49,337 research outputs found
Inverter ratio failure detector
A failure detector which detects the failure of a dc to ac inverter is disclosed. The inverter under failureless conditions is characterized by a known linear relationship of its input and output voltages and by a known linear relationship of its input and output currents. The detector includes circuitry which is responsive to the detector's input and output voltages and which provides a failure-indicating signal only when the monitored output voltage is less by a selected factor, than the expected output voltage for the monitored input voltage, based on the known voltages' relationship. Similarly, the detector includes circuitry which is responsive to the input and output currents and provides a failure-indicating signal only when the input current exceeds by a selected factor the expected input current for the monitored output current based on the known currents' relationship
Higgs-Stoponium Mixing Near the Stop-Antistop Threshold
Supersymmetric extensions of the standard model contain additional heavy
neutral Higgs bosons that are coupled to heavy scalar top quarks (stops). This
system exhibits interesting field theoretic phenomena when the Higgs mass is
close to the stop-antistop production threshold. Existing work in the
literature has examined the digluon-to-diphoton cross section near threshold
and has focused on enhancements in the cross section that might arise either
from the perturbative contributions to the Higgs-to-digluon and
Higgs-to-diphoton form factors or from mixing of the Higgs boson with stoponium
states. Near threshold, enhancements in the relevant amplitudes that go as
inverse powers of the stop-antistop relative velocity require resummations of
perturbation theory and/or nonperturbative treatments. We present a complete
formulation of threshold effects at leading order in the stop-antistop relative
velocity in terms of nonrelativistic effective field theory. We give detailed
numerical calculations for the case in which the stop-antistop Green's function
is modeled with a Coulomb-Schr\"odinger Green's function. We find several
general effects that do not appear in a purely perturbative treatment.
Higgs-stop-antistop mixing effects displace physical masses from the threshold
region, thereby rendering the perturbative threshold enhancements inoperative.
In the case of large Higgs-stop-antistop couplings, the displacement of a
physical state above threshold substantially increases its width, owing to its
decay width to a stop-antistop pair, and greatly reduces its contribution to
the cross section.Comment: 45 pages, 13 figures, minor corrections, references added, figures
2--5 updated, version published in Phys. Rev.
Minimal Flavor Violation and the Scale of Supersymmetry Breaking
In this paper we explore the constraints from B-physics observables in SUSY
models of Minimal Flavor Violation, in the large tan beta regime, for both low
and high scale supersymmetry breaking scenarios. We find that the rare B-decays
b -> s gamma and B_s -> mu+ mu- can be quite sensitive to the scale M at which
supersymmetry breaking is communicated to the visible sector. In the case of
high scale supersymmetry breaking, we show that the additional gluino
contribution to the b -> s gamma and B_s -> mu+ mu- rare decay rates can be
significant for large tan beta, mu and M_3. The constraints on B_u -> tau nu
are relatively insensitive to the precise scale of M. We also consider the
additional constraints from the present direct Higgs searches at the Tevatron
in the inclusive H/A -> tau tau channel, and the latest CDMS direct dark matter
detection experiments. We find that altogether the constraints from B-physics,
Higgs physics and direct dark matter searches can be extremely powerful in
probing regions of SUSY parameter space for low M_A and large tan beta, leading
to a preference for models with a lightest CP-even Higgs mass close to the
current experimental limit. We find interesting regions of parameter space that
satisfy all constraints and can be probed by Higgs searches at the Tevatron and
the LHC and by direct dark matter searches in the near future.Comment: 24 pages, 6 figures. Added citations. Published in PR
Low-momentum Hyperon-Nucleon Interactions
We present a first exploratory study for hyperon-nucleon interactions using
renormalization group techniques. The effective two-body low-momentum potential
V_low-k is obtained by integrating out the high-momentum components from
realistic Nijmegen YN potentials. A T-matrix equivalence approach is employed,
so that the low-energy phase shifts are reproduced by V_low-k up to a momentum
scale Lambda ~ 500 MeV. Although the various bare Nijmegen models differ
somewhat from each other, the corresponding V_low-k interactions show
convergence in some channels, suggesting a possible unique YN interaction at
low momenta.Comment: 4 pages, 6 figure
High spatial resolution measurements of NO<sub>2</sub> applying Topographic Target Light scattering-Differential Optical Absorption Spectroscopy (ToTaL-DOAS)
International audienceTomographic Target Light scattering ? Differential Optical Absorption Spectroscopy (ToTaL-DOAS), also called Target-DOAS, is a novel experimental procedure to retrieve trace gas concentrations present in the low atmosphere. Scattered sunlight (partially or totally) reflected from natural or artificial targets of similar albedo located at different distances is analyzed to retrieve the concentration of different trace gases like NO2, SO2 and others. We report high spatial resolution measurements of NO2 mixing ratios in the city of Montevideo (Uruguay) observing three buildings as targets with a Mini-DOAS instrument. Our instrument was 146 m apart from the first building, 196 m from the second and 286 m from the third one. All three buildings are located along a main Avenue. We obtain temporal variation of NO2 mixing ratios between 30 ppb and 65 ppb (±2 ppb). Our measurements demonstrate that ToTaL-DOAS measurements can be made over very short distances. In polluted air masses, the retrieved absorption signal was found to be strong enough to allow measurements over distances in the range of several ten meters, and achieve a spatial resolution of 50 m approximately
Progress of the Felsenkeller shallow-underground accelerator for nuclear astrophysics
Low-background experiments with stable ion beams are an important tool for
putting the model of stellar hydrogen, helium, and carbon burning on a solid
experimental foundation. The pioneering work in this regard has been done by
the LUNA collaboration at Gran Sasso, using a 0.4 MV accelerator. In the
present contribution, the status of the project for a higher-energy underground
accelerator is reviewed. Two tunnels of the Felsenkeller underground site in
Dresden, Germany, are currently being refurbished for the installation of a 5
MV high-current Pelletron accelerator. Construction work is on schedule and
expected to complete in August 2017. The accelerator will provide intense, 50
uA, beams of 1H+, 4He+, and 12C+ ions, enabling research on astrophysically
relevant nuclear reactions with unprecedented sensitivity.Comment: Submitted to the Proceedings of Nuclei in the Cosmos XIV, 19-24 June
2016, Niigata/Japa
- …