663 research outputs found
Anisotropic flow fluctuations in hydro-inspired freeze-out model for relativistic heavy ion collisions
The LHC data on event-by-event harmonic flow coefficients measured in PbPb
collisions at center-of-mass energy 2.76 TeV per nucleon pair are analyzed and
interpreted within the HYDJET++ model. To compare the model results with the
experimental data the unfolding procedure is employed. The essentially
dynamical origin of the flow fluctuations in hydro-inspired freeze-out approach
has been established. It is shown that the simple modification of the model via
introducing the distribution over spatial anisotropy parameters permits
HYDJET++ to reproduce both elliptic and triangular flow fluctuations and
related to it eccentricity fluctuations of the initial state at the LHC energy.Comment: 12 pages including 9 figures as EPS-files; prepared using LaTeX
package for publication in the European Physical Journal
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
Gamma-radiation as a Signature of Ultra Peripheral Ion Collisions at LHC energies
We study the peripheral ion collisions at LHC energies in which a nucleus is
excited to the discrete state and then emits -rays. Large nuclear
Lorenz factor allows to observe the high energy photons up to a few ten GeV and
in the region of angles of a few hundred micro-radians around the beam
direction. These photons can be used for tagging the events with particle
production in the central rapidity region in the ultra-peripheral collisions.
For that it is necessary to have an electromagnetic detector in front of the
zero degree calorimeter in the LHC experiments.Comment: 14 pages, 6 Postscript figure
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
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