349 research outputs found
On supersymmetric contributions to the CP asymmetry of the B -> phi K_S
We analyse the CP asymmetry of the B -> phi K_S process in general
supersymmetric models. In the framework of the mass insertion approximation, we
derive model independent limits for the mixing CP asymmetry. We show that
chromomagnetic type of operator may play an important role in accounting for
the deviation of the mixing CP asymmetry between B -> phi K_S and B -> J/psi
K_S processes observed by Belle and BaBar experiments. A possible correlation
between the direct and mixing CP asymmetry is also discussed. Finally, we apply
our result in minimal supergravity model and supersymmetric models with
non-universal soft terms.Comment: 19 pages, 3 figure
Sensory traits and consumer’s perceived quality of traditional and modern fresh market tomato varieties: A study in three European countries
Consumer dissatisfaction with the flavor quality of many modern fresh market tomato varieties has fostered breeders’ interest in sensory quality improvement, and the demand for traditional varieties, which are generally associated with better flavor. To achieve further knowledge on the factors influencing the sensory quality and consumers’ preferences and perception, European traditional and modern fresh market tomato varieties were grown and evaluated in France, Italy, and Spain. Different growing conditions were tested in France (soilless vs. soil) and in Spain (open field vs. greenhouse), while in Italy fruits were evaluated at two ripening stages. Fruit quality was assessed by integrating physicochemical analyses, sensory profiles, and consumer tests. In all three countries, overall modern varieties were perceived as having more intense “tomato flavor” and “overall flavor” than traditional ones. In France and Spain, consumers’ preferences were more oriented towards modern varieties than traditional ones. Significant growing condition effects were found on sensory and physicochemical traits, while the effect on consumers’ overall liking was not significant, largely depending on the genotype. A fair agreement between product configurations from descriptive analysis by trained assessors and Check-All-That-Apply (CATA) questions by consumers was observed. Penalty-lift analysis based on CATA allowed identifying positive and negative drivers of liking.Postprint (published version
Neutrino mixing and large CP violation in B physics
We show that in see-saw models of neutrino mass a la SUSY SO(10), the
observed large mixing in atmospheric neutrinos naturally leads to large b-s
transitions. If the associated new CP phase turns out to be large, this SUSY
contributions can drastically affect the CP violation in some of the B decay
channels yielding the beta and gamma angles of the unitarity triangle. They can
even produce sizeable CP asymmetries in some decay modes which are not CP
violating in the standard model context. Hence the observed large neutrino
mixing makes observations of low energy SUSY effect in some CP violating decay
channels potentially promising in spite of the agreement between the Standard
Model and data in K and B physics so far.Comment: References adde
The Minimal Supersymmetric Standard Model: Group Summary Report
CONTENTS: 1. Synopsis, 2. The MSSM Spectrum, 3. The Physical Parameters, 4.
Higgs Boson Production and Decays, 5. SUSY Particle Production and Decays, 6.
Experimental Bounds on SUSY Particle Masses, 7. References.Comment: 121 pages, latex + epsfig, graphicx, axodraw, Report of the MSSM
working group for the Workshop "GDR-Supersym\'etrie",France. Rep. PM/98-4
Comparative Study of CP Asymmetries in Supersymmetric Models
We systematically analyze the supersymmetric contributions to the mixing CP
asymmetries and branching ratios of B -> Phi K(S) and B -> eta(prime) K(S)
processes. We consider both gluino and chargino exchanges in a model
independent way by using the mass insertion approximation method. While we
adopt the QCD factorization approach for evaluating the corresponding hadronic
matrix elements, a critical comparison with predictions in naive factorization
one is also provided. We find that pure chargino contributions cannot
accommodate the current experimental results on CP asymmetries, mainly due to b
-> s gamma constraints. We show that charged Higgs contributions can relax
these constraints making chargino responsible for large asymmetries. On the
other hand, gluino exchanges can easily saturate both the constraints on B ->
Phi K(S) and B -> eta(prime) K(S) CP asymmetries. Moreover, we also find that
the simultaneous contributions from gluino and chargino exchanges could easily
account for the present experimental results on the mentioned asymmetries.
Remarkably, large experimentally allowed enhancements of B -> eta(prime) K(S)
branching ratio can easily be achieved by the contribution of two mass
insertions in gluino exchanges. Finally, we analyze the correlations between
the CP asymmetries of these processes and the direct CP asymmetry in b -> s
gamma decay. When all experimental constraints are satisfied, supersymmetry
favors large and positive values of b -> s gamma asymmetry.Comment: New figures and references added, version to appear on Nucl. Phys. B,
57 pages, LaTeX, 21 eps figure
A Quintessentially Geometric Model
We consider string inspired cosmology on a solitary -brane moving in the
background of a ring of branes located on a circle of radius . The motion of
the -brane transverse to the plane of the ring gives rise to a radion field
which can be mapped to a massive non-BPS Born-Infeld type field with a cosh
potential. For certain bounds of the brane tension we find an inflationary
phase is possible, with the string scale relatively close to the Planck scale.
