12,741 research outputs found
Examining the cancellation mechanism of neutron EDM in a model with dilaton-dominated susy breaking
We examine the cancellation mechanism between the different contributions to
the electric dipole moment of the neutron in a model with dilaton-dominated
SUSY breaking. We find these accidental cancellations occur at few points in
parameter space. For a wide region of this space we must constrain the phase of
to be of order and have the phases of and strongly
correlated in order to have small neutron EDM. Moreover, we consider the
indirect CP violation parameter in this region where the electric
dipole moment is less than the experimental limit and find that we can generate
of order
Ice Accretion and Performance Degradation Calculations with LEWICE/NS
The LEWICE ice accretion computer code has been extended to include the solution of the two-dimensional Navier-Stokes equations. The code is modular and contains separate stand-alone program elements that create a grid, calculate the flow field parameters, calculate the droplet trajectory paths, determine the amount of ice growth, calculate aeroperformance changes, and plot results. The new elements of the code are described. Calculated results are compared to experiment for several cases, including both ice shape and drag rise
Supersymmetric contributions to B -> D K and the determination of angle \gamma
We analyze supersymmetric contributions to B^- -> D^0 K^- and B^- ->\bar{D}^0
K^- processes. We investigate the possibility that supersymmetric CP violating
phases can affect our determination for the angle \gamma in the unitary
triangle of Cabibbo-Kobayashi-Maskaw mixing matrix. We calculate the gluino and
chargino contributions to b--> u(\bar{c}s) and b-->c(\bar{u}s) transitions in a
model independent way by using the mass insertion approximation method. We also
revise the D^0 - \bar{D}^0 mixing constraints on the mass insertions between
the first and second generations of the up sector. We emphasize that in case of
negligible D^0 -\bar{D}^0 mixing, one should consider simultaneous
contributions from more than one mass insertion in order to be able to obtain
the CP asymmetries of these processes within their 1\sigma experimental range.
However, with a large D^0-\bar{D}^0 mixing, one finds a significant deviation
between the two asymmetries and it becomes natural to have them of order the
central values of their experimental measurements.Comment: 20 page
Magnetic Response of Magnetospirillum Gryphiswaldense
In this study we modelled and measured the U-turn trajectories of individual
magnetotactic bacteria under the application of rotating magnetic fields,
ranging in ampitude from 1 to 12 mT. The model is based on the balance between
rotational drag and magnetic torque. For accurate verification of this model,
bacteria were observed inside 5 m tall microfluidic channels, so that they
remained in focus during the entire trajectory. From the analysis of hundreds
of trajectories and accurate measurements of bacteria and magnetosome chain
dimensions, we confirmed that the model is correct within measurement error.
The resulting average rate of rotation of Magnetospirillum Gryphiswaldense is
0.74 +- 0.03 rad/mTs.Comment: 17 pages, 12 figure
Kinetics, Activation Parameters, and Mechanism of the Acid Hydrolysis of tert-Butyl Acetate in Aqueous DMSO
The rate of the acid-catalysed hydrolysis of tert-butyl acetate
was found to decrease pronouncly in the presence of increasing
amounts of DMSO. The observed activation energy decreased progressively
with increasing DMSO content of the medium and the
change was attributed to a gradual interconversion of the two
concurrent and competing reaction mechanisms AALl and AAc2.
The overall reaction rate was analysed theoretically as two individual
rate constants corresponding to the respective mechanisms.
The percentage contribution of each mechanism was then estimated
and found to be concordant with the values determined experimentally
by others using 180 tracer technique. The proportion of
the AALl mechanism was found to increase both with increasing
temperature and decreasing DMSO content. The relative abundance
of the transition state belonging to each of the involved mechanisms
was discussed in the light of the solvating power of the binary DMSO-H20 solvent system. The effect of the molar concentration of water as well as the dielectric constant of the medium on the reaction kinetics was studied. The thermodynamic parameters of activation showed strong dependence on solvent composition and their values were determined by the relative contributions of the two mechanistic routes of the reaction
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Extracting Arabic composite names using genitive principles of Arabic grammar
Named Entity Recognition (NER) is a basic prerequisite of using Natural Language Processing (NLP) for information retrieval. Arabic NER is especially challenging as the language is morphologically rich and has short vowels with no capitalisation convention. This article presents a novel rule-based approach that uses linguistic grammar-based techniques to extract Arabic composite names from Arabic text. Our approach uniquely exploits the genitive Arabic grammar rules; in particular, the rules regarding the identification of definite nouns (معرفة) and indefinite nouns (نكرة) to support the process of extracting composite names. Based on domain knowledge and Arabic Genitive Rules (AGR), the developed approach formalises a set of syntactical rules and linguistic patterns that initially use genitive patterns to classify definiteness within phrases and then extracts proper composite names from the unstructured text. The developed novel approach does not place any constraints on the length of the Arabic composite name and our initial experimentation demonstrated high recall and precision results when the NER algorithm was applied to a financial domain corpus
Sterile neutrino dark matter in extension of the standard model and galactic 511 keV line
Sterile right-handed neutrinos can be naturally embedded in a low scale
gauged extension of the standard model. We show that, within a low
reheating scenario, such a neutrino is an interesting candidate for dark
matter. We emphasize that if the neutrino mass is of order of MeV, then it
accounts for the measured dark matter relic density and also accommodates the
observed flux of 511 keV photons from the galactic bulge.Comment: 10 pages, 1 figure, references added, final version appeared in JCA
Muon Anomalous Magnetic Moment and mu -> e gamma in B-L Model with Inverse Seesaw
We study the anomalous magnetic moment of the muon, a_\mu, and lepton flavor
violating decay \mu -> e \gamma in TeV scale B-L extension of the Standard
Model (SM) with inverse seesaw mechanism. We show that the B-L contributions to
a_\mu are severely constrained, therefore the SM contribution remains intact.
We also emphasize that the current experimental limit of BR(\mu -> e \gamma)
can be satisfied for a wide range of parameter space and it can be within the
reach of MEG experiment.Comment: 10 pages, 4 Figure
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