Momentum Correlations of Charmed Pairs Produced in π−−Cu\pi^{-}-Cu Interactions at 230 GeV/c

We study the production characteristics of 557 pairs of charmed hadrons produced in $\pi^{-}-Cu$\ interactions at 230~GeV/c using a momentum estimator for charmed hadrons with missing decay products. We find, the mean value of the transverse momentum squared of the charmed pairs is $=(1.98\pm 0.11\pm 0.09)\;$ GeV$^2$/c$^2$, the mean rapidity difference is $=0.54\pm 0.02\pm 0.24$, and the mean effective mass is $=(4.45\pm 0.03\pm 0.13)\;$ GeV/c$^2$. Comparing these results with the next-to-leading order QCD predictions we find an agreement for the \yd\ and \mef, whilst the measured mean value of \pts\ is significantly larger than the predicted value.Comment: 10 pages, LaTeX, 4 (pages) postscript figure

A Logical Characterization of Constant-Depth Circuits over the Reals

In this paper we give an Immerman's Theorem for real-valued computation. We define circuits operating over real numbers and show that families of such circuits of polynomial size and constant depth decide exactly those sets of vectors of reals that can be defined in first-order logic on R-structures in the sense of Cucker and Meer. Our characterization holds both non-uniformily as well as for many natural uniformity conditions.Comment: 24 pages, submitted to WoLLIC 202

Calorimetric and thermogravimetric study on the influence of calcium sulfate on the hydration of ye'elimite

Calcium sulfoaluminate (CSA) cements, which represent a CO2-friendly alternative to conventional Portland cements, are produced by blending CSA clinker with gypsum and/or anhydrite. The hydration kinetics and the hydrated phase assemblages of the main hydraulic phase ye'elimite (calcium sulfoaluminate) with calcium sulfate were studied by isothermal conduction calorimetry, thermogravimetric analysis, X-ray diffraction analysis and thermodynamic modelling. Two calcium sulfates with different reactivities (gypsum and anhydrite) were applied. It was found that the pure phase without any calcium sulfate addition exhibits very slow hydration kinetics during the first 10h. The hydration can be accelerated by the addition of calcium sulfate or (less effective) by increasing the pH of the aqueous phase. The amount of the calcium sulfate determines the ratio between the hydration products ettringite, monosulfate and amorphous aluminium hydroxide. The reactivity of the added calcium sulfate determines the early hydration kinetics. It was found that the more reactive gypsum was better suited to control the hydration behaviour of ye'elimit

OPEN CHARM PRODUCTION IN HADRONIC AND HEAVY-ION COLLISIONS AT RHIC AND LHC ENERGIES TO O(αs3)O(\alpha_s^3)

We present results on rapidity and transverse momentum distributions of inclusive charm quark production in hadronic and heavy-ion collisions at RHIC and LHC energies, including the next-to-leading order, $O(\alpha_s^3)$, radiative corrections and the nuclear shadowing effect. We determine the hadronic and the {\it effective} (in-medium) K-factor for the differential and total inclusive charm cross sections. We show that these K-factors have strong $p_T$ dependence. We discuss how measurements of charm production at RHIC and LHC can provide valuable information about the gluon density in a nucleus.Comment: LaTex, 4 pages, 2 figs (available on request) Talk presented at Eleventh International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions -- Quark Matter '95, Monterey, CA, January 9-13, 1995

On three-body B decays to charm

I briefly describe the use of the three-body decay modes $B^0 \to D^{(*)-} D^{(*)0} K^+$ to investigate open issues in charmed meson spectroscopy, and of the time dependent $B^0 (\bar {B^0}) (t) \to D^{-} D^{+} \pi^0$ transitions for a measurement of $\cos (2 \beta)$.Comment: LaTeX, 4 pages, 4 figs. Talk at 5th International Conference on Hyperons, Charm and Beauty Hadrons (BEACH 2002), Vancouver, Canada, 25-29 Jun 200

