5 research outputs found
Global Conservation Laws and Femtoscopy of Small Systems
It is increasingly important to understand, in detail, two-pion correlations
measured in p+p and d+A collisions. In particular, one wishes to understand the
femtoscopic correlations, in order to compare to similar measurements in heavy
ion collisions. However, in the low-multiplicity final states of these systems,
global conservation laws generate significant N-body correlations which project
onto the two-pion space in non-trivial ways and complicate the femtoscopic
analysis. We discuss a model-independent formalism to calculate and account for
these correlations in measurements.Comment: 7 pages; 10 figures; Invited talk at the Second Workshop on Particle
Correlations and Femtoscopy (WPCF06), Sept 9-11 2006, Sao Paulo, Brazi
Do p+p Collisions Flow at RHIC? Understanding One-Particle Distributions, Multiplicity Evolution, and Conservation Laws
Collective, explosive flow in central heavy ion collisions manifests itself
in the mass dependence of distributions and femtoscopic length scales,
measured in the soft sector ( GeV/c). Measured
distributions from proton-proton collisions differ significantly from those
from heavy ion collisions. This has been taken as evidence that p+p collisions
generate little collective flow, a conclusion in line with naive expectations.
We point out possible hazards of ignoring phase-space restrictions due to
conservation laws when comparing high- and low-multiplicity final states.
Already in two-particle correlation functions, we see clear signals of such
phase-space restrictions in low-multiplicity collisions at RHIC. We discuss how
these same effects, then, {\it must} appear in the single particle spectra. We
argue that the effects of energy and momentum conservation actually dominate
the observed systematics, and that collisions may be much more similar to
heavy ion collisions than generally thought.Comment: 4 pages, 3 figures - To appear in the conference proceedings for
Quark Matter 2009, March 30 - April 4, Knoxville, Tennesse
Status and promise of particle interferometry in heavy-ion collisions
After five years of running at RHIC, and on the eve of the LHC heavy-ion program, we highlight the status of femtoscopic measurements. We emphasize the role interferometry plays in addressing fundamental questions about the state of matter created in such collisions, and present an enumerated list of measurements, analyses and calculations that are needed to advance the field in the coming years
The ASY-EOS Experiment at GSI
The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of heavy ions at pre-relativistic energies has been proposed as an observable sensitive to the strength of the symmetry term of the nuclear equation of state at supra-saturation densities. In the ASY-EOS experiment at the GSI laboratory, flows of neutrons and light charged particles were measured for 197Au+197Au collisions at 400 MeV/nucleon. Flow results obtained for the Au+Au system, in comparison with predictions of the UrQMD transport model, confirm the moderately soft to linear density dependence of the symmetry energy deduced from the earlier FOPI-LAND data
Dense Nuclear Matter Equation of State from Heavy-Ion Collisions
The nuclear equation of state (EOS) is at the center of numerous theoretical
and experimental efforts in nuclear physics. With advances in microscopic
theories for nuclear interactions, the availability of experiments probing
nuclear matter under conditions not reached before, endeavors to develop
sophisticated and reliable transport simulations to interpret these
experiments, and the advent of multi-messenger astronomy, the next decade will
bring new opportunities for determining the nuclear matter EOS, elucidating its
dependence on density, temperature, and isospin asymmetry. Among controlled
terrestrial experiments, collisions of heavy nuclei at intermediate beam
energies (from a few tens of MeV/nucleon to about 25 GeV/nucleon in the
fixed-target frame) probe the widest ranges of baryon density and temperature,
enabling studies of nuclear matter from a few tenths to about 5 times the
nuclear saturation density and for temperatures from a few to well above a
hundred MeV, respectively. Collisions of neutron-rich isotopes further bring
the opportunity to probe effects due to the isospin asymmetry. However,
capitalizing on the enormous scientific effort aimed at uncovering the dense
nuclear matter EOS, both at RHIC and at FRIB as well as at other international
facilities, depends on the continued development of state-of-the-art hadronic
transport simulations. This white paper highlights the role that heavy-ion
collision experiments and hadronic transport simulations play in understanding
strong interactions in dense nuclear matter, with an emphasis on how these
efforts can be used together with microscopic approaches and neutron star
studies to uncover the nuclear EOS