2,762 research outputs found
From kinetic theory to dissipative fluid dynamics
We present the results of deriving the Israel-Stewart equations of
relativistic dissipative fluid dynamics from kinetic theory via Grad's
14-moment expansion. Working consistently to second order in the Knudsen
number, these equations contain several new terms which are absent in previous
treatments.Comment: 7 pages, proceedings of the Erice School on Nuclear Physics "Heavy
Ion collisions from the Coulomb Barrier up to the Quark Gluon Plasma", Erice,
Sicily, Sep. 16 - 24, 200
Electron capture to continuum in collisions of bare projectiles with Ne targets
Abstract. We have investigated the cusp resulting from electron capture to the continuum of 1.25-5 MeV m u- ' fully stripped hydrogen and oxygen as a function of the collision energy and the detector angular resolution B o. It is revealed that the characteristic cusp shape parameters depend strongly on the experimental resolution. Our experimental data are "pared with the second-order Born theory and the impulse approximation. Both theories mnhrm the 8, dependence of the shape parameters and gjve a reasonable descrip-lion of the cusp asymmetry. However, theory tends to overestimate the absolute cross sections, in particular in the case of oxygen. 1
Mach Cones and Hydrodynamic Flow: Probing Big Bang Matter in the Laboratory
A critical discussion of the present signals for the phase transition to
quark-gluon plasma (QGP) is given. Since hadronic rescattering models predict
much larger flow than observed from 1 to 50 A GeV laboratory bombarding
energies, this observation is interpreted as potential evidence for a
first-order phase transition at high baryon density. 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 < 30 %
of the observed elliptic flow v_2 for GeV/c. This is interpreted as
an evidence for the production of superdense matter at RHIC. The connection of
v_2 to jet suppression is examined. A study of Mach shocks generated by fast
partonic jets propagating through the QGP is given. The main goal is to take
into account different types of collective motion during the formation and
evolution of this matter. A significant deformation of Mach shocks in central
Au+Au collisions at RHIC and LHC energies as compared to the case of jet
propagation in a static medium is predicted. A new hydrodynamical study of jet
energy loss is presented.Comment: 18 pages, 12 figures, presented at the IWCF 2006, Nov. 21-24,
Hangzhou, Chin
Universal Flow-Driven Conical Emission in Ultrarelativistic Heavy-Ion Collisions
The double-peak structure observed in soft-hard hadron correlations is
commonly interpreted as a signature for a Mach cone generated by a supersonic
jet interacting with the hot and dense medium created in ultrarelativistic
heavy-ion collisions. We show that it can also arise due to averaging over many
jet events in a transversally expanding background. We find that the
jet-induced away-side yield does not depend on the details of the
energy-momentum deposition in the plasma, the jet velocity, or the system size.
Our claim can be experimentally tested by comparing soft-hard correlations
induced by heavy-flavor jets with those generated by light-flavor jets.Comment: 4 pages, 3 figure
Spatial heterodyne interferometry of VY Canis Major's, alpha Orionis, alpha Scorpii, and R leonis at 11 microns
Using the technique of heterodyne interferometry, measurements were made of the spatial distribution of 11 micron radiation from four late type stars. The circumstellar shells surrounding VY Canis Majoris, alpha Orionis, and alpha Scorpii were resolved, whereas that of R Leonis was only partially resolved at a fringe spacing of 0.4 sec
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Real Time Detection and Tracking of Spatial Event Clusters
We demonstrate a system of tools for real-time detection of significant clusters of spatial events and observing their evolution. The tools include an incremental stream clustering algorithm, interactive techniques for controlling its operation, a dynamic map display showing the current situation, and displays for investigating the cluster evolution (time line and space-time cube)
Taking Measure of Ohio's Opioid Crisis
Opioid addiction, abuse, and overdose deaths have become the most pressing public health issue facing Ohio. Ohio leads the country in drug overdose deaths per capita, a rate that continues to rise, overwhelming families, communities, and local governments across the state. In this policy brief, we aim to contribute to the understanding of this unfolding crisis and highlight insights that can inform policymaking
Superadiabatic transitions in quantum molecular dynamics
We study the dynamics of a molecule’s nuclear wave function near an avoided crossing of two electronic energy levels for one nuclear degree of freedom. We derive the general form of the Schrödinger equation in the nth superadiabatic representation for all n є N. Using these results, we obtain closed formulas for the time development of the component of the wave function in an initially unoccupied energy subspace when a wave packet travels through the transition region. In the optimal superadiabatic representation, which we define, this component builds up monotonically. Finally, we give an explicit formula for the transition wave function away from the avoided crossing, which is in excellent agreement with high-precision numerical calculations
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