Comparing pp, pA to AA. Reaction centrality.

• Determination of the properties of the hot strongly interacting medium formed in A+A collisions requires comparing to:

• • No medium data : p+p collisions
  • Cold medium data: p+A collisions

• Particle production cross-sections in AA reactions scale according to the collision geometry (impact parameter). Reaction centrality is determined through: Glauber eikonal model + Global Detectors (ZDC, BBC) response

Notes: