13,260 research outputs found
Confinement in Three Dimensions and the Electroweak Phase Transition
The infrared behaviour of the standard model at finite temperature is
determined by the confining phase of the SU(2)-Higgs model in three dimensions.
Due to the Landau singularity of the three-dimensional gauge theory the
perturbative treatment of the electroweak phase transition breaks down for
Higgs masses above a critical mass . Based on a renormalization group
improved effective potential we find 70 GeV. The scalar
self-coupling has a Landau-type singularity also in the abelian U(1)-Higgs
model, which leads to a breakdown of perturbation theory in the symmetric
phase.Comment: 9 pages, DESY-94-045, 4 figures can be obtained via e-mail from
[email protected]
STS-31 Space Shuttle mission report
The STS-31 Space Shuttle Program Mission Report contains a summary of the vehicle subsystem activities on this thirty-fifth flight of the Space Shuttle and the tenth flight of the Orbiter Vehicle Discovery (OV-103). In addition to the Discovery vehicle, the flight vehicle consisted of an External Tank (ET) (designated as ET-34/LWT-27), three Space Shuttle main engines (SSME's) (serial numbers 2011, 2031, and 2107), and two Solid Rocket Booster (SRB) (designated as BI-037). The primary objective of the mission was to place the Hubble Space Telescope (HST) into a 330 nmi. circular orbit having an inclination of 28.45 degrees. The secondary objectives were to perform all operations necessary to support the requirements of the Protein Crystal Growth (PCG), Investigations into Polymer Membrane Processing (IPMP), Radiation Monitoring Equipment (RME), Ascent Particle Monitor (APM), IMAX Cargo Bay Camera (ICBC), Air Force Maui Optical Site Calibration Test (AMOS), IMAX Crew Compartment Camera, and Ion Arc payloads. In addition, 12 development test objectives (DTO's) and 10 detailed supplementary objectives (DSO's) were assigned to the flight. The sequence of events for this mission is shown. The significant problems that occurred in the Space Shuttle Orbiter subsystems during the mission are summarized, and the official problem tracking list is presented. In addition, each of the Space Shuttle Orbiter problems is cited in the subsystem discussion
STS-38 Space Shuttle mission report
The STS-38 Space Shuttle Program Mission Report contains a summary of the vehicle subsystem activities on this thirty-seventh flight of the Space Shuttle and the seventh flight of the Orbiter vehicle Atlantis (OV-104). In addition to the Atlantis vehicle, the flight vehicle consisted of an External Tank (ET) (designated as ET-40/LWT-33), three Space Shuttle main engines (SSME's) (serial numbers 2019, 2022, 2027), and two Solid Rocket Boosters (SRB's), designated as BI-039. The STS-38 mission was a classified Department of Defense mission, and as much, the classified portions of the mission are not presented in this report. The sequence of events for this mission is shown. The significant problems that occurred in the Space Shuttle Orbiter subsystem during the mission are summarized and the official problem tracking list is presented. In addition, each Space Shuttle Orbiter problem is cited in the subsystem discussion
STS-35 Space Shuttle mission report
The STS-35 Space Shuttle Program Mission Report contains a summary of the vehicle subsystem activities during this thirty-eighth flight of the Space Shuttle and the tenth flight of the Orbiter vehicle Columbia (OV-102). In addition to the Columbia vehicle, the flight vehicle consisted of an External Tank (ET) (designated as ET-35/LWT-28), three Space Shuttle main engines (SSME's) (serial numbers 2024, 2012, and 2028 in positions 1, 2, and 3, respectively), and two Solid Rocket Boosters (SRB's) designated as BI-038. The primary objectives of this flight were to successfully perform the planned operations of the Ultraviolet Astronomy (Astro-1) payload and the Broad-Band X-Ray Telescope (BBXRT) payload in a 190-nmi. circular orbit which had an inclination of 28.45 degrees. The sequence of events for this mission is shown in tablular form. Summarized are the significant problems that occurred in the Orbiter subsystems during the mission. The official problem tracking list is presented. In addition, each Orbiter subsystem problem is cited in the applicable subsystem discussion
STS-41 Space Shuttle mission report
The STS-41 Space Shuttle Program Mission Report contains a summary of the vehicle subsystem activities on this thirty-sixth flight of the Space Shuttle and the eleventh flight of the Orbiter vehicle, Discovery (OV-103). In addition to the Discovery vehicle, the flight vehicle consisted of an External Tank (ET) (designated as ET-39/LWT-32), three Space Shuttle main engines (SSME's) (serial numbers 2011, 2031, and 2107), and two Solid Rocket Boosters (SRB's), designated as BI-040. The primary objective of the STS-41 mission was to successfully deploy the Ulysses/inertial upper stage (IUS)/payload assist module (PAM-S) spacecraft. The secondary objectives were to perform all operations necessary to support the requirements of the Shuttle Backscatter Ultraviolet (SSBUV) Spectrometer, Solid Surface Combustion Experiment (SSCE), Space Life Sciences Training Program Chromosome and Plant Cell Division in Space (CHROMEX), Voice Command System (VCS), Physiological Systems Experiment (PSE), Radiation Monitoring Experiment - 3 (RME-3), Investigations into Polymer Membrane Processing (IPMP), Air Force Maui Optical Calibration Test (AMOS), and Intelsat Solar Array Coupon (ISAC) payloads. The sequence of events for this mission is shown in tabular form. Summarized are the significant problems that occurred in the Orbiter subsystems during the mission. The official problem tracking list is presented. In addition, each Orbiter problem is cited in the subsystem discussion
