139 research outputs found
Color-Octet Production in the Decay
The direct production rate of in the decay is shown to be
dominated by the process followed by via
the color-octet mechanism proposed recently to explain the anomalous prompt
charmonium production at the Tevatron. We show that this plausibly dominant
process has a branching ratio compatible with the experimental data. Further
experimental study in this channel is important to test the significance of the
color-octet component of pair inside the system.Comment: 20 pages, Standard LaTeX, 2 figures; a couple of new processes added,
but conclusion unchange
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The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope: I. Overview of the instrument and its capabilities
We provide an overview of the design and capabilities of the near-infrared
spectrograph (NIRSpec) onboard the James Webb Space Telescope. NIRSpec is
designed to be capable of carrying out low-resolution () prism
spectroscopy over the wavelength range m and higher resolution
( or ) grating spectroscopy over
m, both in single-object mode employing any one of five fixed
slits, or a 3.13.2 arcsec integral field unit, or in multiobject
mode employing a novel programmable micro-shutter device covering a
3.63.4~arcmin field of view. The all-reflective optical chain of
NIRSpec and the performance of its different components are described, and some
of the trade-offs made in designing the instrument are touched upon. The
faint-end spectrophotometric sensitivity expected of NIRSpec, as well as its
dependency on the energetic particle environment that its two detector arrays
are likely to be subjected to in orbit are also discussed
The Near-Infrared Spectrograph (NIRSpec) on the James Webb Space Telescope: I. Overview of the instrument and its capabilities
We provide an overview of the design and capabilities of the near-infrared
spectrograph (NIRSpec) onboard the James Webb Space Telescope. NIRSpec is
designed to be capable of carrying out low-resolution () prism
spectroscopy over the wavelength range m and higher resolution
( or ) grating spectroscopy over
m, both in single-object mode employing any one of five fixed
slits, or a 3.13.2 arcsec integral field unit, or in multiobject
mode employing a novel programmable micro-shutter device covering a
3.63.4~arcmin field of view. The all-reflective optical chain of
NIRSpec and the performance of its different components are described, and some
of the trade-offs made in designing the instrument are touched upon. The
faint-end spectrophotometric sensitivity expected of NIRSpec, as well as its
dependency on the energetic particle environment that its two detector arrays
are likely to be subjected to in orbit are also discussed
Search For Exotic Tau-decays
The Crystal Ball detector at the Doris II storage ring at DESY was used to search for the exotic decay processes tau -> e gamma, tau -> e pi0, tau -> e eta. No signal was observed. We obtained the following 90% CL upper limits on the branching fractions:B(tau -> e gamma)< 2.0x10^(-4),B(tau -> e pi0) < 1.4x10^(-4),B(tau -> e eta) < 2.4x10^(-4)
The Science Performance of JWST as Characterized in Commissioning
This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies
The James Webb Space Telescope Mission
Twenty-six years ago a small committee report, building on earlier studies,
expounded a compelling and poetic vision for the future of astronomy, calling
for an infrared-optimized space telescope with an aperture of at least .
With the support of their governments in the US, Europe, and Canada, 20,000
people realized that vision as the James Webb Space Telescope. A
generation of astronomers will celebrate their accomplishments for the life of
the mission, potentially as long as 20 years, and beyond. This report and the
scientific discoveries that follow are extended thank-you notes to the 20,000
team members. The telescope is working perfectly, with much better image
quality than expected. In this and accompanying papers, we give a brief
history, describe the observatory, outline its objectives and current observing
program, and discuss the inventions and people who made it possible. We cite
detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space
Telescope Overview, 29 pages, 4 figure
The Science Performance of JWST as Characterized in Commissioning
This paper characterizes the actual science performance of the James Webb
Space Telescope (JWST), as determined from the six month commissioning period.
We summarize the performance of the spacecraft, telescope, science instruments,
and ground system, with an emphasis on differences from pre-launch
expectations. Commissioning has made clear that JWST is fully capable of
achieving the discoveries for which it was built. Moreover, almost across the
board, the science performance of JWST is better than expected; in most cases,
JWST will go deeper faster than expected. The telescope and instrument suite
have demonstrated the sensitivity, stability, image quality, and spectral range
that are necessary to transform our understanding of the cosmos through
observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures;
https://iopscience.iop.org/article/10.1088/1538-3873/acb29
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