Rescattering of Vector Meson Daughters in High Energy Heavy Ion Collisions

We consider the role of hadronic rescattering of daughter kaons on the observed mass spectra from $\phi$ meson decays in ultra-relativistic heavy ion collisions. A hadronic cascade code (RQMD v2.4) shows that $\sim$26% of all $\phi$'s decaying to $K^+K^-$ in central Pb+Pb collisions at SPS energies ($E_{beam} = 158 GeV/A$) have a rescattered or absorbed daughter. This significantly affects the reconstructed invariant mass of the pair and shifts $\phi$ mesons out of the mass peak. Kaon rescattering depletes the low velocity region, hardening and broadening the observed phi $m_t$ and rapidity distributions respectively, relative to the dilepton channel. This effect produces an apparent change in the experimentally determined branching ratio not necessarily related to chiral symmetry restoration. Comparisons to recent experimental measures at CERN energies reveal a possible mechanism to account for the shape of the observed spectra, though not their absolute relative magnitude.Comment: submitted to Eur Jour Phys

Microscopic theory of pion production and sidewards flow in heavy ion collisions

Nuclear collisions from 0.3 to 2 GeV/nucleon are studied in a microscopic theory based on Vlasov's self-consistent mean field and Uehling-Uhlenbeck's two-body collision term which respects the Pauli principle. The theory explains simultaneously the observed collective flow and the pion multiplicity and gives their dependence on the nuclear equation of state

Rapidity dependence of entropy production in proton- and nucleus-induced reactions on heavy nuclei

The entropy of hot nuclear systems is deduced from the mass distribution of fragments emitted from high energy proton- and nucleus-induced reactions via a quantum statistical model. It is found that the entropy per baryon, S/A, of intermediate rapidity ("participant") fragments is higher than the entropy of target rapidity ("spectator") fragments. The spectator fragments exhibit S/A values of ≅ 1.8 independent of the projectile energy from 30 MeV/nucleon up to 350 GeV. This value of the entropy coincides with the entropy at which nuclear matter becomes unbound

The Future of Quark Matter at RHIC

Projected annual results for heavy particle and high-p_{T} correlation studies at future RHICII luminosities.Comment: 8 pages, 3 figures. Proceedings for Quark Matter 2006, Shanghai, Chin

Measurement of complex fragments and clues to the entropy production from 42-137-MeV/nucleon Ar + Au

Intermediate-rapidity fragments with A=1-14 emitted from 42-137-MeV/nucleon Ar + Au have been measured. Evidence is presented that these fragments arise from a common moving source. Entropy values are extracted from the mass distributions by use of quantum statistical and Hauser-Feshbach theories. The extracted entropy values of S/A≈2-2.4 are much smaller than the values expected from measured deuteron-to-proton ratios, but are still considerably higher than theoretically predicted values

Light particle spectra from 35 MeV/nucleon 12C-induced reactions on 197Au

Energy spectra for p, d, t, 3He, 4He, and 6He from the reaction 12C+197Au at 35 MeV/nucleon are presented. A common intermediate rapidity source is identified using a moving source fit to the spectra that yields cross sections which are compared to analogous data at other bombarding energies and to several different models. The excitation function of the composite to proton ratios is compared with quantum statistical, hydrodynamic, and thermal models

The Hot QCD White Paper: Exploring the Phases of QCD at RHIC and the LHC

The past decade has seen huge advances in experimental measurements made in heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) and more recently at the Large Hadron Collider (LHC). These new data, in combination with theoretical advances from calculations made in a variety of frameworks, have led to a broad and deep knowledge of the properties of thermal QCD matter. Increasingly quantitative descriptions of the quark-gluon plasma (QGP) created in these collisions have established that the QGP is a strongly coupled liquid with the lowest value of specific viscosity ever measured. However, much remains to be learned about the precise nature of the initial state from which this liquid forms, how its properties vary across its phase diagram and how, at a microscopic level, the collective properties of this liquid emerge from the interactions among the individual quarks and gluons that must be visible if the liquid is probed with sufficiently high resolution. This white paper, prepared by the Hot QCD Writing Group as part of the U.S. Long Range Plan for Nuclear Physics, reviews the recent progress in the field of hot QCD and outlines the scientific opportunities in the next decade for resolving the outstanding issues in the field.Comment: 110 pages, 33 figures, 429 references. Prepared as part of the U.S. Long-Range Plan for Nuclear Physic