New N=1 Extended Superconformal Algebras with Two and Three Generators
In this paper we consider extensions of the super Virasoro algebra by one and
two super primary fields. Using a non-explicitly covariant approach we compute
all SW-algebras with one generator of dimension up to 7 in addition to the
super Virasoro field. In complete analogy to W-algebras with two generators
most results can be classified using the representation theory of the super
Virasoro algebra. Furthermore, we find that the SW(3/2, 11/2)-algebra can be
realized as a subalgebra of SW(3/2, 5/2) at c = 10/7. We also construct some
new SW-algebras with three generators, namely SW(3/2, 3/2, 5/2), SW(3/2, 2, 2)
and SW(3/2, 2, 5/2).Comment: 30 pages (Plain TeX), BONN-HE-92-0
Three-dimensional simulations of type Ia supernovae
We present the results of three-dimensional hydrodynamical simulations of the
subsonic thermonuclear burning phase in type Ia supernovae. The burning front
model contains no adjustable parameters so that variations of the explosion
outcome can be linked directly to changes in the initial conditions. In
particular, we investigate the influence of the initial flame geometry on the
explosion energy and find that it appears to be weaker than in 2D. Most
importantly, our models predict global properties such as the produced nickel
masses and ejecta velocities within their observed ranges without any fine
tuning.Comment: 7 pages, 5 figures, accepted by A&
An Atlas of Spectrophotometric Landolt Standard Stars
We present CCD observations of 102 Landolt standard stars obtained with the
R-C spectrograph on the CTIO 1.5 m telescope. Using stellar atmosphere models
we have extended the flux points to our six spectrophotometric secondary
standards, in both the blue and the red, allowing us to produce flux-calibrated
spectra that span a wavelength range from 3050 \AA to 1.1 \micron. Mean
differences between UBVRI spectrophotometry computed using Bessell's standard
passbands and Landolt's published photometry is found to be 1% or less.
Observers in both hemispheres will find these spectra useful for
flux-calibrating spectra and through the use of accurately constructed
instrumental passbands be able to compute accurate corrections to bring
instrumental magnitudes to any desired standard photometric system
(S-corrections). In addition, by combining empirical and modeled spectra of the
Sun, Sirius and Vega, we calculate and compare synthetic photometry to observed
photometry taken from the literature for these three stars.Comment: Added referee's comments, minor corrections, replaced Table 1
SN1997cy/GRB970514 - A New Piece in the GRB Puzzle?
We present observations of SN1997cy, a supernova discovered as part of the
Mount Stromlo Abell Cluster SN Search, which does not easily fit into the
traditional classification scheme for supernovae. This object's extraordinary
optical properties and coincidence with GRB970514, a short duration gamma ray
burst, suggest a second case, after SN1998bw/GRB980425, for a SN-GRB
association. SN1997cy is among the most luminous SNe yet discovered and has a
peculiar spectrum. We present evidence that SN1997cy ejected approximately 2
solar masses of 56Ni, supported by its late-time light curve, and FeII/[FeIII]
lines in its spectrum, although it is possible that both these observations can
be explained via circumstellar interaction. While SN1998bw and SN1997cy appear
to be very different objects with respect to both their gamma ray and optical
properties, SN1997cy and the optical transient associated with GRB970508 have
roughly similar late-time optical behavior. This similarity may indicate that
the late-time optical output of these two intrinsically bright transient events
have a common physical process. Although the connection between GRB970514 and
SN1997cy is suggestive, it is not conclusive. However, if this association is
real, followup of short duration GRBs detected with BATSE or HETE2 should
reveal objects similar to SN1997cy.Comment: 26 pages including 6 postscript figures and 3 tables. Submitted to
ApJ. Re-calibrated photometry - objects are about 0.3mags brighter than in
original versio
The Mount Stromlo Abell Cluster Supernova Search
We have initiated a three-year project to find supernovae (SNe) in a
well-defined sample of high-density southern Abell clusters with redshifts
. These observations will provide a volume-limited sample of SNe Ia
to more than a magnitude below their peak brightness, and will enable us to:
(1) measure the luminosity function of SNe, (2) further explore the correlation
of light curve shape with the absolute luminosity of SNe Ia to better
understand SNe Ia as distance indicators, (3) measure SN rates, (4) measure the
bulk motion of the Local Group using SNe Ia, and (5) directly compare SN Ia
distances to brightest cluster galaxy distances. We use the MaCHO wide-field
2-color imager on the 1.3m telescope at Mount Stromlo to routinely monitor
clusters per week. We describe our technique for target selection and
scheduling search observations, and for finding and identifying SN candidates.
We also describe the results from the first year of our program, including the
detection of 19 SNe, several RR-Lyrae variables, and hundreds of asteroids.Comment: 20 pages, 10 figures, 3 tables. Accepted for publication in AJ, Jan.
1998 issu
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