Tuesday, March 27, 2012

1203.5704 (K. Werner et al.)

Jets, Bulk Matter, and their Interaction in Heavy Ion Collisions at Several TeV    [PDF]

K. Werner, Iu. Karpenko, M. Bleicher, T. Pierog, S. Porteboeuf-Houssais
We discuss a theoretical scheme which accounts for bulk matter, jets, and the interaction between the two. The aim is a complete description of particle production at all transverse momentum ($p_{t}$) scales. In this picture, the hard initial scatterings result in mainly longitudinal flux tubes, with transversely moving pieces carrying the $p_{t}$ of the partons from hard scatterings. These flux tubes constitute eventually both bulk matter (which thermalizes and flows) and jets. We introduce a criterion based on parton energy loss to decide whether a given string segment contributes to the bulk or leaves the matter to end up as a jet of hadrons. Essentially low $p_{t}$ segments from inside the volume will constitute the bulk, high $p_{t}$ segments (or segments very close to the surface) contribute to the jets. The latter ones appear after the usual flux tube breaking via q-qbar production (Schwinger mechanism). Interesting is the transition region: Intermediate $p_{t}$ segments produced inside the matter close to the surface but having enough energy to escape, are supposed to pick up q-qbar pairs from the thermal matter rather than creating them via the Schwinger mechanism. This represents a communication between jets and the flowing bulk matter (fluid-jet interaction). Also very important is the interaction between jet hadrons and the soft hadrons from the fluid freeze out. We employ the new picture to investigate PbPb collisions at 2.76 TeV. We discuss the centrality and $p_{t}$ dependence of particle production and long range dihadron correlations at small and large $p_{t}$.
View original: http://arxiv.org/abs/1203.5704

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