Λ and $K^{0}_{S}$ production in Pb-Pb and pp collisions with ALICE at the LHC

In this work, the transverse momentum spectra of Λ and K^{0}_{S} measured with the ALICE experiment at the LHC are discussed. Measurements are presented for colliding systems of protons, at centre of mass energies 2.76 TeV and 7 TeV, and for lead ions at a centre of mass energy of 2.76 TeV per nucleon. The spectra are discussed within a theoretical framework of a thermally equilibrated, hydrodynamically evolving system, which serves to explain the shape of the spectra for p_{T} < 2 GeV/c. For p_{T} > 6 GeV/c jet quenching is evident, but no evidence of particle species dependance in jet quenching is observed. The Λ/K^{0}_{S} ratio shows an enhancement for 2 < p_{T} < 6 GeV/c, peaking at 1.5 for the 5% most central Pb–Pb collisions compared to 0.6 for pp. This is discussed in terms of a coalescence model. It cannot be explained purely by enhanced baryon production, but must also involve a redistribution of particles within p_{T}. This supports the hydrodynamical picture of hadron production. A brief comparison to the results presently available in p–Pb collisions at the LHC is also given.