1,508 research outputs found
Van der Waals bond lengths and electronic spectral shifts of the benzene---Kr and benzene---Xe complexes
Rotationally resolved UV-spectra are presented for the 610 bands of benzene---Kr and benzene---Xe complexes yielding precise rotational constants and van der Waals bond lengths for the ground and excited vibronic state, and electronic band shifts. These value complement the previously published data for the other rare gases and the various quantities have now been determined for all the benzene—rare gas complexes. Measured values of the bond length were used to calculate the band shifts from recent theoretical predictions. They are compared with the experimental values of this work
Jet-ISM interactions near the microquasars GRS 1758-258 and 1E 1740.7-2942
We present Atacama Large Millimeter/Sub-millimeter Array observations of the candidate jet-ISM interaction zones near the black hole X-ray binaries GRS 1758-258 and 1E 1740.7-2942. Using these data, we map the molecular line emission in the regions, detecting emission from the HCN [J = 1-0], HCO+ [J = 1-0], SiO [J = 2-1], CS [J = 2-1], 13CO [J = 1-0], C18O [J = 1-0], HNCO [J = 40,4-30,3], HNCO [J = 50,5-40,4], and CH3OH [J = 21,1-11,0] molecular transitions. Through examining the morphological, spectral, and kinematic properties of this emission, we identify molecular structures that may trace jet-driven cavities in the gas surrounding these systems. Our results from the GRS 1758-258 region in particular, are consistent with recent work, which postulated the presence of a jet-blown cocoon structure in deep radio continuum maps of the region. Using these newly discovered molecular structures as calorimeters, we estimate the time averaged jet power from these systems, finding (1.1-5.7) × 1036 erg s-1 over 0.12-0.31 Myr for GRS 1758-258 and (0.7-3.5) × 1037 erg s-1 over 0.10-0.26 Myr for 1E 1740.7-2942. Additionally, the spectral line characteristics of the detected emission place these molecular structures in the central molecular zone of our Galaxy, thereby constraining the distances to the black hole X-ray binaries to be 8.0 ± 1.0 kpc. Overall, our analysis solidifies the diagnostic capacity of molecular lines, and highlights how astro-chemistry can both identify jet-ISM interaction zones and probe jet feedback from Galactic X-ray binaries
Detecting a stochastic background of gravitational radiation: Signal processing strategies and sensitivities
We analyze the signal processing required for the optimal detection of a
stochastic background of gravitational radiation using laser interferometric
detectors. Starting with basic assumptions about the statistical properties of
a stochastic gravity-wave background, we derive expressions for the optimal
filter function and signal-to-noise ratio for the cross-correlation of the
outputs of two gravity-wave detectors. Sensitivity levels required for
detection are then calculated. Issues related to: (i) calculating the
signal-to-noise ratio for arbitrarily large stochastic backgrounds, (ii)
performing the data analysis in the presence of nonstationary detector noise,
(iii) combining data from multiple detector pairs to increase the sensitivity
of a stochastic background search, (iv) correlating the outputs of 4 or more
detectors, and (v) allowing for the possibility of correlated noise in the
outputs of two detectors are discussed. We briefly describe a computer
simulation which mimics the generation and detection of a simulated stochastic
gravity-wave signal in the presence of simulated detector noise. Numerous
graphs and tables of numerical data for the five major interferometers
(LIGO-WA, LIGO-LA, VIRGO, GEO-600, and TAMA-300) are also given. The treatment
given in this paper should be accessible to both theorists involved in data
analysis and experimentalists involved in detector design and data acquisition.Comment: 81 pages, 30 postscript figures, REVTE
Irreducible triangulations of surfaces with boundary
A triangulation of a surface is irreducible if no edge can be contracted to
produce a triangulation of the same surface. In this paper, we investigate
irreducible triangulations of surfaces with boundary. We prove that the number
of vertices of an irreducible triangulation of a (possibly non-orientable)
surface of genus g>=0 with b>=0 boundaries is O(g+b). So far, the result was
known only for surfaces without boundary (b=0). While our technique yields a
worse constant in the O(.) notation, the present proof is elementary, and
simpler than the previous ones in the case of surfaces without boundary
Spinless particle in rapidly fluctuating random magnetic field
We study a two-dimensional spinless particle in a disordered gaussian
magnetic field with short time fluctuations, by means of the evolution equation
for the density matrix ; in this
description the two coordinates are associated with the retarded and advanced
paths respectively. The static part of the vector potential correlator is
assumed to grow with distance with a power ; the case corresponds to
a -correlated magnetic field, and to free massless field. The
value separates two different regimes, diffusion and logarithmic growth
respectively. When the baricentric coordinate diffuses with a coefficient proportional to , where
is the relative coordinate: . As the
correlator of the magnetic field is a power of distance with positive exponent;
then the coefficient scales as .
