Charmonium in Medium: From Correlators to Experiment

We set up a framework in which in-medium charmonium properties are constrained by thermal lattice QCD and subsequently implemented into a thermal rate equation enabling the comparison with experimental data in heavy-ion collisions. Specifically, we evaluate phenomenological consequences for charmonium production originating from two different scenarios in which either the free or the internal energy are identified with the in-medium 2-body potential between charm and anti-charm quarks. These two scenarios represent $J/\psi$ "melting temperatures" of approximately 1.25\,$T_c$ ("weak binding") and 2\,$T_c$ ("strong binding"), respectively. Within current uncertainties in dissociation rates and charm-quark momentum spectra, both scenarios can reproduce the centrality dependence of inclusive $J/\psi$ yields in nuclear collisions at SPS and RHIC reasonably well. However, the "strong-binding" scenario associated the the internal energy as the potential tends to better reproduce current data on transverse momentum spectra at both SPS and RHIC.Comment: 18 pages, 30 figure

Quarkonia and Heavy-Quark Relaxation Times in the Quark-Gluon Plasma

A thermodynamic T-matrix approach for elastic 2-body interactions is employed to calculate spectral functions of open and hidden heavy-quark systems in the Quark-Gluon Plasma. This enables the evaluation of quarkonium bound-state properties and heavy-quark diffusion on a common basis and thus to obtain mutual constraints. The two-body interaction kernel is approximated within a potential picture for spacelike momentum transfers. An effective field-theoretical model combining color-Coulomb and confining terms is implemented with relativistic corrections and for different color channels. Four pertinent model parameters, characterizing the coupling strengths and screening, are adjusted to reproduce the color-average heavy-quark free energy as computed in thermal lattice QCD. The approach is tested against vacuum spectroscopy in the open (D, B) and hidden (Psi and Upsilon) flavor sectors, as well as in the high-energy limit of elastic perturbative QCD scattering. Theoretical uncertainties in the static reduction scheme of the 4-dimensional Bethe-Salpeter equation are elucidated. The quarkonium spectral functions are used to calculate Euclidean correlators which are discussed in light of lattice QCD results, while heavy-quark relaxation rates and diffusion coefficients are extracted utilizing a Fokker-Planck equation.Comment: 33 pages, 28 figure

An apparent statistical relationship between polar heat budget and zonal circulation

Apparent statistical correlation between Arctic heat budget and zonal circulatio

Medium Modifications of Charm and Charmonium in High-Energy Heavy-Ion Collisions

The production of charmonia in heavy-ion collisions is investigated within a kinetic theory framework simultaneously accounting for dissociation and regeneration processes in both quark-gluon plasma (QGP) and hadron-gas phases of the reaction. In-medium modifications of open-charm states (c-quarks, D-mesons) and the survival of J/psi mesons in the QGP are included as inferred from lattice QCD. Pertinent consequences on equilibrium charmonium abundances are evaluated and found to be especially relevant to explain the measured centrality dependence of the psi'/psi ratio at SPS. Predictions for recent In-In experiments, as well as comparisons to current Au-Au data from RHIC, are provided.Comment: 4 Latex pages including 4 eps figures and IOP style files. Talk given at the 17th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, Quark Matter 2004, Oakland, CA USA, 11-17 Jan 2004. To appear in J. Phys.

Heavy-Quark Diffusion and Hadronization in Quark-Gluon Plasma

We calculate diffusion and hadronization of heavy quarks in high-energy heavy-ion collisions implementing the notion of a strongly coupled quark-gluon plasma in both micro- and macroscopic components. The diffusion process is simulated using relativistic Fokker-Planck dynamics for elastic scattering in a hydrodynamic background. The heavy-quark transport coefficients in the medium are obtained from non-perturbative $T$-matrix interactions which build up resonant correlations close to the transition temperature. The latter also form the basis for hadronization of heavy quarks into heavy-flavor mesons via recombination with light quarks from the medium. The pertinent resonance recombination satisfies energy conservation and provides an equilibrium mapping between quark and meson distributions. The recombination probability is derived from the resonant heavy-quark scattering rate. Consequently, recombination dominates at low transverse momentum ($p_T$) and yields to fragmentation at high $p_T$. Our approach thus emphasizes the role of resonance correlations in the diffusion and hadronization processes. We calculate the nuclear modification factor and elliptic flow of $D$- and $B$-mesons for Au-Au collisions at the Relativistic Heavy Ion Collider, and compare their decay-electron spectra to available data. We also find that a realistic description of the medium flow is essential for a quantitative interpretation of the data.Comment: 16 pages, 14 figure

