1,369 research outputs found

    Can Recent Charge Fluctuations Be a Reliable signal for a QGP at RHIC?

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    The recent papers of Jeon and Koch [1] and Asakawa, Heinz, and Muller [2] argue that the event by event fluctuations of the ratio of the positively charged and negatively charged pions provide a distinct signal for a QGP at RHIC/LHC due to differences in those from the QGP phase and the Hadron Gas Phase.In this paper we point out that aside from the questionability of the many assumptions in the treatment used,even following their approach there are other effects not considered, e.g. color charge fluctuations, which could significantly or even completely wash out the proposed signal.Therefore lack of observation of these charge fluctuation signals cannot lead one to conclude that a QGP is not formed at RHIC. A general discussion of experimental requirements for observation of such signals(if they exist),annd how to interpret them is included.Comment: 9 pages and 2 Fig

    Evidence for a 4th state related to the three JPC = 2++, pi- p -> phi phi n states explainable by 2++ Glueball production

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    Four separate experiments, observing the OZI forbidden disconnected reaction pi- p -> phi phi n with increasing statistics were consistent. These experiments very selectively completely broke down the OZI suppression by 3 phi phi resonances with IG JPC = 0+ 2++ in the observed mass region 2.038 to 2.600 GeV. The only viable proposed explanation has been that the IG JPC = 0+ 2++ Glueball expected in this mass region caused the hard glue in the disconnection to resonate and very selectively breakdown the OZI suppression for its quantum numbers only. Recently a p p central production spin analysis found the f2(1950) had a dominant decay mode f2(1270) pi pi. We consider if it is related to the phi phi resonances, and find that it likely is.Comment: 9 pages, 3 figure

    The Centrality Dependence of the Parton Bubble Model for high energy heavy ion collisions and fireball surface substructure at RHIC

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    In an earlier paper we developed a QCD inspired theoretical parton bubble model (PBM) for RHIC/LHC. The PBM quantitatively agreed with the strong charged particle pair correlations observed by the STAR collaboration at RHIC in the highest energy Au + Au central collisions, and also agreed with the Hanbury Brown and Twiss (HBT) observed small final state source size approximately 2f radii in the transverse momentum range above 0.8 GeV/c. The model assumed a substructure of a ring of localized adjoining 2f radius bubbles(gluonic hot spots) perpendicular to the collider beam direction, centered on the beam, at mid-rapidity and located on the expanding fireball surface of the Au + Au collisions. In this paper we extend the model (PBME) to include the changing development of bubbles with centrality from the most central region where bubbles are very important to the most peripheral where the bubbles are gone. Energy density is found to be related to bubble formation and as centrality decreases the maximum energy density and bubbles shift from symmetry around the beam axis to the reaction plane region causing a strong correlation of bubble formation with elliptic flow. We obtained reasonably quantitative agreement (within a few percent of the total correlations) with a new precision RHIC experiment which extended the centrality region investigated to the range 0-80% (most central to most peripheral). The characteristics and behavior of the bubbles imply they represent a significant substructure formed on the surface of the fireball at kinetic freezeoutComment: ACCEPTED for publication in Phys. Rev. C. minor referee changes.20 pages, 12 figures, 3 table

    HIGH ENERGY ELASTIC SCATTERING OF pipisup1sup 1, p,/anti p/ AND Ksup1sup 1 BY PROTONS (AND REGGE POLE PREDICTIONS)

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    The counter hodoscope experiments at incident particle momenta of 7-20 Bev/c are summarized. The data are presented, together with the associated Regge pole analyses. The effective radii, opacities, and total cross sections obtained for the interactions are included. A magnetic spectrometer setup used for low four-momentum transfer data is also described, and optical theorem predictions for pi /sup -/-p and p-p are given. (D.C.W.

    Exploring a rheonomic system

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    A simple and illustrative rheonomic system is explored in the Lagrangian formalism. The difference between Jacobi's integral and energy is highlighted. A sharp contrast with remarks found in the literature is pointed out. The non-conservative system possess a Lagrangian not explicitly dependent on time and consequently there is a Jacobi's integral. The Lagrange undetermined multiplier method is used as a complement to obtain a few interesting conclusion

    Turboprop cargo aircraft systems study

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    The effects of using advanced turboprop propulsion systems to reduce the fuel consumption and direct operating costs of cargo aircraft were studied, and the impact of these systems on aircraft noise and noise prints around a terminal area was determined. Parametric variations of aircraft and propeller characteristics were investigated to determine their effects on noiseprint areas, fuel consumption, and direct operating costs. From these results, three aircraft designs were selected and subjected to design refinements and sensitivity analyses. Three competitive turbofan aircraft were also defined from parametric studies to provide a basis for comparing the two types of propulsion

    Coupling Constants for Scalar Glueball Decay

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    We evaluate the partial decay widths of the lightest scalar glueball to pairs of pseudoscalar quark-antiquark states. The calculation is done in the valence (quenched) approximation on a 16^3 \time 24 lattice at β=5.7\beta = 5.7. These predictions and values obtained earlier for the infinite volume continuum limit of the scalar glueball's mass are in good agreement with the observed properties of fJ(1710)f_J(1710) and inconsistent with all other observed meson resonances.Comment: 8 pages of Latex, 12 PostScript figures, 2 macros included, plenary talk given by D. Weingarten at Lattice 95, to appear in conference proceeding

    Turboprop Cargo Aircraft Systems study, phase 1

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    The effects of advanced propellers (propfan) on aircraft direct operating costs, fuel consumption, and noiseprints were determined. A comparison of three aircraft selected from the results with competitive turbofan aircraft shows that advanced turboprop aircraft offer these potential benefits, relative to advanced turbofan aircraft: 21 percent fuel saving, 26 percent higher fuel efficiency, 15 percent lower DOCs, and 25 percent shorter field lengths. Fuel consumption for the turboprop is nearly 40 percent less than for current commercial turbofan aircraft. Aircraft with both types of propulsion satisfy current federal noise regulations. Advanced turboprop aircraft have smaller noiseprints at 90 EPNdB than advanced turbofan aircraft, but large noiseprints at 70 and 80 EPNdB levels, which are usually suggested as quietness goals. Accelerated development of advanced turboprops is strongly recommended to permit early attainment of the potential fuel saving. Several areas of work are identified which may produce quieter turboprop aircraft
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