3,099 research outputs found
Refractive Distortions of Two-Particle Correlations from Classical Trajectory Calculations
Calculations of two-particle correlations usually assume particles interact
only pair-wise after their final collisions with third bodies. By considering
classical trajectories, we show that interactions with the mean field can alter
the spatial dimensions of the outgoing phase-space-density profiles by tens of
percent, consistent with more complicated quantum complications.Comment: 10 pages, 5 figure
General Charge Balance Functions, A Tool for Studying the Chemical Evolution of the Quark-Gluon Plasma
In the canonical picture of the evolution of the quark-gluon plasma during a
high-energy heavy-ion collision, quarks are produced in two waves. The first is
during the first fm/c of the collision, when gluons thermalize into the QGP.
After a roughly isentropic expansion that roughly conserves the number of
quarks, a second wave ensues at hadronization, 5-10 fm/c into the collision.
Since each hadron contains at least two quarks, the majority of quark
production occurs at this later time. For each quark produced in a heavy-ion
collision, an anti-quark of the same flavor is created at the same point in
space-time. Charge balance functions identify, on a statistical basis, the
location of balancing charges for a given hadron, and given the picture above
one expects the distribution in relative rapidity of balancing charges to be
characterized by two scales. After first demonstrating how charge balance
functions can be created using any pair of hadronic states, it will be shown
how one can identify and study both processes of quark production. By
considering balance functions of several hadronic species, and by performing
illustrative calculations, this class of measurement appears to hold the
prospect of providing the field's most stringent insight into the chemical
evolution of the QGP.Comment: 11 pages, 1 figure (explanations and steps added to derivations,
typos fixed, minor error in calculation fixed and some signs fixed
Shapes and Sizes from Non-Identical-Particle Correlations
I review the prospects for measuring source characteristics from correlations
other than those involving identical pions. Correlations generated from Coulomb
and strong interactions are shown to provide remarkable resolving power for
determining three-dimensional information, in some cases accessing more detail
than can be represented by Gaussian fits
Identifying the Charge Carriers of the Quark-Gluon Plasma
Charge correlations in lattice gauge calculations suggest that up, down and
strange charges move independently in the QGP (quark-gluon plasma), and that
the density of such charges is similar to what is expected from simple thermal
arguments. Here, we show how specific elements of the charge-charge correlation
matrix in the QGP survive hadronization and become manifest in final-state
charge-charge correlation measurements.Comment: 4 pages, 4 figure
Viewing the Chemical Evolution of the Quark-Gluon Plasma with Charge Balance Functions
Correlations from charge conservation are affected by when charge/anticharge
pairs are created during the course of a relativistic heavy ion collision. For
charges created early, balancing charges are typically separated by the order
of one unit of spatial rapidity by the end of the collision, whereas those
charges produced later in the collision are far more correlated. By analyzing
correlations from STAR for different species, I show that one can distinguish
the two separate waves of charge creation expected in a high-energy collision,
one at early times when the QGP is formed and a second at hadronization.
Further, I extract the density of up, down and strange quarks at in the QGP and
find agreement at the 20% level with expectations for a chemically thermalized
plasma.Comment: Proceedings of "Critical Point and the Onset of Deconfinement, Napa,
CA, March 2013, 9 pages, 3 figure
Refractive Distortions of Two-Particle Correlations
Using optical model calculations it has recently been shown that refractive
phenomena from the collective mean field can significantly alter the sizes
inferred from two-pion correlations. We demonstrate that such effects can be
accounted for in classical calculations if mean field effects are included.Comment: Proceedings for International Symposium on Multiparticle Dyanamics,
Kromeriz, Czech Republic, Aug. 200
Extending the Reach of Hydrodynamics
Recent and ongoing improvements to hydrodynamic treatments at RHIC are
extending the physics reach of hydrodynamics, and improving the phenomenology.
Here, the links between technological improvements and the extension of physics
are emphasized.Comment: Proceedings for Zimanyi '75 Workshop, Budapest, 200
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