35 research outputs found
Gravitational Wave Emission From a Binary Black Hole System in Presence of an Accretion Disk
We study time evolution and gravitational wave emission properties of a black
hole orbiting {\it inside} an accretion disk surrounding a massive black hole.
We simultaneously solve the structure equations of the accretion disk in
presence of heating, cooling and viscosity as well as the equations governing
the companion orbit. The deviation from Keplerian distribution of angular
momentum of the disk due to pressure and advection effects causes a significant
exchange of angular momentum between the disk and the companion. This
significantly affects the gravitational wave emission properties from the
binary system. We show that when the companion is light, the effect is
extremely important and must be taken into account while interpreting
gravitational wave signals from such systems.Comment: 8 pages of Latex plus postscript fil
Cascade decays of triplet Higgs bosons at LEP2
We study the Georgi-Machacek two triplet, one doublet model in the context of
LEP2, and show that cascade decays of Higgs bosons to lighter Higgs bosons and
a virtual vector boson may play a major role. Such decays would allow the Higgs
bosons of this model to escape current searches, and in particular are of great
importance for the members of the five-plet which will always decay to the
three-plet giving rise to cascade signatures.Comment: 17 pages Latex, 6 figures, some graphs changed slightly, a formula
corrected, to appear in Physics Letters
Doubly charged Higgs from - scattering in the 3-3-1 Model
We studied the production and signatures of doubly charged Higgs bosons in
the process , where is a heavy lepton,
at the International Linear Collider (ILC) and CERN Linear Collider
(CLIC). The intermediate photons are given by the Weizscker-Williams
and laser backscattering distributions. We found that significant signatures
are obtained by bremsstrahlung and backward Comptom scattering of laser. A
clear signal can be obtained for doubly charged Higgs bosons, doubly charged
gauge bosons and heavy leptons
Synthesis of Quantum Circuits for Linear Nearest Neighbor Architectures
While a couple of impressive quantum technologies have been proposed, they
have several intrinsic limitations which must be considered by circuit
designers to produce realizable circuits. Limited interaction distance between
gate qubits is one of the most common limitations. In this paper, we suggest
extensions of the existing synthesis flow aimed to realize circuits for quantum
architectures with linear nearest neighbor (LNN) interaction. To this end, a
template matching optimization, an exact synthesis approach, and two reordering
strategies are introduced. The proposed methods are combined as an integrated
synthesis flow. Experiments show that by using the suggested flow, quantum cost
can be improved by more than 50% on average.Comment: 14 pages, 11 figures, 3 table
Higgs sector and R-parity breaking couplings in models with broken U(1)_B-L gauge symmetry
Four different supersymmetric models based on SU(2)_L X U(1)_R X U(1)_B-L and
SU(2)_L X SU(2)_R X U(1)_B-L gauge symmetry groups are studied. U(1)_B-L
symmetry is broken spontaneously by a vacuum expectation value (VEV) of a
sneutrino field. The right-handed gauge bosons may obtain their mass solely by
sneutrino VEV. The physical charged lepton and neutrino are mixtures of
gauginos, higgsinos and lepton interaction eigenstates. Explicit formulae for
masses and mixings in the physical lepton fields are found. The spontaneous
symmetry breaking mechanism fixes the trilinear R-parity breaking couplings.
Only some special R-parity breaking trilinear couplings are allowed. There is a
potentially large trilinear lepton number breaking coupling - which is unique
to left-right models - that is proportional to the SU(2)_R gauge coupling g_R.
The couplings are parametrized by few mixing angles, making the spontaneous
R-parity breaking a natural ``unification framework'' for R-parity breaking
couplings in SUSYLR models.Comment: 19 pages, no figures, uses REVTeX. To be published in PR
Low-density star cluster formation: Discovery of a young faint fuzzy on the outskirts of the low-mass spiral galaxy NGC 247
The classical globular clusters found in all galaxy types have half-light radii of rh ~2-4 pc, which have been tied to formation in the dense cores of giant molecular clouds. Some old star clusters have larger sizes, and it is unclear if these represent a fundamentally different mode of low-density star cluster formation. We report the discovery of a rare, young \u27faint fuzzy\u27 star cluster, NGC 247-SC1, on the outskirts of the low-mass spiral galaxy NGC 247 in the nearby Sculptor group, and measure its radial velocity using Keck spectroscopy. We use Hubble Space Telescope imaging to measure the cluster half-light radius of rh ≃ 12 pc and a luminosity of LV ≃ 4 × 105Lθ. We produce a colour-magnitude diagram of cluster stars and compare to theoretical isochrones, finding an age of ≃300 Myr, a metallicity of [Z/H] ~-0.6 and an inferred mass of M∗ ≃ 9 × 104Mθ. The narrow width of blue-loop star magnitudes implies an age spread of ≲50 Myr, while no old red-giant branch stars are found, so SC1 is consistent with hosting a single stellar population, modulo several unexplained bright \u27red straggler\u27 stars. SC1 appears to be surrounded by tidal debris, at the end of an ∼2 kpc long stellar filament that also hosts two low-mass, low-density clusters of a similar age. We explore a link between the formation of these unusual clusters and an external perturbation of their host galaxy, illuminating a possible channel by which some clusters are born with large sizes
Fitting the integrated Spectral Energy Distributions of Galaxies
Fitting the spectral energy distributions (SEDs) of galaxies is an almost
universally used technique that has matured significantly in the last decade.
