994 research outputs found
Non-strange light-meson spectroscopy at COMPASS
Lattice-QCD predicts the exotic meson to dominantly decay to
. The decay channel is accessible via the
final state. COMPASS recorded the so far largest data
set of this final state. A partial-wave analysis allows to determine the
resonant content in this final state including possible contributions from
. Decomposing the measured intensity into amplitudes of partial
waves gives a first qualitative insight into contributing intermediate states.
We observe signals in agreement with well-established states like the
and . Smaller resonance-like signals are visible in the
sectors and , where possible states were claimed but
none are established. For a signal at
in partial waves is consistent with
the expected .Comment: 5 pages, 3 figures, talk presented at 20th International Conference
on Hadron Spectroscopy and Structure (HADRON 2023) in Genova, Italy, June 5th
to 9th 202
A magnetar engine for short GRBs and kilonovae
We investigate the influence of magnetic fields on the evolution of binary
neutron-star (BNS) merger remnants via three-dimensional (3D)
dynamical-spacetime general-relativistic (GR) magnetohydrodynamic (MHD)
simulations. We evolve a postmerger remnant with an initial poloidal magnetic
field, resolve the magnetoturbulence driven by shear flows, and include a
microphysical finite-temperature equation of state (EOS). A neutrino leakage
scheme that captures the overall energetics and lepton number exchange is also
included. We find that turbulence induced by the magnetorotational instability
(MRI) in the hypermassive neutron star (HMNS) amplifies magnetic field to
beyond magnetar-strength (). The ultra-strong toroidal
field is able to launch a relativistic jet from the HMNS. We also find a
magnetized wind that ejects neutron-rich material with a rate of
.
The total ejecta mass in our simulation is . This makes the ejecta from the HMNS an important component
in BNS mergers and a promising source of -process elements that can power a
kilonova. The jet from the HMNS reaches a terminal Lorentz factor of
in our highest-resolution simulation. The formation of this jet is aided by
neutrino-cooling preventing the accretion disk from protruding into the polar
region. As neutrino pair-annihilation and radiative processes in the jet (which
were not included in the simulations) will boost the Lorentz factor in the jet
further, our simulations demonstrate that magnetars formed in BNS mergers are a
viable engine for short gamma-ray bursts (sGRBs).Comment: Resubmitted versio
Blueprinting Crowdfunding - Designing a Crowdfunding Service Configuration Framework
Crowdfunding gained momentum over the last few years. In contrast to traditional forms of funding, the service provision of crowdfunding platforms is performed within service systems. These comprise a complex combination of IT and non-IT services, different stakeholders, and diverging contexts and purposes. The design and operation of such service systems represents a tough challenge. Therefore, we developed a crowdfunding service configuration framework in the form of a morphological box and derived three dominant design patterns by following a design science approach. Therefore, we followed three iterations, which comprise in total twelve expert interviews, three case studies and the analysis of 161 crowdfunding platforms. The configuration framework extends research on crowdfunding and service science by providing insights in how to support the systematic design of crowdfunding service systems, reducing their complexity, and giving a comprehensive overview over their building blocks
IllinoisGRMHD: An Open-Source, User-Friendly GRMHD Code for Dynamical Spacetimes
In the extreme violence of merger and mass accretion, compact objects like
black holes and neutron stars are thought to launch some of the most luminous
outbursts of electromagnetic and gravitational wave energy in the Universe.
Modeling these systems realistically is a central problem in theoretical
astrophysics, but has proven extremely challenging, requiring the development
of numerical relativity codes that solve Einstein's equations for the
spacetime, coupled to the equations of general relativistic (ideal)
magnetohydrodynamics (GRMHD) for the magnetized fluids. Over the past decade,
the Illinois Numerical Relativity (ILNR) Group's dynamical spacetime GRMHD code
has proven itself as a robust and reliable tool for theoretical modeling of
such GRMHD phenomena. However, the code was written "by experts and for
experts" of the code, with a steep learning curve that would severely hinder
community adoption if it were open-sourced. Here we present IllinoisGRMHD,
which is an open-source, highly-extensible rewrite of the original
closed-source GRMHD code of the ILNR Group. Reducing the learning curve was the
primary focus of this rewrite, with the goal of facilitating community
involvement in the code's use and development, as well as the minimization of
human effort in generating new science. IllinoisGRMHD also saves computer time,
generating roundoff-precision identical output to the original code on
adaptive-mesh grids, but nearly twice as fast at scales of hundreds to
thousands of cores.Comment: 37 pages, 6 figures, single column. Matches published versio
Interpreting a Tatanua Mask
This article introduces the art historical method of functional deixis into the study of material culture in anthropology. Functional deixis begins with a thorough empirical description of communicative effects—visual and embodied—produced by a material thing on the beholder. It then proceeds by tending to a kind of formalisation that enables us, on the one hand, to sharpen our intuitive reaction to the thing and, on the other, to obtain detailed knowledge about the ways material things produce significance. Here, the method is applied to a tatanua mask originating from present-day Papua New Guinea and currently housed at the Grassi Museum für Völkerkunde in Leipzig, Germany. Based on a thick description, we propose an in-depth interpretation of the mask as a complex response to a fundamental injury, articulating a symbolic expression of grief (left side) with an iconic expression overcoming grief (right side) after a passage through a real word expressed through the front of the mask. In doing so, the article offers a tool to study with rather than a text to read off
R-process Nucleosynthesis from Three-Dimensional Magnetorotational Core-Collapse Supernovae
We investigate r-process nucleosynthesis in three-dimensional (3D)
general-relativistic magnetohydrodynamic simulations of rapidly rotating
strongly magnetized core collapse. The simulations include a microphysical
finite-temperature equation of state and a leakage scheme that captures the
overall energetics and lepton number exchange due to postbounce neutrino
emission and absorption. We track the composition of the ejected material using
the nuclear reaction network SkyNet. Our results show that the 3D dynamics of
magnetorotational core-collapse supernovae (CCSN) are important for their
nucleosynthetic signature. We find that production of r-process material beyond
the second peak is reduced by a factor of 100 when the magnetorotational jets
produced by the rapidly rotating core undergo a kink instability. Our results
indicate that 3D magnetorotationally powered CCSNe are a robust r-process
source only if they are obtained by the collapse of cores with unrealistically
large precollapse magnetic fields of order G. Additionally, a
comparison simulation that we restrict to axisymmetry, results in overly
optimistic r-process production for lower magnetic field strengths.Comment: 10 pages, 9 figures, 2 tables. submitted to Ap
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