Dilepton yields from Brown-Rho scaled vector mesons including memory effects

Brown-Rho scaling, which has been strongly discussed after recent NA60 data was presented, is investigated within a nonequilibrium field theoretical description that includes quantum mechanical memory. Dimuon yields are calculated by application of a model for the fireball, and strong modifications are found in the comparison to quasi-equilibrium calculations, which assume instantaneous adjustment of all meson properties to the surrounding medium. In addition, we show results for the situation of very broad excitations.Comment: 4 pages, 5 figure

The Bender Visual-Motor Gestalt Test as a Measure of Aggression in Children

The Bender-Gestalt Test has been routinely used for the past two years at the Annie Wittenmyer Home, an institution for dependent and neglected children in Iowa. This simple test was first designed by Bender (1938), as a performance test for young children. Her manual also indicates that the test can be used in the differentiation of organic brain anomolies, schizophrenias and psychoneuroses. This area of research has been covered by Hutt (1945) Swenson and Pascal (1953), Guertin (1954), and others. The observations of the writers have indicated that there is a wide difference in the way apparently normal children respond to these designs. These differences have heretofore been interpreted in the light of Hutt\u27s (1945) findings with an adult population. For example, he indicated that such things as diminution of the figures, conservation of space and the use of light pressure in drawing are indicative of social withdrawal, limited activity and unassertiveness. In another article Hutt (1953) stated that, aggressive and rebellious individuals usually show an excessive use of space. On the other hand an inordinately small amount of space between successive drawings is indicative of repressed hostility, occasionally turned inwards in the form of masochistic strivings or needs. Peek (1953) has shown that the direction of drawing a single line such as the diagonal on the figure 5 (an incomplete circle with an intersecting slanting line both composed of dots) can be indicative of differences in personality adjustment. He found that patients drawing the diagonal toward the half-circle rather than in the popular direction, i.e., away from the halfcircle were significantly more immature and dependent than the control group. Rather than being able to direct their hostility upon the sources of their frustration they were inclined to use less adaptive mechanisms such as headaches and other somatic complaints. They were therefore more apt to build up frustrations which spill over into poorly controlled and indirect forms of aggressive hostility

Dilepton production from non-equilibrium hot hadronic matter

It is investigated under which conditions an adiabatic adaption of the dynamic and spectral information of vector mesons to the changing medium in heavy ion collisions, as assumed in schematic model calculations and microscopic transport simulations, is a valid assumption. Therefore time dependent medium modifications of low mass vector mesons are studied within a non-equilibrium quantum field theoretical description. Timescales for the adaption of the spectral properties are given and non-equilibrium dilepton yields are calculated, leading to the result that memory effects are not negligible for most scenarios.Comment: 6 pages, 4 figures, To appear in the proceedings of the 43rd International Winter Meeting on Nuclear Physics, Bormio, Italy, 13 Mar - 20 Mar 200

Search for a Ridge Structure Origin with Shower Broadening and Jet Quenching

We investigate the role of jet and shower parton broadening by the strong colour field in the $\Delta\eta$-$\Delta\phi$ correlation of high $p_T$ particles. When anisotropic momentum broadening ($\Delta p_z > \Delta p_T$) is given to jet and shower partons in the initial stage, a ridge-like structure is found to appear in the two hadron correlation. The ratio of the peak to the pedestal yield is overestimated.Comment: Talk given at 20th Int. Conf. on Ultra-Relativistic Nucleus-Nucleus Collisions, Jaipur, India, Feb.4-10, 200

Thermalization and the chromo-Weibel instability

Despite the apparent success of ideal hydrodynamics in describing the elliptic flow data which have been produced at Brookhaven National Lab's Relativistic Heavy Ion Collider, one lingering question remains: is the use of ideal hydrodynamics at times t < 1 fm/c justified? In order to justify its use a method for rapidly producing isotropic thermal matter at RHIC energies is required. One of the chief obstacles to early isotropization/thermalization is the rapid longitudinal expansion of the matter during the earliest times after the initial nuclear impact. As a result of this expansion the parton distribution functions become locally anisotropic in momentum space. In contrast to locally isotropic plasmas anisotropic plasmas have a spectrum of soft unstable modes which are characterized by exponential growth of transverse chromo-magnetic/-electric fields at short times. This instability is the QCD analogue of the Weibel instability of QED. Parametrically the chromo-Weibel instability provides the fastest method for generation of soft background fields and dominates the short-time dynamics of the system.Comment: 8 pages, 4 figures, Invited plenary talk given at the 19th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions: Quark Matter 2006 (QM 2006), Shanghai, China, 14-20 Nov 200

Resource requirements for the implementation of a global H2-powered aviation

In this paper, the resource requirements for the implementation of global H2-powered aviation are investigated to answer one of the main questions asked by many stakeholders in the aviation industry: Are there any resource limitations for the implementation of H2-powered aviation on a global scale? For this, the raw material, renewable energy and water demands for the deployment and operational phase are investigated on a global and regional perspective. It is found that the iridium demand for a global hydrogen economy could be critical as it would exceed not only the current annual production by a factor of 11 but also the current reserves about 1.7 times. The H2-powered aviation alone is not the main driver of iridium demand but could increase the limitations. With reduced specific raw material demands of further optimized electrolysis technologies and increased annual raw material production, the limitations especially for the iridium demand could be overcome. Renewable energy capacities and water availability are sufficient for demands from H2-powered aircraft on a global perspective. Nevertheless, the limited availability of renewable energy sources in some regions and regional water constraints may necessitate hydrogen import for certain airports. While water desalination is likely to overcome water constraints in regions close to the sea, for airports located in regions with detrimental availability of renewable energy sources the import of hydrogen is the only way to ensure a hydrogen supply for H2-powered aviation

H2-powered aviation – Design and economics of green LH2 supply for airports

The economic competitiveness of hydrogen-powered aviation highly depends on the supply costs of green liquid hydrogen to enable true-zero CO2 flying. This study uses non-linear energy system optimization to analyze three main liquid hydrogen (LH2) supply pathways for five locations. Final liquid hydrogen costs at the dispenser supply costs could reach 2.04 USD/kgLH2 in a 2050 base case scenario for locations with strong renewable energy source conditions. This could lead to cost-competitive flying with hydrogen. Reflecting techno-economic uncertainties in two additional scenarios, the liquid hydrogen cost span at all five airport locations ranges between 1.37–3.48 USD/kgLH2, if hydrogen import options from larger hydrogen markets are also available. Import setups are of special importance for airports with a weaker renewable energy source situation, e.g., selected Central European airports. There, on-site supply might not only be too expensive, but space requirements for renewable energy sources could be too large for feasible implementation in densely populated regions. Furthermore, main costs for liquid hydrogen are caused by renewable energy sources, electrolysis systems, and liquefaction plants. Seven detailed design rules are derived for optimized energy systems for these and the storage components. This and the cost results should help infrastructure planners and general industry and policy players prioritize research and development needs

Locally anisotropic momentum distributions of hadrons at freeze-out in relativistic heavy-ion collisions

A spheroidal anisotropic local momentum distribution is implemented in the statistical model of hadron production. We show that this form leads to exactly the same ratios of hadronic abundances as the equilibrium distributions, if the temperature is identified with a characteristic transverse-momentum scale. Moreover, to a very good approximation the transverse-momentum spectra of hadrons are the same for isotropic and anisotropic systems, provided the size of the system at freeze-out is appropriately adjusted. We further show that this invariance may be used to improve the agreement between the model and experimental HBT results.Comment: 7 pages, 4 figure