The relevant perturbations and spectral indices are all well within the
expected observational bounds. The evolution of the universe eventually comes
to be dominated by dark energy, which we show is a late time attractor of the
model. However we also find that the equation of state is time dependent, and
will lead to late time Quintessence.Comment: 11 pages, 3 figures. References and comments adde
Coupled dark energy: Towards a general description of the dynamics
In dark energy models of scalar-field coupled to a barotropic perfect fluid,
the existence of cosmological scaling solutions restricts the Lagrangian of the
field \vp to p=X g(Xe^{\lambda \vp}), where X=-g^{\mu\nu} \partial_\mu \vp
\partial_\nu \vp /2, is a constant and is an arbitrary function.
We derive general evolution equations in an autonomous form for this Lagrangian
and investigate the stability of fixed points for several different dark energy
models--(i) ordinary (phantom) field, (ii) dilatonic ghost condensate, and
(iii) (phantom) tachyon. We find the existence of scalar-field dominant fixed
points (\Omega_\vp=1) with an accelerated expansion in all models
irrespective of the presence of the coupling between dark energy and dark
matter. These fixed points are always classically stable for a phantom field,
implying that the universe is eventually dominated by the energy density of a
scalar field if phantom is responsible for dark energy. When the equation of
state w_\vp for the field \vp is larger than -1, we find that scaling
solutions are stable if the scalar-field dominant solution is unstable, and
vice versa. Therefore in this case the final attractor is either a scaling
solution with constant \Omega_\vp satisfying 0<\Omega_\vp<1 or a
scalar-field dominant solution with \Omega_\vp=1.Comment: 21 pages, 5 figures; minor clarifications added, typos corrected and
references updated; final version to appear in JCA
Determination of QCD condensates from tau-decay data
We have used the latest data from the ALEPH Collaboration to extract values
for QCD condensates up to dimension d=12 in the V-A channel and up to dimension
d=8 in the V, A and V+A channels. Performing 2- and 3-parameter fits, we obtain
new results for the correlations of condensates. The results are consistent
among themselves and agree with most of the previous results found in the
literature.Comment: 22 page
Analysis of gene mutations associated with isoniazid, rifampicin and ethambutol resistance among Mycobacterium tuberculosis isolates from Ethiopia
<p>Abstract</p> <p>Background</p> <p>The emergence of drug resistance is one of the most important threats to tuberculosis control programs. This study was aimed to analyze the frequency of gene mutations associated with resistance to isoniazid (INH), rifampicin (RMP) and ethambutol (EMB) among <it>Mycobacterium tuberculosis </it>isolates from Northwest Ethiopia, and to assess the performance of the GenoType<sup>® </sup>MTBDRplus and GenoType<sup>® </sup>MTBDRsl assays as compared to the BacT/ALERT 3D system.</p> <p>Methods</p> <p>Two hundred sixty <it>Mycobacterium tuberculosis </it>isolates from smear positive tuberculosis patients diagnosed between March 2009 and July 2009 were included in this study. Drug susceptibility tests were performed in the Institute of Medical Microbiology and Epidemiology of Infectious Diseases, University Hospital of Leipzig, Germany.</p> <p>Results</p> <p>Of 260 isolates, mutations conferring resistance to INH, RMP, or EMB were detected in 35, 15, and 8 isolates, respectively, while multidrug resistance (MDR) was present in 13 of the isolates. Of 35 INH resistant strains, 33 had mutations in the <it>katG </it>gene at Ser315Thr 1 and two strains had mutation in the <it>inhA </it>gene at C15T. Among 15 RMP resistant isolates, 11 had <it>rpoB </it>gene mutation at Ser531Leu, one at His526Asp, and three strains had mutations only at the wild type probes. Of 8 EMB resistant strains, two had mutations in the <it>embB </it>gene at Met306Ile, one at Met306Val, and five strains had mutations only at the wild type probes. The GenoType<sup>® </sup>MTBDRplus assay had a sensitivity of 92% and specificity of 99% for INH resistance, and 100% sensitivity and specificity to detect RMP resistance and MDR. The GenoType<sup>® </sup>MTBDRsl assay had a sensitivity of 42% and specificity of 100% for EMB resistance.</p> <p>Conclusion</p> <p>The dominance of single gene mutations associated with the resistance to INH and RMP was observed in the codon 315 of the <it>katG </it>gene and codon 531 of the <it>rpoB </it>gene, respectively. The GenoType<sup>® </sup>MTBDRplus assay is a sensitive and specific tool for diagnosis of resistance to INH, RMP and MDR. However, the GenoType<sup>® </sup>MTBDRsl assay shows limitations in detecting resistance to EMB.</p
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