Gut Microbiome Analysis in Morphine Exposure and Naltrexone-Induced Withdrawal

Introduction and Objectives: Relatively little is understood about the underlying physiological changes that occur in the withdrawal state of opiate users. Research on the effects of alcohol withdrawal on the Gut-brain axis (GBA) has revealed shifts in relative numbers of specific bacterial species that correlate with increased central nervous system (CNS) inflammation via neurological crosstalk. The purpose of this research was to determine if similar shifts in the relative abundance of bacterial populations occur in the opiate withdrawal state. Methods: Fourteen rats were randomized into four groups. Control and experimental rats were administered 75 mg morphine pellets or placebo (sugar) pellets subdermally. Within these two groups, the rats were given either naltrexone (simulates withdrawal) or nothing. Rats given naltrexone injections were sacrificed on day five and control rats on day 6. The rats were dissected, and stool from the cecum was extracted using the Qiagen DNA extraction mini kit. Finally, qPCR was run to examine changes in bacterial colonies in the control, opiate, and withdrawal groups. Results: The results showed a general shift in genus predominance from Firmicutes (control) to Bacteroides (withdrawal). This shift was only seen in rats in the withdrawal state and not in those only exposed to morphine or in the control conditions. Discussion: These bacterial shifts were similar to those seen in the numerous alcohol withdrawal studies that this research was modeled after. This may suggest similar underlying pathogenesis of gut dysbiosis from opiate withdrawal leading to CNS inflammation via vagal nerve signaling in the GBA

Secondary charging effects due to icy dust particle impacts on rocket payloads

We report measurements of dust currents obtained with a small probe and a larger probe during the flight of the ECOMA-4 rocket through the summer polar mesosphere. The payload included two small dust probes behind a larger dust probe located centrally at the front. For certain phases of the payload rotation, the current registered by one of the small dust probes was up to 2 times the current measured with the larger probe, even though the effective collection area of the larger probe was 4 times that of the small one. We analyze the phase dependence of the currents and their difference with a model based on the assumption that the small probe was hit by charged dust fragments produced in collisions of mesospheric dust with the payload body. Our results confirm earlier findings that secondary charge production in the collision of a noctilucent cloud/Polar Summer Mesospheric Echo (NLC/PMSE) dust particle with the payload body must be several orders of magnitude larger than might be expected from laboratory studies of collisions of pure ice particles with a variety of clean surfaces. An important consequence is that for some payload configurations, one should not assume that the current measured with a detector used to study mesospheric dust is simply proportional to the number density of ambient dust particles. The higher secondary charge production may be due to the NLC/PMSE particles containing multiple meteoric smoke particles

Oxygen dynamics in choanosomal sponge explants

Oxygen microprofiles were measured over the boundary layer and into the tissue of 10-day-old cultivated tissue fragments (explants of 2–4 cm3) from the choanosome of the cold-water sponge Geodia barretti with oxygen-sensitive Clark-type microelectrodes. At this time of cultivation, the surface tissue and the aquiferous system of the explants is regenerating, which makes oxygen and nutrient supply by pumping activity impossible. Oxygen profiles showed a parabolic shape, indicating oxygen flux over a diffusive boundary layer and into the tissue. Oxygen was always depleted only 1 mm below the sponge surface, leaving the major part of the explants anoxic. Diffusive oxygen flux into the explant was calculated from three oxygen profiles using Fick's first law of diffusion and revealed 9 μmol O2 cm−3 day−1, which is in the lower range of in situ oxygen consumption of whole sponges. The ability of G. barretti to handle continuous tissue anoxia enables choanosomal explants to survive the critical first weeks of cultivation without a functional aquiferous system, when oxygen is supplied to the sponge explant by molecular diffusion over its surface

PHENIX first measurement of the J/psi elliptic flow parameter v2 in Au+Au collisions at sqrt(sNN) = 200 GeV

Recent results indicate that the J/psi suppression pattern differs with rapidity showing a larger suppression at forward rapidity. J/psi suppression mechanisms based on energy density (such as color screening, interaction with co-movers, etc.) predict the opposite trend. On the other hand, it is expected that more c\bar{c} pairs should be available to form quarkonia at mid-rapidity via recombination. Some models provide a way to differentiate J/psi production from initially produced c\bar{c} pairs and final state recombination of uncorrelated pairs, via the rapidity and transverse momentum dependence of the elliptic flow (v2). During 2007 data taking at RHIC, a large sample of Au+Au collisions at sqrt(sNN)=200 GeV was collected. The statistics has been increased compared to previous 2004 data set, thus allowing a more precise measurement of the J/psi production at both mid and forward rapidity. Furthermore, the PHENIX experiment benefited from the addition of a new detector, which improves the reaction plane resolution and allows us to measure the J/psi v2. Comparing this measurement to the positive D-mesons v2 (through non-photonic electron decays) will help constraining the J/psi production mechanisms and getting a more precise picture of the proportion of J/psi coming from direct production or charm quark coalescence. Details on how the J/psi v2 is measured at both rapidities are presented. The J/psi v2 as a function of transverse momentum are compared to existing models.Comment: 4 pages, 3 figures, Quark Matter 2008 proceeding