24,157 research outputs found

### 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

### Slepton mass splittings and cLFV in the SUSY seesaw in the light of recent experimental results

Following recent experimental developments, in this study we re-evaluate if
the interplay of high- and low-energy lepton flavour violating observables
remains a viable probe to test the high-scale type-I supersymmetric seesaw. Our
analysis shows that fully constrained supersymmetric scenarios no longer allow
to explore this interplay, since recent LHC data precludes the possibility of
having sizeable slepton mass differences for a slepton spectrum sufficiently
light to be produced, and in association to BR(mu -> e gamma) within
experimental reach. However, relaxing the strict universality of supersymmetric
soft-breaking terms, and fully exploring heavy neutrino dynamics, still allows
to have slepton mass splittings O(few %), for slepton masses accessible at the
LHC, with associated mu -> e gamma rates within future sensitivity. For these
scenarios, we illustrate how the correlation between high- and low-energy
lepton flavour violating observables allows to probe the high-scale
supersymmetric seesaw.Comment: 19 pages, 12 eps figures. References updated; matches version
accepted by JHE

### Universality of trap models in the ergodic time scale

Consider a sequence of possibly random graphs $G_N=(V_N, E_N)$, $N\ge 1$,
whose vertices's have i.i.d. weights $\{W^N_x : x\in V_N\}$ with a distribution
belonging to the basin of attraction of an $\alpha$-stable law, $0<\alpha<1$.
Let $X^N_t$, $t \ge 0$, be a continuous time simple random walk on $G_N$ which
waits a \emph{mean} $W^N_x$ exponential time at each vertex $x$. Under
considerably general hypotheses, we prove that in the ergodic time scale this
trap model converges in an appropriate topology to a $K$-process. We apply this
result to a class of graphs which includes the hypercube, the $d$-dimensional
torus, $d\ge 2$, random $d$-regular graphs and the largest component of
super-critical Erd\"os-R\'enyi random graphs

### 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
$\text{CR}(\mu -e, \text{ N})$, the (Coulomb enhanced) decay of muonic atoms
into a pair of electrons BR($\mu^- e^- \to e^- e^-$, N), as well as Muonium
conversion and decay, $\text{Mu}-\bar{\text{Mu}}$ and $\text{Mu}\to e^+ e^-$.
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 $\nu$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$\sigma$
level, and for light sterile states (corresponding to a }cosmologically
disfavoured regime). Interestingly, our analysis shows that a future $0 \nu 2
\beta$ 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 $(g-2)_\mu$, 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 $0 \nu 2 \beta$ signal regarding the hierarchy of the active neutrino
mass spectrum.Comment: 25 pages, 19 figure

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