The density matrix is a function of and ,and its width in
grows for large times proportionally to .Comment: latex2e; 2 figure
Determining the Higgs Boson Self Coupling at Hadron Colliders
Inclusive Standard Model Higgs boson pair production at hadron colliders has
the capability to determine the Higgs boson self-coupling, lambda. We present a
detailed analysis of the gg\to HH\to (W^+W^-)(W^+W^-)\to
(jjl^\pm\nu)(jj{l'}^\pm\nu) and gg\to HH\to (W^+W^-)(W^+W^-)\to
(jjl^\pm\nu)({l'}^\pm\nu {l''}^\mp\nu) (l, {l'}, {l''}=e, \mu) signal channels,
and the relevant background processes, for the CERN Large Hadron Collider, and
a future Very Large Hadron Collider operating at a center-of-mass energy of 200
TeV. We also derive quantitative sensitivity limits for lambda. We find that it
should be possible at the LHC with design luminosity to establish that the
Standard Model Higgs boson has a non-zero self-coupling and that lambda /
lambda_{SM} can be restricted to a range of 0-3.8 at 95% confidence level (CL)
if its mass is between 150 and 200 GeV. At a 200 TeV collider with an
integrated luminosity of 300 fb^{-1}, lambda can be determined with an accuracy
of 8 - 25% at 95% CL in the same mass range.Comment: 28 pages, Revtex3, 9 figures, 3 table
Effects of Impurity Content on the Sintering Characteristics of Plasma-Sprayed Zirconia
Yttria-stabilized zirconia powders, containing different levels of SiO2 and Al2O3, have been plasma sprayed onto metallic substrates. The coatings were detached from their substrates and a dilatometer was used to monitor the dimensional changes they exhibited during prolonged heat treatments. It was found that specimens containing higher levels of silica and alumina exhibited higher rates of linear contraction, in both in-plane and through-thickness directions. The in-plane stiffness and the through-thickness thermal conductivity were also measured after different heat treatments and these were found to increase at a greater rate for specimens with higher impurity (silica and alumina) levels. Changes in the pore architecture during heat treatments were studied using Mercury Intrusion Porosimetry (MIP). Fine scale porosity (<_50 nm) was found to be sharply reduced even by relatively short heat treatments. This is correlated with improvements in inter-splat bonding and partial healing of intra-splat microcracks, which are responsible for the observed changes in stiffness and conductivity, as well as the dimensional changes
A New Relativistic High Temperature Bose-Einstein Condensation
We discuss the properties of an ideal relativistic gas of events possessing
Bose-Einstein statistics. We find that the mass spectrum of such a system is
bounded by where is the usual chemical
potential, is an intrinsic dimensional scale parameter for the motion of an
event in space-time, and is an additional mass potential of the
ensemble. For the system including both particles and antiparticles, with
nonzero chemical potential the mass spectrum is shown to be bounded by
and a special type of high-temperature
Bose-Einstein condensation can occur. We study this Bose-Einstein condensation,
and show that it corresponds to a phase transition from the sector of
continuous relativistic mass distributions to a sector in which the boson mass
distribution becomes sharp at a definite mass This phenomenon
provides a mechanism for the mass distribution of the particles to be sharp at
some definite value.Comment: Latex, 22 page
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