Jet modification in three dimensional fluid dynamics at next-to-leading twist

The modification of the single inclusive spectrum of high transverse momentum ($p_T$) pions emanating from an ultra-relativistic heavy-ion collision is investigated. The deconfined sector is modelled using a full three dimensional (3-D) ideal fluid dynamics simulation. Energy loss of high $p_T$ partons and the ensuing modification of their fragmentation is calculated within perturbative QCD at next-to-leading twist, where the magnitude of the higher twist contribution is modulated by the entropy density extracted from the 3-D fluid dynamics simulation. The nuclear modification factor ($R_{AA}$) for pions with a $p_T \geq 8$ GeV as a function of centrality as well as with respect to the reaction plane is calculated. The magnitude of contributions to the differential $R_{AA}$ within small angular ranges, from various depths in the dense matter is extracted from the calculation and demonstrate the correlation of the length integrated density and the $R_{AA}$ from a given depth. The significance of the mixed and hadronic phase to the overall magnitude of energy loss are explored.Comment: 5 pages, 4 figures, Revte

Possible Resolutions of the D-Paradox

We propose possible ways of explaining the net charge event-by-event fluctuations in Au+Au collisions at the Relativistic Heavy Ion Collider within a quark recombination model. We discuss various methods of estimating the number of quarks at recombination and their implications for the predicted net charge fluctuations. We also discuss the possibility of diquark and quark-antiquark clustering above the deconfinement temperature.Comment: 5 pages, 2 figure

Resonance Production in RHIC Collisions

Results of resonance particle production measured at RHIC in $\sqrt{s_{\rm NN}} =$ 200 GeV Au+Au collisions are compared to measurements in p+p and d+Au collisions in order to verify the existence of an extended hardronically interacting medium. Yield and momentum distributions of resonances maybe modified during the fireball lifetime due to resonance decay and the subsequent rescattering of their decay daughters as well as the regeneration of resonances from their decay products. Modified momentum spectra in heavy ion collisions may change the nuclear modification factor R$_{\rm AA}$. The influence on the elliptic flow v$_{2}$ due to late regeneration of resonances is discussed.Comment: 6 pages, 6 figures, Proceedings of the 22st Winter Workshop on Nuclear Dynamics, San Diago, California, 12-18 March, 200

Effects of environment and genotype on dispersal differ across departure, transfer and settlement in a butterfly metapopulation

Active dispersal is driven by extrinsic and intrinsic factors at the three stages of departure, transfer and settlement. Most empirical studies capture only one stage of this complex process, and knowledge of how much can be generalized from one stage to another remains unknown. Here we use genetic assignment tests to reconstruct dispersal across 5 years and 232 habitat patches of a Glanville fritillary butterfly (Melitaea cinxia) metapopulation. We link individual dispersal events to weather, landscape structure, size and quality of habitat patches, and individual genotype to identify the factors that influence the three stages of dispersal and post-settlement survival. We found that nearly all tested factors strongly affected departure probabilities, but that the same factors explained very little variation in realized dispersal distances. Surprisingly, we found no effect of dispersal distance on post-settlement survival. Rather, survival was influenced by weather conditions, quality of the natal habitat patch, and a strong interaction between genotype and occupancy status of the settled habitat patch, with more mobile genotypes having higher survival as colonists rather than as immigrants. Our work highlights the multi-causality of dispersal and that some dispersal costs can only be understood by considering extrinsic and intrinsic factors and their interaction across the entire dispersal process.Peer reviewe

Organizational impact of evidence-informed decision making training initiatives : a case study comparison of two approaches

