5,277 research outputs found
Estimates of production rates of SUSY particles in ultra-relativistic heavy-ion collisions
We estimate the production rates of supersymmetric particles in central
heavy-ion collisions at LHC. The parton cascade model is used to seek for
possible collective phenomena which enlarge the production probability of very
heavy particles. Even if there is some indication of such cooperative effects,
higher energy and higher luminosity of proton beams at LHC disfavor heavy-ion
reactions in the search for supersymmetric particles.Comment: 19 pages including 10 EPS figure
Analysis of reaction dynamics at RHIC in a combined parton/hadron transport approach
We introduce a transport approach which combines partonic and hadronic
degrees of freedom on an equal footing and discuss the resulting reaction
dynamics. The initial parton dynamics is modeled in the framework of the parton
cascade model, hadronization is performed via a cluster hadronization model and
configuration space coalescence, and the hadronic phase is described by a
microscopic hadronic transport approach. The resulting reaction dynamics
indicates a strong influence of hadronic rescattering on the space-time pattern
of hadronic freeze-out and on the shape of transverse mass spectra. Freeze-out
times and transverse radii increase by factors of 2 - 3 depending on the hadron
species.Comment: 10 pages, 4 eps figures include
Entwicklung von Maissorten mit spezieller Anpassung an die Bedingungen des Ăkologischen Landbaus
Organic farming has gained in importance in Germany during the past years. Therefore an increasing demand exists for varieties with specific adaptation to this farming system. Hence it becomes necessary for plant breeders to optimize their selection strategy for varieties which meet the requirements of organic farming. For this purpose a research project was conducted at the University of Hohenheim, Institute of Plant Breeding, Seed Science, and Population Genetics in cooperation with the KWS SAAT AG. It was supported by the âBundesprogramm Ăkologischer Landbauâ and lasted from April 2004 to December 2006. In the present contribution the results of comparative trials with maize under organic and conventional farming conditions in 2004 and 2005 are reported. It is demonstrated that under organic farming maize genotypes can be evaluated with similar precision as under conventional conditions. However, inconsistent correlations between the two farming systems indicate that the predictability of performance under organic farming from data obtained under conventional farming and vice versa strongly depends on the genetic materials
Heavy resonance production in high energy nuclear collisions
We estimate freezeout conditions for , , and quarks in high energy
nuclear collisions. Freezeout is due either to loss of thermal contact, or to
particles ``wandering'' out of the region of hot matter. We then develop a
thermal recombination model in which both single-particle (quark and antiquark)
and two-particle (quark-antiquark) densities are conserved. Conservation of
two-particle densities is necessary because quarks and antiquarks are always
produced in coincidence, so that the local two-particle density can be much
larger than the product of the single-particle densities. We use the freezeout
conditions and recombination model to discuss heavy resonance production at
zero baryon density in high energy nuclear collisions.Comment: revtex, 15 pages, no figures, KSUCNR-009-9
What Does an Exemplary Middle School Mathematics Teacher Look Like? The Use of a Professional Development Rubric
A School University Research Network (SURN) committee composed of current mathematics teachers, central ofïŹce math supervisors, building administrators, mathematicians, and mathematics educators researched numerous sources regarding best practices in mathematics instruction. The resulting professional development rubric synthesizes their findings and can serve a professional development role by providing teachers and administrators with a tool to develop clarity and consensus on best mathematics instructional practices, and how these practices are implemented in the classroom. It is also being used as a tool for cooperating teachers in their supervision of student teachers and as a reïŹective method for self-evaluation
Deep-Inelastic Final States in a Space-Time Description of Shower Development and Hadronization
We extend a quantum kinetic approach to the description of hadronic showers
in space, time and momentum space to deep-inelastic collisions, with
particular reference to experiments at HERA. We follow the history of hard
scattering events back to the initial hadronic state and forward to the
formation of colour-singlet pre-hadronic clusters and their decays into
hadrons. The time evolution of the space-like initial-state shower and the
time-like secondary partons are treated similarly, and cluster formation is
treated using a spatial criterion motivated by confinement and a
non-perturbative model for hadronization. We calculate the time evolution of
particle distributions in rapidity, transverse and longitudinal space. We also
compare the transverse hadronic energy flow and the distribution of observed
hadronic masses with experimental data from HERA, and find encouraging results.
The techniques developed in this paper may be applied in the future to more
complicated processes such as eA, pp, pA and AA collisions.Comment: 44 pages plus 14 postscript figure
On the Consistency of the Exact Renormalization Group Approach Applied to Gauge Theories in Algebraic Non-Covariant Gauges
We study a class of Wilsonian formulations of non-Abelian gauge theories in
algebraic non-covariant gauges where the Wilsonian infrared cutoff is
inserted as a mass term for the propagating fields. In this way the
Ward-Takahashi identities are preserved to all scales. Nevertheless
BRST-invariance in broken and the theory is gauge-dependent and unphysical at
. Then we discuss the infrared limit . We show that
the singularities of the axial gauge choice are avoided in planar gauge and
light-cone gauge. In addition the issue of infrared divergences is addressed in
some explicit example. Finally the rectangular Wilson loop of size is evaluated at lowest order in perturbation theory and a non commutativity
between the limits and is pointed out.Comment: Latex2e, 49 pages, 2 EPS figures. Misprints corrected. Version to be
published on IJMP
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