596 research outputs found
New method for measuring longitudinal fuctuations and directed flow in ultrarelativistic heavy ion reactions
It has been shown in recent ALICE@LHC measurements that the odd flow
harmonics, in particular a directed flow, v1, occurred to be weak and dominated
by random fluctuations. In this work we propose a new method, which makes the
measurements more sensitive to the flow patterns showing global collective
symmetries. We demonstrate how the longitudinal center of mass rapidity
fluctuations can be identified, and then the collective flow analysis can be
performed in the event-by-event center of mass frame. Such a method can be very
effective in separating the flow patterns originating from random fluctuations,
and the flow patterns originating from the global symmetry of the initial
state.Comment: 8 pages, 2 figure
Influence of resonance decays on triangular flow in heavy-ion collisions
Anisotropic flow in relativistic collisions of heavy-ions yields important information about the state of the hot and dense matter created in the collision. Study of triangular flow in Pb+Pb collisions at LHC was performed using HYDJET++ Monte Carlo generator. HYDJET++ combines both hydrodynamics-driven soft part together with hard jet-part, giving a realistic prediction for vast number of hadron species. The model also enables study of influence of final-state interactions on flow of created hadrons. Triangular flow patterns of pions, kaons and protons were studied. We found that resonance decays influence significantly the shape of the distributions
HYDRO + JETS (HYDJET++) event generator for Pb+Pb collisions at LHC
The Monte Carlo event generator HYDJET++ is one of the few generators,
designed for the calculations of heavy-ion collisions at ultrarelativistic
energies, which combine treatment of soft hydro-like processes with the
description of jets traversing the hot and dense partonic medium. The model is
employed to study the azimuthal anisotropy phenomena, dihadron angular
correlations and event-by-event (EbyE) fluctuations of the anisotropic flow in
Pb+Pb collisions at TeV. The interplay of soft and hard
processes describes the violation of the mass hierarchy of meson and baryon
elliptic and triangular flows at p_T > 2 GeV/c, the fall-off of the flow
harmonics at intermediate transverse momenta, and the worsening of the
number-of-constituent-quark (NCQ) scaling of elliptic/triangular flow at LHC
compared to RHIC energies. The cross-talk of v_2 and v_3 leads to emergence of
higher order harmonics in the model and to appearance of the ridge structure in
dihadron angular correlations in a broad pseudorapidity range. HYDJET++
possesses also the dynamical EbyE fluctuations of the anisotropic flow. The
model results agree well with the experimental data.Comment: 8 pages, 6 figures, contribution to Proceedings of the Winter
Workshop on Nuclear Dynamics 201
Higher harmonics of azimuthal anisotropy in relativistic heavy ion collisions in HYDJET++ model
The LHC data on azimuthal anisotropy harmonics from PbPb collisions at
center-of-mass energy 2.76 TeV per nucleon pair are analyzed and interpreted in
the framework of the HYDJET++ model. The cross-talk of elliptic and
triangular flow in the model generates both even and odd harmonics of
higher order. Comparison with the experimental data shows that this mechanism
is able to reproduce the and centrality dependencies of
quadrangular flow , and also the basic trends for pentagonal and
hexagonal flows.Comment: 12 pages including 13 figures as EPS-files; prepared using LaTeX
package for publication in the European Physical Journal
Will jets reduce the elliptic flow at LHC, while decays of resonances restore the constituent quark scaling?
Formation and evolution of the elliptic flow pattern in Pb+Pb collisions at
sqrt{s}=5.5 ATeV and in Au+Au collisions at sqrt{s}=200 AGeV are analyzed for
different hadron species within the framework of HYDJET++ Monte-Carlo model.
The model contains both hydrodynamic state and jets, thus allowing for a study
of the interplay between the soft and hard processes. It is found that jets are
terminating the rise of the elliptic flow with increasing transverse momentum.
Since jets are more influential at LHC compared to RHIC, the elliptic flow at
LHC should be weaker than that at RHIC. The influence of resonance decays on
particle elliptic flow is investigated also. These final state interactions
enhance the low-p_T part of the v_2 of pions and light baryons, and work
towards the fulfilment of idealized constituent quark scaling.Comment: 8 pages, 9 figures, 3 table
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