Choose timezone
Your profile timezone:
CERN Heavy Ion Forum
1. Measurement of jet properties ... 2. Flow at RHIC within the Blast Wave framework 3. Jet sha
by
→
Europe/Zurich
160/1-009 (CERN)
Description
1. Measurement of jet properties and their modification in heavy-ion collisions at RHIC
by Jan Rak / Max-Planck-Institut fuer Kernphysik (MPI)
Heavy ion physics at Relativistic Heavy Ion Collider BNL finally entered a regime where pQCD phenomena can be fully explored. The anomalous suppression of high-p_T hadrons, now observed by all RHIC experiments, indicates that a substantial modification of jet properties is induced by the nuclear medium. Analysis of the two high-p_T particle correlation function allows the statistical disentanglement of jet fragment pairs apart from other sources of correlation, which lets us then examine the jet fragmentation process directly in heavy-ion collisions. The recent results from the two particle correlation analysis of p+p, d+Au and Au+Au data at sqrt{s_NN}=200 GeV will be discussed.
2. Flow at RHIC within the Blast Wave framework
by Fabrice Retiere, Université de Nantes
Au-Au collisions at RHIC produce a medium whose density appears to be large enough to absorb a significant amount of energy from fast partons and initiate a large collective expansion. Flow builds up over the whole evolution of the system possibly going through two distinct stages, one partonic and one hadronic. A wide variety of observables are sensitive to flow but they probe the final state of the system and its evolution needs to be inferred from models. Before describing the system evolution it is mandatory to tie up these observables together within models or parameterizations. We show that while most models fail, the Blast Wave parameterization is able to describe simultaneously spectra, v2, and pion source size (HBT). We then investigate flow features by studying its dependence on centrality, beam energy, and particle species. We find that within the Blast Wave framework, Xis flow less than pions, Kaons and protons, suggesting that Xis pick up flow only from the partonic stage because their hadronic cross-section is presumably small.
3. Jet shapes in non-static media: mapping the flow velocity
by Carlos Salgado, CERN
The suppression of particles with high-pt in high energy heavy ionscollisions have been proposed as a unique tool to measure the density ofthe produced medium. This suppression has been observed at RHIC, givingstrong support to the production of a very dense medium. Actually, thesensitivity of this probe to the density of the medium is limited by the'corona effect': due to the strong suppression, most of the particles areproduced close to the surface. Going beyond the leading particlemeasurements would improve the situation as, for radiative energy losses,the jet broadening is directly related to the energy loss of the leadingparticle. Moreover, in the case that a dynamical asymmetry is present inthe medium - for example a flow field - the jet shapes are distorted. Wewill present the first results of a jet measurement which is sensitive notonly to the density of the medium but also to its dynamics. Comparison with recent RHIC data and expectations for the LHC will be also presented.
by Jan Rak / Max-Planck-Institut fuer Kernphysik (MPI)
Heavy ion physics at Relativistic Heavy Ion Collider BNL finally entered a regime where pQCD phenomena can be fully explored. The anomalous suppression of high-p_T hadrons, now observed by all RHIC experiments, indicates that a substantial modification of jet properties is induced by the nuclear medium. Analysis of the two high-p_T particle correlation function allows the statistical disentanglement of jet fragment pairs apart from other sources of correlation, which lets us then examine the jet fragmentation process directly in heavy-ion collisions. The recent results from the two particle correlation analysis of p+p, d+Au and Au+Au data at sqrt{s_NN}=200 GeV will be discussed.
2. Flow at RHIC within the Blast Wave framework
by Fabrice Retiere, Université de Nantes
Au-Au collisions at RHIC produce a medium whose density appears to be large enough to absorb a significant amount of energy from fast partons and initiate a large collective expansion. Flow builds up over the whole evolution of the system possibly going through two distinct stages, one partonic and one hadronic. A wide variety of observables are sensitive to flow but they probe the final state of the system and its evolution needs to be inferred from models. Before describing the system evolution it is mandatory to tie up these observables together within models or parameterizations. We show that while most models fail, the Blast Wave parameterization is able to describe simultaneously spectra, v2, and pion source size (HBT). We then investigate flow features by studying its dependence on centrality, beam energy, and particle species. We find that within the Blast Wave framework, Xis flow less than pions, Kaons and protons, suggesting that Xis pick up flow only from the partonic stage because their hadronic cross-section is presumably small.
3. Jet shapes in non-static media: mapping the flow velocity
by Carlos Salgado, CERN
The suppression of particles with high-pt in high energy heavy ionscollisions have been proposed as a unique tool to measure the density ofthe produced medium. This suppression has been observed at RHIC, givingstrong support to the production of a very dense medium. Actually, thesensitivity of this probe to the density of the medium is limited by the'corona effect': due to the strong suppression, most of the particles areproduced close to the surface. Going beyond the leading particlemeasurements would improve the situation as, for radiative energy losses,the jet broadening is directly related to the energy loss of the leadingparticle. Moreover, in the case that a dynamical asymmetry is present inthe medium - for example a flow field - the jet shapes are distorted. Wewill present the first results of a jet measurement which is sensitive notonly to the density of the medium but also to its dynamics. Comparison with recent RHIC data and expectations for the LHC will be also presented.