12,607 research outputs found
Impact of sterile neutrinos on nuclear-assisted cLFV processes
We discuss charged lepton flavour violating processes occurring in the
presence of muonic atoms, such as muon-electron conversion in nuclei
, the (Coulomb enhanced) decay of muonic atoms
into a pair of electrons BR(, N), as well as Muonium
conversion and decay, and .
Any experimental signal of these observables calls for scenarios of physics
beyond the Standard Model. In this work, we consider minimal extensions of the
Standard Model via the addition of sterile fermions, providing the
corresponding complete analytical expressions for all the considered
observables. We first consider an "ad hoc" extension with a single sterile
fermion state, and investigate its impact on the above observables. Two well
motivated mechanisms of neutrino mass generation are then considered: the
Inverse Seesaw embedded into the Standard Model, and the MSM. Our study
reveals that, depending on their mass range and on the active-sterile mixing
angles, sterile neutrinos can give significant contributions to the above
mentioned observables, some of them even lying within present and future
sensitivity of dedicated cLFV experiments. We complete the analysis by
confronting our results to other (direct and indirect) searches for sterile
fermions.Comment: 32 pages, 11 figures. v2: minor revision, matches published version
on JHE
Effect of steriles states on lepton magnetic moments and neutrinoless double beta decay
We address the impact of sterile fermion states on the anomalous magnetic
moment of charged leptons, as well as their contribution to neutrinoless double
beta decays. We illustrate our results in a minimal, effective extension of the
Standard Model by one sterile fermion state, and in a well-motivated framework
of neutrino mass generation, embedding the Inverse Seesaw into the Standard
Model. The simple "3+1" effective case succeeds in alleviating the tension
related to the muon anomalous magnetic moment, albeit only at the 3
level, and for light sterile states (corresponding to a }cosmologically
disfavoured regime). Interestingly, our analysis shows that a future observation does not necessarily imply an inverted hierarchy for the
active neutrinos in this simple extension. Although the Inverse Seesaw
realisation here addressed could indeed ease the tension in , bounds
from lepton universality in kaon decays mostly preclude this from happening.
However, these scenarios can also have a strong impact on the interpretation of
a future signal regarding the hierarchy of the active neutrino
mass spectrum.Comment: 25 pages, 19 figure
Fold-Saddle Bifurcation in Non-Smooth Vector Fields on the Plane
This paper presents results concerning bifurcations of 2D piecewise-smooth
dynamical systems governed by vector fields. Generic three parameter families
of a class of Non-Smooth Vector Fields are studied and its bifurcation diagrams
are exhibited. Our main result describes the unfolding of the so called
Fold-Saddle singularity
Future dynamics in f(R) theories
The gravity theories provide an alternative way to explain the current
cosmic acceleration without invoking dark energy matter component. However, the
freedom in the choice of the functional forms of gives rise to the
problem of how to constrain and break the degeneracy among these gravity
theories on theoretical and/or observational grounds. In this paper to proceed
further with the investigation on the potentialities, difficulties and
limitations of gravity, we examine the question as to whether the future
dynamics can be used to break the degeneracy between gravity theories by
investigating the future dynamics of spatially homogeneous and isotropic dust
flat models in two gravity theories, namely the well known gravity and another by A. Aviles et al., whose motivation comes
from the cosmographic approach to gravity. To this end we perform a
detailed numerical study of the future dynamic of these flat model in these
theories taking into account the recent constraints on the cosmological
parameters made by the Planck team. We show that besides being powerful for
discriminating between gravity theories, the future dynamics technique
can also be used to determine the fate of the Universe in the framework of
these gravity theories. Moreover, there emerges from our numerical
analysis that if we do not invoke a dark energy component with
equation-of-state parameter one still has dust flat FLRW solution
with a big rip, if gravity deviates from general relativity via . We also show that FLRW dust solutions with do not
necessarily lead to singularity.Comment: 12 pages, 8 figures. V2: Generality and implications of the results
are emphasized, connection with the recent literature improved, typos
corrected, references adde
The influence of stunting on obesity in adulthood: results from the EPIPorto cohort
Objective: To retrospectively investigate the association between short stature and increased sitting height ratio (SHR) â indicators of stunting â and obesity markers in adults.
Design: Cross-sectional evaluation of the EPIPorto cohort. Weight, height, sitting height and waist circumference were measured. Obesity was assessed for men and women through BMI and waist-to-height ratio (WHtR). Short stature (women, <152 cm; men, <164 cm) and high SHR (women, â„54·05 %; men, â„53·25 %) were taken as stunting measures. OR with 95 % CI were computed using logistic regression models.
Setting: Representative sample of adults from EPIPorto, an adult cohort study from Porto, Portugal.
Subjects: A sample of 1682 adults, aged 18â86 years, was analysed.
Results: Higher obesity prevalence was found among women (BMIâ„30·0 kg/m2: 25·5 v. 13·3 %, P<0·001) and a higher proportion of men presented abdominal obesity (WHtRâ„0·5: 80·1 v. 71·1 %, P<0·001). A positive association was found between short stature and obesity measures for women (multivariate-adjusted OR; 95 % CI: 1·75; 1·17, 2·62 for BMIâ„30·0 kg/m2; 1·89; 1·24, 2·87 for WHtRâ„0·5). Increased SHR was associated with higher likelihood of having BMIâ„30·0 kg/m2 in both sexes (multivariate-adjusted OR; 95 % CI: 2·10; 1·40, 3·16 for women; 1·92; 1·07, 3·43 for men) but not with WHtRâ„0·5.
Conclusions: Different growth markers are associated with obesity in adults. However, this association depends on the population and anthropometric measures used: short stature is associated with a higher risk of presenting excessive weight in women but not in men; SHR is more sensitive to detect this effect in both sexes
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