Fluctuations of the Initial Conditions and the Continuous Emission in the Hydrodynamical Description of Two-Pion Interferometry

Abstract

Within the hydrodynamical approach, we study the Bose-Einstein correlation of identical pions by taking into account both event-by-event fluctuating initial conditions and continuous pion emission during the whole development of the hot and dense matter formed in high-energy collisions. Important deviations occur, compared to the usual hydrocalculations with smooth initial conditions and a sudden freeze-out on a well defined hypersurface. Comparison with data at the BNL Relativistic Heavy Ion Collider (RHIC) shows that, despite the rather rough approximation we used here, this description can account for the m(T) dependence of R(L) and R(s), and produces a significant improvement for R(o) with respect to the usual version.

Event-by-EventHydrodynamics+JetEnergy Loss: A Solution to theRAA⊗vNoronha-Hostler1, Betz2, Noronha3 et al. 2016Phys. Rev. Lett.11861573View full textAdd to dashboardCite

“…Our understanding of the bulk (soft) properties of the evolving medium has progressed immensely since the first event-by-event hydrodynamic simulations were carried out more than a decade ago [50][51][52][53]. It is now understood [54] that the initial spatial anisotropies present in the early stages of nucleus-nucleus collisions are converted to final stage momentum anisotropies (i.e., anisotropic flow) in a way that is consistent with viscous relativistic hydrodynamic simulations performed on an event-by-event basis (see, e.g., the review [47]).…”

The role of local and global strangeness neutrality at the inhomogeneous freeze-out in relativistic heavy ion collisions

“…Other signals, such as two-particle correlations [8,40], could also be analyzed in this regard. Future studies should shed more light on whether these inhomogeneities can indeed be interpreted as fingerprints of a first-order phase transition.…”

“…Rather, they are dominated by the stationary points of the distributions defined in eqs. (7,8) above. Hence, the average emission temperature T i and baryon-chemical potential µ B i in general depend on the particle species i, unless δT = δµ B = 0.…”

“…On the other hand, if the low-temperature and high-temperature regimes are smoothly connected, pressure gradients tend to wash out density inhomogeneities. Similarly, in the absence of phase-transition induced non-equilibrium effects, the predicted initial-state density inhomogeneities [7,8] should be strongly damped.…”

Fitted HBT radii versus space-time variances in flow-dominated models

“…They include a more realistic modeling of the final freeze-out stage [28], exploration of fluctuations in the initial state and ambiguities in the hydrodynamic decoupling criterion [29], viscous effects due to incomplete thermalization (i.e. inapplicability of ideal fluid dynamics) [30], different (more Landau-type) initial conditions leading to strong longitudinal hydrodynamic acceleration [31], and the use of more realistic or different equations of state (EoS) for the expanding matter [32].…”