Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userTubular initial conditions and ridge formation
271
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
The 2D azimuth & rapidity structure of the two-particle correlations in relativistic A+A collisions is altered significantly by the presence of sharp inhomogeneities in superdense matter formed in such processes. The causality constraints enforce one to associate the long-range longitudinal correlations observed in a narrow angular interval, the so-called (soft) ridge, with peculiarities of the initial conditions of collision process. This studys objective is to analyze whether multiform initial tubular structures, undergoing the subsequent hydrodynamic evolution and gradual decoupling, can form the soft ridges. Motivated by the flux-tube scenarios, the initial energy density distribution contains the different numbers of high density tube-like boost-invariant inclusions that form a bumpy structure in the transverse plane. The influence of various structures of such initial conditions in the most central A+A events on the collective evolution of matter, resulting spectra, angular particle correlations and v_n-coefficients is studied in the framework of the HydroKinetic Model (HKM).
rate research
Read More
The two component Monte-Carlo Glauber model predicts a knee-like structure in the centrality dependence of elliptic flow $v_2$ in Uranium+Uranium collisions at $sqrt{s_{NN}}=193$ GeV. It also produces a strong anti-correlation between $v_2$ and $dN_{ch}/dy$ in the case of top ZDC events. However, none of these features have been observed in data. We address these discrepancies by including the effect of nucleon shadowing to the two component Monte-Carlo Glauber model. Apart from addressing successfully the above issues, we find that the nucleon shadow suppresses the event by event fluctuation of various quantities, e.g. $varepsilon_2$ which is in accordance with expectation from the dynamical models of initial condition based on gluon saturation physics.
We show that a Bjorken expanding strongly coupled $mathcal{N}=4$ Supersymmetric Yang-Mills plasma can violate the dominant and also the weak energy condition in its approach to hydrodynamics (even though the chosen initial data satisfy these constraints). This suggests that nontrivial quantum effects may be needed to describe the onset of hydrodynamic behavior in heavy-ion collisions. Also, we investigate whether there is an upper bound for the initial entropy of the plasma. We find numerical evidence for such a bound in our simulations and show that close to it the system evolves with approximately zero entropy production at early times, even though it is far from equilibrium.
A simple approach is proposed allowing actual calculations of the preequilibrium dynamics in ultrarelativistic heavy-ion collisions to be performed for a far-from-equilibrium initial state. The method is based on the phenomenological macroscopic equations that describe the relaxation dynamics of the energy-momentum tensor and are motivated by Boltzmann kinetics in the relaxation-time approximation. It gives the possibility to match smoothly a nonthermal initial state to the hydrodynamics of the quark gluon plasma. The model contains two parameters, the duration of the prehydrodynamic stage and the initial value of the relaxation-time parameter, and allows one to assess the energy-momentum tensor at a supposed time of initialization of the hydrodynamics.
We present a Principal Component Analysis for a hydrodynamic simulation and compare with CMS experimental data. While the results are reasonable for anisotropic flow, for multiplicity fluctuations they are qualitatively different. We argue that this is due to too large transverse momentum ($p_T$) fluctuations and $N-p_T$ covariance in the simulation than seen experimentally. In turn this is related to too large initial size fluctuations.
We study effects of eccentricity fluctuations on the elliptic flow coefficient v_2 at mid-rapidity in both Au+Au and Cu+Cu collisions at sqrt{s_{NN}}=200 GeV by using a hybrid model that combines ideal hydrodynamics for space-time evolution of the quark gluon plasma phase and a hadronic transport model for the hadronic matter. We find that the effect of eccentricity fluctuation is modest in semicentral Au+Au collisions but significantly enhances v_2 in Cu+Cu collisions.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