Background The impact of efforts by healthcare organizations to enhance the use of evidence to improve organizational processes through training programs has seldom been assessed. We therefore endeavored to assess whether and how the training of mid- and senior-level healthcare managers could lead to organizational change. Methods We conducted a theory-driven evaluation of the organizational impact of healthcare leaders’ participation in two training programs using a logic model based on Nonaka’s theory of knowledge conversion. We analyzed six case studies nested within the two programs using three embedded units of analysis (individual, group and organization). Interviews were conducted during intensive one-week data collection site visits. A total of 84 people were interviewed. Results We found that the impact of training could primarily be felt in trainees’ immediate work environments. The conversion of attitudes was found to be easier to achieve than the conversion of skills. Our results show that, although socialization and externalization were common in all cases, a lack of combination impeded the conversion of skills. We also identified several individual, organizational and program design factors that facilitated and/or impeded the dissemination of the attitudes and skills gained by trainees to other organizational members. Conclusions Our theory-driven evaluation showed that factors before, during and after training can influence the extent of skills and knowledge transfer. Our evaluation went further than previous research by revealing the influence—both positive and negative—of specific organizational factors on extending the impact of training programs

Hydrodynamical analysis of hadronic spectra in the 130 GeV/nucleon Au+Au collisions

We study one-particle spectra and a two-particle correlation function in the 130 GeV/nucleon Au+Au collisions at RHIC by making use of a hydrodynamical model. We calculate the one-particle hadronic spectra and present the first analysis of Bose-Einstein correlation functions based on the numerical solution of the hydrodynamical equations which takes both longitudinal and transverse expansion into account appropriately. The hydrodynamical model provides excellent agreement with the experimental data in the pseudorapidity and the transverse momentum spectra of charged hadrons, the rapidity dependence of anti-proton to proton ratio, and almost consistent result for the pion Bose-Einstein correlation functions. Our numerical solution with simple freeze-out picture suggests the formation of the quark-gluon plasma with large volume and low net-baryon density.Comment: 7 pages, 8 figures, REVTeX4. Numerical results and figures are correcte

Space-time evolution of bulk QCD matter

We introduce a combined fully three-dimensional macroscopic/microscopic transport approach employing relativistic 3D-hydrodynamics for the early, dense, deconfined stage of the reaction and a microscopic non-equilibrium model for the later hadronic stage where the equilibrium assumptions are not valid anymore. Within this approach we study the dynamics of hot, bulk QCD matter, which is being created in ultra-relativistic heavy ion collisions at RHIC. Our approach is capable of self-consistently calculating the freezeout of the hadronic system, while accounting for the collective flow on the hadronization hypersurface generated by the QGP expansion. In particular, we perform a detailed analysis of the reaction dynamics, hadronic freezeout, and transverse flow.Comment: 24 pages, 27 figure

Hydrodynamical evolution near the QCD critical end point

Hydrodynamical calculations have been successful in describing global observables in ultrarelativistic heavy ion collisions, which aim to observe the production of the quark-gluon plasma. On the other hand, recently, a lot of evidence that there exists a critical end point (CEP) in the QCD phase diagram has been accumulating. Nevertheless, so far, no equation of state with the CEP has been employed in hydrodynamical calculations. In this paper, we construct the equation of state with the CEP on the basis of the universality hypothesis and show that the CEP acts as an attractor of isentropic trajectories. We also consider the time evolution in the case with the CEP and discuss how the CEP affects the final state observables, such as the correlation length, fluctuation, chemical freezeout, kinetic freezeout, and so on. Finally, we argue that the anomalously low kinetic freezeout temperature at the BNL Relativistic Heavy Ion Collider suggests the possibility of the existence of the CEP.Comment: 13 pages, 12 figures, accepted for publication in Physical Review

Charmonium properties in hot quenched lattice QCD

We study the properties of charmonium states at finite temperature in quenched QCD on large and fine isotropic lattices. We perform a detailed analysis of charmonium correlation and spectral functions both below and above $T_c$. Our analysis suggests that both S wave states ($J/\psi$ and $\eta_c$) and P wave states ($\chi_{c0}$ and $\chi_{c1}$) disappear already at about $1.5 T_c$. The charm diffusion coefficient is estimated through the Kubo formula and found to be compatible with zero below $T_c$ and approximately $1/\pi T$ at $1.5 T_c\lesssim T\lesssim 3 T_c$.Comment: 32 pages, 19 figures, typo corrected, discussions on isotropic vs anisotropic lattices expanded, published versio