Measures against heat stress in the city of Gelsenkirchen, Germany

In the near-surface atmosphere, heat waves during the summer cause situations that may lead to human-biometeo-rological impairment. Because of their high population density, overheated cities are particularly strongly affected by heat stress. In the future, due to the effects of climate change, heat stress will increase in terms of its intensity and spatial expansion in the areas of concern. Taking the example of the city of Gelsenkirchen, Germany, this article presents a method for the identification of areas requiring adaptation or protection. A scenario of the future increase of heat stress events is presented, based on data of the German climate change model STAR II. For the identification of areas requiring adaptation and protection, spatial analyses of the urban heat island, land use and demographic aspects were performed using GIS tools. The application and assessment of adaptation measures is investigated for an urban quarter using the microscale numerical model ENVI-met. Finally adaptation measures in urban planning against heat stress are discussed. The relevant urban planning adaptation measures, which are also important in view of climate change, not only involve heat stress reduction in the residential areas already affected, but also in-volve the protection and optimisation of existing favourable and compensation areas

Unified Foundations of Team Semantics via Semirings

Semiring semantics for first-order logic provides a way to trace how facts represented by a model are used to deduce satisfaction of a formula. Team semantics is a framework for studying logics of dependence and independence in diverse contexts such as databases, quantum mechanics, and statistics by extending first-order logic with atoms that describe dependencies between variables. Combining these two, we propose a unifying approach for analysing the concepts of dependence and independence via a novel semiring team semantics, which subsumes all the previously considered variants for first-order team semantics. In particular, we study the preservation of satisfaction of dependencies and formulae between different semirings. In addition we create links to reasoning tasks such as provenance, counting, and repairs

Chiral Perturbation Theory for B→D∗B \rightarrow D^* and B→DB \rightarrow D Semileptonic Transition Matrix Elements at Zero Recoil

Heavy quark symmetry predicts the value of $B \rightarrow D$ and $B \rightarrow D^*$ transition matrix elements of the current $\bar c \gamma_\mu (1 - \gamma_5)b$, at zero recoil (where in the rest frame of the $B$ the $D$ or $D^*$ is also at rest). We use chiral perturbation theory to compute the leading corrections to these predictions which are generated at low momentum, below the chiral symmetry breaking scale.Comment: 10 pages, 1 figure (not included), CALT-68-1844, MIT-CTP-217

Open charm production in relativistic nucleus-nucleus collisions

We calculate excitation functions for open charm mesons in $Au+Au$ reactions from AGS to RHIC energies within the HSD transport approach which is based on string, quark, diquark ($q, \bar{q}, qq, \bar{q}\bar{q}$) and hadronic degrees of freedom. The open charm cross sections from $pN$ and $\pi N$ reactions are fitted to results from PYTHIA and scaled in magnitude to the available experimental data. From our dynamical calculations we find an approximate $m_T$-scaling for pions, kaons, $D$-mesons and $J/\Psi$ -- when discarding final state elastic scattering of kaons and $\phi$-mesons with pions -- in central collisions of $Au + Au$ at 160 A$\cdot$GeV (with an apparent slope of 176 MeV) without employing the assumption of a Quark-Gluon Plasma (QGP). We demonstrate that this result is essentially due to a relative $m_T$-scaling in $pp$ collisions at $\sqrt{s} \approx$ 17.3 GeV. At lower bombarding energies of 25 A$\cdot$GeV a suppression of $D$-mesons by a factor of $\sim$ 10 relative to a global $m_T$-scaling with slope 143 MeV is expected. However, when incorporating attractive $D$-meson self energies as suggested by QCD sum rules, an approximate $m_T$-scaling is regained even at 25 A$\cdot$GeV. The effects of $D$-meson rescattering and charmonium absorption are discussed, furthermore, with respect to rapidity and transverse mass distributions in central collisions of $Au + Au$ at 25, 160 A$\cdot$GeV and 21.3 A$\cdot$TeV.Comment: 46 pages, LaTeX, including 19 postscript figures, to be published in Nucl. Phys.