15,008 research outputs found
The thermal noise of cascaded mismatched passive two-ports in the microwave range
Thermal noise calculation of cascaded mismatched passive two-ports in microwave rang
Reduction of noise in gyro outputs
Technique is described to reduce extraneous gyro output signals by using relatively inexpensive shrouds which do not increase power comsumption. Shrouds reduce noise by minimizing mass of gas spinning with rotor, reducing Reynolds number near rotor, and inducing laminar flow
Hawking Radiation as Tunneling
We present a short and direct derivation of Hawking radiation as a tunneling
process, based on particles in a dynamical geometry. The imaginary part of the
action for the classically forbidden process is related to the Boltzmann factor
for emission at the Hawking temperature. Because the derivation respects
conservation laws, the exact spectrum is not precisely thermal. We compare and
contrast the problem of spontaneous emission of charged particles from a
charged conductor.Comment: LaTeX, 10 pages; v2. journal version, added section on relation of
black hole radiation to electric charge emission from a charged conducting
sphere; v3. restored cut referenc
Disk tracing for B[e] supergiants in the Magellanic Clouds
B[e] supergiants are evolved massive stars with a complex circumstellar
environment. A number of important emission features probe the structure and
the kinematics of the circumstellar material. In our survey of Magellanic Cloud
B[e] supergiants we focus on the [OI] and [CaII] emission lines, which we
identified in four more objects.Comment: 2 pages; 1 figure; submitted to the proceedings of the Physics of
Evolved Stars - A conference dedicated to the memory of Olivier Chesneau,
Nice, France, June 8-12, 201
Large Area Crop Inventory Experiment (LACIE). Evaluation of multitemporal data enchancements for the identification of winter wheat fields
There are no author-identified significant results in this report
Off-shell Top Quarks with One Jet at the LHC: A comprehensive analysis at NLO QCD
We present a comprehensive study of the production of top quark pairs in
association with one hard jet in the di-lepton decay channel at the LHC. Our
predictions, accurate at NLO in QCD, focus on the LHC Run II with a
center-of-mass energy of 13 TeV. All resonant and non-resonant contributions at
the perturbative order are taken into account,
including irreducible backgrounds to production, interferences and
off-shell effects of the top quark and the gauge boson. We extensively
investigate the dependence of our results upon variation of renormalisation and
factorisation scales and parton distribution functions in the quest for an
accurate estimate of the theoretical uncertainties. Additionally, we explore a
few possibilities for a dynamical scale choice with the goal of stabilizing the
perturbative convergence of the differential cross sections far away from the
threshold. Results presented here are particularly relevant for
searches of new physics as well as for precise measurements of the top-quark
fiducial cross sections and top-quark properties at the LHC.Comment: 51 pages, 36 figures, 6 tables, version to appear in JHE
Rigid invariance as derived from BRS invariance: The abelian Higgs model
Consequences of a symmetry, e.g.\ relations amongst Green functions, are
renormalization scheme independently expressed in terms of a rigid Ward
identity. The corresponding local version yields information on the respective
current. In the case of spontaneous breakdown one has to define the theory via
the BRS invariance and thus to construct rigid and current Ward identity
non-trivially in accordance with it. We performed this construction to all
orders of perturbation theory in the abelian Higgs model as a prelude to the
standard model. A technical tool of interest in itself is the use of a doublet
of external scalar ``background'' fields. The Callan-Symanzik equation has an
interesting form and follows easily once the rigid invariance is established.Comment: 33 pages, Plain Te
Chiral black hole in three-dimensional gravitational Chern-Simons
A chiral black hole can be defined from the three-dimensional pure
gravitational Chern-Simons action as an independent gravitational theory. The
third order derivative of the Cotton tensor gives a dimensional constant which
plays a role of the cosmological constant. The handedness of angular momentum
depends on the signature of the Chern-Simons coefficient. Even in the massless
black hole which corresponds to the static black hole, it has a nonvanishing
angular momentum. We also study statistical entropy and thermodynamic
stability.Comment: 6 pages, a reference added, minor changes to introductio
The High-Order-Multiplicity of Unusually Wide M-dwarf Binaries: Eleven New Triple and Quadruple Systems
M-dwarfs in extremely wide binary systems are very rare, and may thus have
different formation processes from those found as single stars or close
binaries in the field. In this paper we search for close companions to a new
sample of 36 extremely wide M-dwarf binaries, covering a spectral type range of
M1 to M5 and a separation range of 600 - 6500 AU. We discover 10 new triple
systems and one new quadruple system. We carefully account for selection
effects including proper motion, magnitude limits, the detection of close
binaries in the SDSS, and other sample biases. The bias-corrected total
high-order-multiple fraction is 45% (+18%/-16%) and the bias-corrected
incidence of quadruple systems is < 5%, both statistically compatible with that
found for the more common close M-dwarf multiple systems. Almost all the
detected companions have similar masses to their primaries, although two very
low mass companions, including a candidate brown dwarf, are found at relatively
large separations. We find that the close-binary separation distribution is
strongly peaked towards < 30AU separations. There is marginally significant
evidence for a change in high-order M-dwarf multiplicity with binding energy
and total mass. We also find 2-sigma evidence of an unexpected increased
high-order-multiple fraction for the widest targets in our survey, with a
high-order-multiple fraction of 21% (+17%/-7%) for systems with separations up
to 2000AU, compared to 77% (+9%/-22%) for systems with separations > 4000AU.
These results suggest that the very widest M-dwarf binary systems need higher
masses to form or to survive.Comment: 11 pages, 14 figures, accepted for publication in Ap
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