Jet absorption and corona effect at RHIC. Extracting collision geometry from experimental data
V. S. Pantuev
University at Stony Brook, Stony Brook, NY 11794-3800, USA
Institute for Nuclear Research RAS, Moscow, Russia
PACS: 25.75.Nq, 52.27.Gr
Abstract
We demonstrate a possible existence of a finite formation time of
strongly interacting plasma in nuclear collisions at RHIC from recent
experimental data. To show this, we use a simple model based on Monte Carlo
simulation of nucleus-nucleus collisions with realistic nuclear density
distribution.
The most striking feature of the experimental data - an absence of
absorption of high transverse momentum pions in the reaction plane direction
for mid-peripheral collisions - points to the presence of a surface zone
with no absorption and strong suppression in the inner core. A natural
interpretation of such a zone could be the plasma formation time
fm/c. The existence of a formation time could dramatically
change our understanding of many experimentally observed features. With this
assumption we describe the angular anisotropy of high transverse momentum
pions with respect to the reaction plane and the centrality dependence of
nuclear modification factor in Au+Au and Cu+Cu collisions.