHC and perspectives in view of the inner tracker upgrade

Chiara Bianchin

Utrecht University

The ALICE experiment at the LHC studies Pb-Pb and pp collisions with the aim of investigating the properties of the high-density state of strongly-interacting matter, expected to be produced in Pb-Pb collisions.

Heavy quarks are sensitive probes to test the medium properties, since they are formed at shorter time scale with respect to the deconfined state. They lose energy by interacting with the medium via radiative and collisional mechanisms. Low-momentum heavy quarks may eventually thermalize in the system and form hadrons via in-medium recombination.

Experimentally, energy loss can be studied using the nuclear modification factor (RAA), which is the suppression of the particle yields measured in Pb-Pb collisions with respect to the expectation from pp collisions scaled by the number of nucleon-nucleon collisions. The measurement of the RAA of heavy-flavoured particles allows us to address the mass and colour charge dependence of energy loss.

The degree of thermalization of heavy quarks can be assessed by measuring the final state azimuthal angle distribution of the heavy-flavoured particles with respect to the event plane, in particular the second harmonic coefficient of the Fourier expansion v2, known as elliptic flow.

This seminar will focus on the measurement of D meson RAA and v2. D mesons are detected in ALICE via their hadronic decays. The signal is extracted with an invariant mass analysis of displaced secondary vertices selected according to topological criteria and particle identification.

Finally the perspectives for the physics measurements that can be achieved with an upgraded Inner Tracking System, with improved spatial and momentum resolution and high rate capabilities, will be drawn.