C.E. Aguiar

Collective Flow Signals the Quark-Gluon Plasma

A critical discussion of the present status of the CERN experiments on hadron collective flow is given. We emphasize the importance of the flow excitation function from 1 to 50 A·GeV: here the hydrodynamic model has predicted the collapse of the ]]> v_1

Smoothed particle hydrodynamics for relativistic heavy-ion collisions

flow and of the v2 flow at ∼10 A·GeV; at 40 A·GeV it has been recently observed by the NA49 Collaboration. Since hadronic rescattering models predict much larger flow than observed at this energy we interpret this observation as potential evidence for a first order phase transition at high baryon density ρB. A detailed discussion of the collective flow as a barometer for the equation of state (EoS) of hot dense matter at RHIC follows. Here, hadronic rescattering models can explain 2 GeV/c. This is interpreted as evidence for the production of superdense matter at RHIC with initial pressure far above hadronic pressure, p > 1 GeV/fm3. We suggest that the fluctuations in the flow, v1 and v2, should be measured in future since ideal hydrodynamics predicts that they are larger than 50% due to initial state fluctuations. Furthermore, the QGP coefficient of viscosity may be determined experimentally from the fluctuations observed.

Event-by-event fluctuations in hydrodynamical description of heavy-ion collisions

A smoothed particle hydrodynamics (SPH) method is developed for the study of relativistic heavy-ion collisions. In order to describe the flow of a high-energy but low baryon number density fluid, entropy is taken as the SPH base. The method is formulated in terms of a variational principle, and the SPH equations for an arbitrary curvilinear coordinate system are obtained. Several examples show that SPH is a promising tool for the study of hadronic flow in relativistic heavy-ion processes.

Listening to the coefficient of restitution and the gravitational acceleration of a bouncing ball

Effects caused by the event-by-event fluctuation of the initial conditions in hydrodynamical description of high-energy heavy-ion collisions are investigated. Non-negligible effects appear for several observable quantities, even for a fixed impact parameter

Liquid-drop model description of heavy ion fusion at sub-barrier energies

\vec b

A aerodinâmica da bola de futebol

. They are sensitive to the equation of state, being the dispersions of the observable quantities in general smaller when the QGP phase appears at the beginning of hydrodynamic evolution than when the fluid remains hadron gas during whole the evolution.

THERMAL FLUCTUATIONS IN HEAVY-ION FUSION REACTIONS (I). One-dimensional models

We show that a well known method for measuring the coefficient of restitution of a bouncing ball can also be used to obtain the gravitational acceleration.

Using the Sound Card as a Timer

Abstract The enhancement of the heavy ion fusion cross section at sub-barrier energies is studied in the liquid-drop model approach. The shape of the system is described by two spheres smoothly connected by a neck, and the kinetic and potential energies are calculated within this parametrization. Underbarrier fusion cross sections for symmetric projectile-target combinations are calculated in the WKB approximation and a comparison with the available data is made. The agreement is quite satisfactory, except for those systems in which the reaction is strongly affected by the details of the nuclear structure of the collision partners.

NeXSPheRIO results on elliptic-flow fluctuations at RHIC

We study the aerodynamic forces acting on a soccer ball. Analyzing the video of a famous shot by Pele, we show that a curious phenomenon, the drag crisis, greatly influenced the motion of the ball. The Magnus effect, caused by the rotation of the ball, was also important to the outcome of the kick. Using a computer code that simulates the flight of balls we discuss several aspects of Peles shot and of soccer physics, in particular bending kicks and Didis dry leaf.

Hydrodynamical instabilities in an expanding quark gluon plasma

Abstract We consider the effect of thermal fluctuations on the heavy-ion fusion probabilities calculated within different models of the nuclear potential and dissipation function. We show that the introduction of fluctuations has effects that depend considerably on the model utilized, and which may therefore help decide among the different theoretical descriptions now available.