Dynamical vs geometric anisotropy in relativistic heavy-ion collisions: which one prevails?

We study the influence of geometric and dynamical anisotropies on the development of flow harmonics and, simultaneously, on the second- and third-order oscillations of femtoscopy radii. The analysis is done within the Monte Carlo event generator HYDJET++, which was extended to dynamical triangular deformations. It is shown that the merely geometric anisotropy provides the results which anticorrelate with the experimental observations of either $v_2$ (or $v_3$) or second-order (or third-order) oscillations of the femtoscopy radii. Decays of resonances significantly increase the emitting areas but do not change the phases of the radii oscillations. In contrast to the spatial deformations, the dynamical anisotropy alone provides the correct qualitative description of the flow and the femtoscopy observables simultaneously. However, one needs both types of the anisotropy to match quantitatively the experimental data.Comment: minor corrections, published versio

Rapidity-dependence of jet shape broadening and quenching

The jet shape modification due to partonic energy loss in the dense QCD matter is investigated by the help of the special transverse energy-energy correlator in the vicinity of maximum energy deposition of every event. In the accepted scenario with scattering of jet hard partons off comoving medium constituents this correlator is independent of the pseudorapidity position of a jet axis and becomes considerably broader (symmetrically over the pseudorapidity and the azimuthal angle) in comparison with $pp$-collisions. At scattering off "slow" medium constituents the broadening of correlation functions is dependent on the pseudorapidity position of a jet axis and increases noticeably in comparison with the previous scenario for jets with large enough pseudorapidities. These two considered scenarios result also in the different dependence of jet quenching on the pseudorapidity.Comment: 9 pages, 7 figures, 1 table, RevTex4, typos corrected, accepted for publication in Phys. Rev.

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 $v_2$ and triangular $v_3$ 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 $p_{\rm T}$ and centrality dependencies of quadrangular flow $v_4$, and also the basic trends for pentagonal $v_5$ and hexagonal $v_6$ 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

Modeling the jet quenching, thermal resonance production and hydrodynamical flow in relativistic heavy ion collisions

The event topology in relativistic heavy ion collisions is determined by various multi-particle production mechanisms. The simultaneous model treatment of different collective nuclear effects at high energies (such as a hard multi-parton fragmentation in hot QCD-matter, thermal resonance production, hydrodynamical flows, etc.) is actual but rather complicated task. We discuss the simulation of the above effects by means of Monte-Carlo model HYDJET++.Comment: Talk given at Workshop "Hot Quarks 2010" (La Londe Les Maures, France, June 21-26, 2010); 4 pages including 2 figures as EPS-files; prepared using LaTeX package for publication in Journal of Physics: Conference Serie