33 research outputs found
Photoproduction evidence for and against hidden-strangeness states near 2 GeV
Experimental evidence from coherent diffractive proton scattering has been
reported for two narrow baryonic resonances which decay predominantly to
strange particles. These states, with masses close to 2.0 GeV would, if
confirmed, be candidates for hidden strangeness states with unusual internal
structure. In this paper we examine the literature on strangeness
photoproduction, to seek additional evidence for or against these states. We
find that one state is not confirmed, while for the other state there is some
mild supporting evidence favoring its existence. New experiments are called
for, and the expected photoproduction lineshapes are calculated.Comment: 9 pages, RevTex, five postscript figures, submitted to PR
Flavor SU(3) breaking effects in the chiral unitary model for meson-baryon scatterings
We examine flavor SU(3) breaking effects on meson-baryon scattering
amplitudes in the chiral unitary model. It turns out that the SU(3) breaking,
which appears in the leading quark mass term in the chiral expansion, can not
explain the channel dependence of the subtraction parameters of the model,
which are crucial to reproduce the observed scattering amplitudes and resonance
properties.Comment: RevTeX4, 4 pages, 3 figures, 2 table
Photon- and meson-induced reactions on the nucleon
In an unitary effective Lagrangian model we develop a unified description of
both meson scattering and photon-induced reactions on the nucleon. Adding the
photon to an already existing model for meson-nucleon scattering yields both
Compton and meson photoproduction amplitudes. In a simultaneous fit to all
available data involving the final states , , ,
and the parameters of the nucleon resonances are
extracted.Comment: 57 pages, 14 figures, LaTex (uses Revtex and graphicx). Submitted to
Phys. Rev. C. References updated, Fig. 14 change
Vector meson production and nucleon resonance analysis in a coupled-channel approach for energies m_N < sqrt(s) < 2 GeV II: photon-induced results
We present a nucleon resonance analysis by simultaneously considering all
pion- and photon-induced experimental data on the final states gamma N, pi N, 2
pi N, eta N, K Lambda, K Sigma, and omega N for energies from the nucleon mass
up to sqrt(s) = 2 GeV. In this analysis we find strong evidence for the
resonances P_{31}(1750), P_{13}(1900), P_{33}(1920), and D_{13}(1950). The
omega N production mechanism is dominated by large P_{11}(1710) and
P_{13}(1900) contributions. In this second part we present the results on the
photoproduction reactions and the electromagnetic properties of the resonances.
The inclusion of all important final states up to sqrt(s) = 2 GeV allows for
estimates on the importance of the individual states for the GDH sum rule.Comment: 41 pages, 26 figures, discussion extended, typos corrected,
references updated, to appear in Phys. Rev.
Non-intersecting squared Bessel paths at a hard-edge tacnode
The squared Bessel process is a 1-dimensional diffusion process related to
the squared norm of a higher dimensional Brownian motion. We study a model of
non-intersecting squared Bessel paths, with all paths starting at the same
point at time and ending at the same point at time . Our
interest lies in the critical regime , for which the paths are tangent
to the hard edge at the origin at a critical time . The critical
behavior of the paths for is studied in a scaling limit with time
and temperature . This leads to a critical
correlation kernel that is defined via a new Riemann-Hilbert problem of size
. The Riemann-Hilbert problem gives rise to a new Lax pair
representation for the Hastings-McLeod solution to the inhomogeneous Painlev\'e
II equation where with
the parameter of the squared Bessel process. These results extend
our recent work with Kuijlaars and Zhang \cite{DKZ} for the homogeneous case
.Comment: 54 pages, 13 figures. Corrected error in Theorem 2.
ENTERPRISE SOCIAL MEDIA MODERATION AND USER GENERATED CONTENT QUALITY: A CRITICAL DISCUSSION AND NEW INSIGHTS
Social network platforms in enterprises are an increasingly important phenomenon. Thus, the participation and content generation of users are critical aspects of the sustainable use of these enterprise social media (ESM) services. However, at the same time, organizations need to ensure the quality of user-generated content (UGC), which remains a challenge for ESM moderation. In this structured literature review, we investigate measures to identify high-quality UGC and organizational approaches to promote such UGC. We categorize our findings as textual-, content appraisal, network- and author-based measures. We follow up by assigning each measure to a motivation and localization approach. We reflect on opportunities to transfer public social media measures into an ESM environment. We conclude our examination of UGC quality by integrating the UGC quality dimension into an ESM moderation framework and by outlining implications for research and practice