Suppression of Λ(1520) resonance production in central Pb-Pb collisions at √sNN=2.76 TeV

Abstract

The production yield of the Λ (1520) baryon resonance is measured at midrapidity in Pb-Pb collisions at √sNN = 2.76 TeV with the ALICE detector at the Large Hadron Collider (LHC). The measurement is performed in the Λ (1520) → pK − (and charge conjugate) hadronic decay channel as a function of the transverse momentum (pT) and collision centrality. The ratio of the pT -integrated production of Λ (1520) baryons relative to Λ baryons in central collisions is suppressed by about a factor of 2 with respect to peripheral collisions. This is the first observation of the suppression of a baryonic resonance at the LHC and the first 3 σ evidence of Λ (1520) suppression within a single collision system. The measured Λ (1520) / Λ ratio in central collisions is smaller than the value predicted by the statistical hadronization model calculations. The shape of the measured p T distribution and the centrality dependence of the suppression are reproduced by the EPOS3 Monte Carlo event generator. The measurement adds further support to the formation of a dense hadronic phase in the final stages of the evolution of the fireball created in heavy-ion collisions, lasting long enough to cause a significant reduction in the observable yield of short-lived resonances.