  A simple approach based on the separation of wounded nucleons in an A-A
collision in two categories, those suffering single collisions - corona and the
rest - core, estimated within a Glauber Monte-Carlo approach, explains the
centrality dependence of the light flavor hadrons production in Pb-Pb
collisions at $\sqrt{s_{NN}}$=2.76 TeV. The core contribution does not include
any dependence of any process on the fireball shape as a function of the impact
parameter. Therefore, the ratios of the $p_T$ distributions to the one
corresponding to the minimum bias pp collisions at the same energy, each of
them normalised to the corresponding charged particle density, the $\langle
p_T\rangle$ and transverse energy per unit of rapidity are reproduced less
accurate by such an approach. The results show that the corona contribution
plays an important role also at LHC energies and it has to be considered in
order to evidence the centrality dependence of different observables related to
the core properties and dynamics.
