277 research outputs found
Expressions 1993-1994
https://openspace.dmacc.edu/expressions/1015/thumbnail.jp
The deuteron: structure and form factors
A brief review of the history of the discovery of the deuteron in provided.
The current status of both experiment and theory for the elastic electron
scattering is then presented.Comment: 80 pages, 33 figures, submited to Advances in Nuclear Physic
TOI-2015b: A Warm Neptune with Transit Timing Variations Orbiting an Active mid M Dwarf
We report the discovery of a close-in () warm Neptune with clear transit timing variations (TTVs)
orbiting the nearby () active M4 star, TOI-2015. We
characterize the planet's properties using TESS photometry, precise
near-infrared radial velocities (RV) with the Habitable-zone Planet Finder (HP)
Spectrograph, ground-based photometry, and high-contrast imaging. A joint
photometry and RV fit yields a radius , mass , and
density for TOI-2015b,
suggesting a likely volatile-rich planet. The young, active host star has a
rotation period of and
associated rotation-based age estimate of . Though
no other transiting planets are seen in the TESS data, the system shows clear
TTVs of super period and
amplitude . After considering multiple likely
period ratio models, we show an outer planet candidate near a 2:1 resonance can
explain the observed TTVs while offering a dynamically stable solution.
However, other possible two-planet solutions -- including 3:2 and 4:3 resonance
-- cannot be conclusively excluded without further observations. Assuming a 2:1
resonance in the joint TTV-RV modeling suggests a mass of
for TOI-2015b and
for the outer candidate.
Additional transit and RV observations will be beneficial to explicitly
identify the resonance and further characterize the properties of the system.Comment: 28 pages, 15 figures, 6 tables. As submitted to AAS Journal
TOI-3984 A b and TOI-5293 A b: two temperate gas giants transiting mid-M dwarfs in wide binary systems
We confirm the planetary nature of two gas giants discovered by TESS to
transit M dwarfs with stellar companions at wide separations. TOI-3984 A
() is an M4 dwarf hosting a short-period (
days) gas giant ( and
) with a wide separation white dwarf companion.
TOI-5293 A () is an M3 dwarf hosting a short-period ( days) gas giant ( and
) with a wide separation M dwarf companion. We
characterize both systems using a combination of ground-based and space-based
photometry, speckle imaging, and high-precision radial velocities from the
Habitable-zone Planet Finder and NEID spectrographs. TOI-3984 A b
( K and ) and TOI-5293 A b
( K and ) are two of the coolest
gas giants among the population of hot Jupiter-sized gas planets orbiting M
dwarfs and are favorable targets for atmospheric characterization of temperate
gas giants and three-dimensional obliquity measurements to probe system
architecture and migration scenarios.Comment: Submitted to AJ, 42 pages, 14 figures. arXiv admin note: substantial
text overlap with arXiv:2201.0996
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Microfoundations
This paper argues that the microfoundations programme can be understood as an implementation of an underlying methodological principle—methodological individualism—and that it therefore shares a fundamental ambiguity with that principle, viz, whether the macro must be derived from and therefore reducible to, or rather consistent with, micro-level behaviours. The pluralist conclusion of the paper is not that research guided by the principle of microfoundations is necessarily wrong, but that the exclusion of approaches not guided by that principle is indeed necessarily wrong. The argument is made via an examination of the advantages claimed for dynamic stochastic general equilibrium models, the relationship between parts and wholes in social science, and the concepts of reduction, substrate neutrality, the intentional stance, and hypostatisation
Recommended from our members
Microfoundations
The paper argues that the microfoundations programme can be understood as an implementation of an underlying methodological principle, methodological individualism, and that it therefore shares a fundamental ambiguity with that principle, viz, whether the macro must be derived from and therefore reducible to, or rather consistent with micro-level behaviours. The pluralist conclusion of the paper is not that research guided by the principle of microfoundations is necessarily wrong, but that the exclusion of approaches not guided by that principle is indeed necessarily wrong. The argument is made via an examination of the advantages claimed for dynamic stochastic general equilibrium models, the relationship between parts and wholes in social science, and the concepts of reduction, substrate neutrality, the intentional stance, and hypostatisation
The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe
The preponderance of matter over antimatter in the early Universe, the
dynamics of the supernova bursts that produced the heavy elements necessary for
life and whether protons eventually decay --- these mysteries at the forefront
of particle physics and astrophysics are key to understanding the early
evolution of our Universe, its current state and its eventual fate. The
Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed
plan for a world-class experiment dedicated to addressing these questions. LBNE
is conceived around three central components: (1) a new, high-intensity
neutrino source generated from a megawatt-class proton accelerator at Fermi
National Accelerator Laboratory, (2) a near neutrino detector just downstream
of the source, and (3) a massive liquid argon time-projection chamber deployed
as a far detector deep underground at the Sanford Underground Research
Facility. This facility, located at the site of the former Homestake Mine in
Lead, South Dakota, is approximately 1,300 km from the neutrino source at
Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino
charge-parity symmetry violation and mass ordering effects. This ambitious yet
cost-effective design incorporates scalability and flexibility and can
accommodate a variety of upgrades and contributions. With its exceptional
combination of experimental configuration, technical capabilities, and
potential for transformative discoveries, LBNE promises to be a vital facility
for the field of particle physics worldwide, providing physicists from around
the globe with opportunities to collaborate in a twenty to thirty year program
of exciting science. In this document we provide a comprehensive overview of
LBNE's scientific objectives, its place in the landscape of neutrino physics
worldwide, the technologies it will incorporate and the capabilities it will
possess.Comment: Major update of previous version. This is the reference document for
LBNE science program and current status. Chapters 1, 3, and 9 provide a
comprehensive overview of LBNE's scientific objectives, its place in the
landscape of neutrino physics worldwide, the technologies it will incorporate
and the capabilities it will possess. 288 pages, 116 figure
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