Mainz 2012 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 37: Schwerionenkollisionen und QCD Phasen
HK 37.1: Group Report
Wednesday, March 21, 2012, 16:30–17:00, P 5
Particle Production in p+p and A+A and the Maximum-Entropy Principle — •Klaus Reygers1, Hans-Jürgen Pirner2, and Boris Kopeliovich3 — 1Physikalisches Institut, Universität Heidelberg — 2Institut für Theoretische Physik, Universität Heidelberg — 3Departamento de Fisica, Universidad Tecnica Frederico Santa Maria
We deduce the maximum-entropy state of partons created in proton-proton and nucleus-nucleus collisions. This state is characterized by a distribution function n(x,p⊥→) depending on the light-cone fraction x and the transverse momentum p⊥→ of forward or backward particles, respectively. The mean transverse momentum ⟨ |p⊥→| ⟩ determines the single parameter of the maximum-entropy distribution which is constrained by the sum of all light-cone momentum fractions being unity. The total multiplicity is related to the transverse area of the colliding Lorentz-contracted hadrons. Assuming parton-hadron duality we can compare the model to data from RHIC and LHC. In heavy-ion collisions, the shape of the dN/dη distributions as functions of the number of participants has a universal shape common to RHIC and LHC which is of geometric origin.