1,344 research outputs found
QCD dynamics in mesons at soft and hard scales
Using a ladder-rainbow kernel previously established for the soft scale of
light quark hadrons, we explore, within a Dyson-Schwinger approach, phenomena
that mix soft and hard scales of QCD. The difference between vector and axial
vector current correlators is examined to estimate the four quark chiral
condensate and the leading distance scale for the onset of non-perturbative
phenomena in QCD. The valence quark distributions, in the pion and kaon,
defined in deep inelastic scattering, and measured in the Drell Yan process,
are investigated with the same ladder-rainbow truncation of the Dyson-Schwinger
and Bethe-Salpeter equations.Comment: 6 pages, 1 double panel figure, invited talk presented at the
Workshop on Achievements and New Directions in Subatomic Physics, Adelaide,
Australia, February 2010, to be published by AIP Conf. Pro
Soft and Hard scale QCD Dynamics in Mesons
Using a ladder-rainbow kernel previously established for the soft scale of
light quark hadrons, we explore the extension to masses and electroweak decay
constants of ground state pseudoscalar and vector quarkonia and heavy-light
mesons in the c- and b-quark regions. We make a systematic study of the
effectiveness of a constituent mass concept as a replacement for a heavy quark
dressed propagator. The difference between vector and axial vector current
correlators is examined to estimate the four quark chiral condensate. The
valence quark distributions, in the pion and kaon, defined in deep inelastic
scattering, and measured in the Drell Yan process, are investigated with the
same ladder-rainbow truncation of the Dyson-Schwinger and Bethe-Salpeter
equations.Comment: 10 pages, 2 double panel figures, invited talk presented at the XII
Mexican Workshop on Particles and Fields, Mazatlan, Sinaloa, Mexico, November
2009; to be published by AIP Conf. Pro
Vietnam Inbound M&A Activity: the Role of Government Policy and Regulatory Environment
With a robust recent history of reform and opening, joining of the World Trade Organization, and negotiating a myriad of regional and global trade agreements, Vietnam has emerged as a promising destination for foreign direct investment(FDI) and cross-border mergers and acquisitions (M&A). In this paper, we providean overview of Vietnam’s inbound mergers and acquisitions and review the twomain driving forces of inbound M&A, which are the legal framework reformprocess and the equitization of State-owned enterprises. We close by providingdirections for future research in the area of cross-border M&As
Unexpected Dirac-Node Arc in the Topological Line-Node Semimetal HfSiS
We have performed angle-resolved photoemission spectroscopy on HfSiS, which
has been predicted to be a topological line-node semimetal with square Si
lattice. We found a quasi-two-dimensional Fermi surface hosting bulk nodal
lines, alongside the surface states at the Brillouin-zone corner exhibiting a
sizable Rashba splitting and band-mass renormalization due to many-body
interactions. Most notably, we discovered an unexpected Dirac-like dispersion
extending one-dimensionally in k space - the Dirac-node arc - near the bulk
node at the zone diagonal. These novel Dirac states reside on the surface and
could be related to hybridizations of bulk states, but currently we have no
explanation for its origin. This discovery poses an intriguing challenge to the
theoretical understanding of topological line-node semimetals.Comment: 5 pages, 4 figures (paper proper) + 2 pages, figures (supplemental
material
Towards a Taxonomy of Information Security Policy Non-Compliance Behavior
Due to the increasing digitalization of our society, IT security professionals must implement even more effective security measures to meet the growing information security requirements of their organizations. To target and effectively deploy these measures in the best possible way, they must consider different types of behaviors that might lead to information security threats. Regarding this issue, current research offers little for clarity to security professionals when it comes to understanding and differentiating the various types of behavior. Therefore, this research aims to develop a taxonomy to classify different types of information security policy non-compliance behavior. Our results present a taxonomy with five dimensions, each containing mutually exclusive and collectively exhaustive characteristics. Our results provide a basis for a more specific analysis of different types of information security policy non-compliance behavior and can be used for more comprehensive development and analysis of appropriate security measures
Spotlight Attention: Robust Object-Centric Learning With a Spatial Locality Prior
The aim of object-centric vision is to construct an explicit representation
of the objects in a scene. This representation is obtained via a set of
interchangeable modules called \emph{slots} or \emph{object files} that compete
for local patches of an image. The competition has a weak inductive bias to
preserve spatial continuity; consequently, one slot may claim patches scattered
diffusely throughout the image. In contrast, the inductive bias of human vision
is strong, to the degree that attention has classically been described with a
spotlight metaphor. We incorporate a spatial-locality prior into
state-of-the-art object-centric vision models and obtain significant
improvements in segmenting objects in both synthetic and real-world datasets.
Similar to human visual attention, the combination of image content and spatial
constraints yield robust unsupervised object-centric learning, including less
sensitivity to model hyperparameters.Comment: 16 pages, 3 figures, under review at NeurIPS 202
Chasing Cyber Security Unicorns: A Taxonomy-based Analysis of Cyber Security Start-ups’ Business Models
As the number of security incidents increases, a market is emerging for established and new providers of security measures. However, we lack an idea of the business models of cyber security start-ups, which are seen as innovation and security drivers, to protect the economy from existence-threatening incidents. Due to the intangible nature of the cyber threats that security solutions aim to address, previous research on business models cannot be fully transferred. We address this research gap by developing a taxonomy following Nickerson et al. (2013) based on 90 cyber security start-ups and performing a cluster analysis to understand the business activities of cyber security start-ups concerning the protection of critical infrastructures. Our taxonomy will benefit interested decision-makers such as CISOs who want to identify custom-fit cyber security solutions for their organizations. Furthermore, investors and cyber security providers understand the market holistically and can identify innovative product approaches to adopt themselves
Modeling of Interstellar Scintillation Arcs from Pulsar B1133+16
The parabolic arc phenomenon visible in the Fourier analysis of the
scintillation spectra of pulsars provides a new method of investigating the
small scale structure in the ionized interstellar medium (ISM). We report
archival observations of the pulsar B1133+16 showing both forward and reverse
parabolic arcs sampled over 14 months. These features can be understood as the
mutual interference between an assembly of discrete features in the scattered
brightness distribution. By model-fitting to the observed arcs at one epoch we
obtain a ``snap-shot'' estimate of the scattered brightness, which we show to
be highly anisotropic (axial ratio >10:1), to be centered significantly off
axis and to have a small number of discrete maxima, which are coarser the
speckle expected from a Kolmogorov spectrum of interstellar plasma density. The
results suggest the effects of highly localized discrete scattering regions
which subtend 0.1-1 mas, but can scatter (or refract) the radiation by angles
that are five or more times larger.Comment: 14 pages, 4 figures, submitted to Astrophysical Journa
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