Model predictions and fitting procedures have improved significantly over this
time, attempting to keep up with the vastly increased volume and quality of
available data. We review here the field of SED fitting, describing the
modelling of ultraviolet to infrared galaxy SEDs, the creation of
multiwavelength data sets, and the methods used to fit model SEDs to observed
galaxy data sets. We touch upon the achievements and challenges in the major
ingredients of SED fitting, with a special emphasis on describing the interplay
between the quality of the available data, the quality of the available models,
and the best fitting technique to use in order to obtain a realistic
measurement as well as realistic uncertainties. We conclude that SED fitting
can be used effectively to derive a range of physical properties of galaxies,
such as redshift, stellar masses, star formation rates, dust masses, and
metallicities, with care taken not to over-interpret the available data. Yet
there still exist many issues such as estimating the age of the oldest stars in
a galaxy, finer details ofdust properties and dust-star geometry, and the
influences of poorly understood, luminous stellar types and phases. The
challenge for the coming years will be to improve both the models and the
observational data sets to resolve these uncertainties. The present review will
be made available on an interactive, moderated web page (sedfitting.org), where
the community can access and change the text. The intention is to expand the
text and keep it up to date over the coming years.Comment: 54 pages, 26 figures, Accepted for publication in Astrophysics &
Space Scienc
Designing a broad-spectrum integrative approach for cancer prevention and treatment
Targeted therapies and the consequent adoption of "personalized" oncology have achieved notablesuccesses in some cancers; however, significant problems remain with this approach. Many targetedtherapies are highly toxic, costs are extremely high, and most patients experience relapse after a fewdisease-free months. Relapses arise from genetic heterogeneity in tumors, which harbor therapy-resistantimmortalized cells that have adopted alternate and compensatory pathways (i.e., pathways that are notreliant upon the same mechanisms as those which have been targeted). To address these limitations, aninternational task force of 180 scientists was assembled to explore the concept of a low-toxicity "broad-spectrum" therapeutic approach that could simultaneously target many key pathways and mechanisms. Using cancer hallmark phenotypes and the tumor microenvironment to account for the various aspectsof relevant cancer biology, interdisciplinary teams reviewed each hallmark area and nominated a widerange of high-priority targets (74 in total) that could be modified to improve patient outcomes. For thesetargets, corresponding low-toxicity therapeutic approaches were then suggested, many of which werephytochemicals. Proposed actions on each target and all of the approaches were further reviewed forknown effects on other hallmark areas and the tumor microenvironment. Potential contrary or procar-cinogenic effects were found for 3.9% of the relationships between targets and hallmarks, and mixedevidence of complementary and contrary relationships was found for 7.1%. Approximately 67% of therelationships revealed potentially complementary effects, and the remainder had no known relationship. Among the approaches, 1.1% had contrary, 2.8% had mixed and 62.1% had complementary relationships. These results suggest that a broad-spectrum approach should be feasible from a safety standpoint. Thisnovel approach has potential to be relatively inexpensive, it should help us address stages and types ofcancer that lack conventional treatment, and it may reduce relapse risks. A proposed agenda for futureresearch is offered
Curious bivalves: Systematic utility and unusual properties of anomalodesmatan mitochondrial genomes
publisher: Elsevier articletitle: Curious bivalves: Systematic utility and unusual properties of anomalodesmatan mitochondrial genomes journaltitle: Molecular Phylogenetics and Evolution articlelink: http://dx.doi.org/10.1016/j.ympev.2017.03.004 content_type: article copyright: Crown Copyright © 2017 Published by Elsevier Inc. All rights reserved.The file attached is the final draft version of the article